Pond Boss Forums AERATION Systems questions Ideal aeration schedule

I have an approximately 1/3 acre pond with a dual diffuser aerator running from a gast 0523. I also have a windmill powered aerator but it is very sporadic given a large tree line to the west of my pond and I’m probably lucky to get 1 CFM ona good windy day. I’d like to run the aerator part time to save electricity costs and I believe my air pump is sufficiently large enough to do so on a pond my size. My question is, if I were to run it 12 hours a day would it be better to run 12 hours consecutively or break it up into intervals. Currently I’m running about 3 hours at 4 evenly spaced intervals. Also is there a better time of day to run. I’ve heard oxygen levels are lowest at night. Would it be best to run at night and not during the day or vise versa or does it really just not matter. What impact would of have on the wear and tear of the pump. Are frequent shorter intervals better or worse than longer less frequent intervals? Thanks.

Very good question that I do not have the answer to but will be very interested in the answers you get.

Here is an old thread that also will not answer your question but may raise some more and might give you some insights you may not thought about.

Aeration turnover rate

I think there is still a lot to be understood about aeration.

I will say this. I went to a larger capacity pump with considerable more air output than I had been using. I THINK the increased air flow and turnover rate has improved my water quality. I have had problems in past with cyanobacteria (bluegreen algae) during the dog days of summer when pond water levels are low in the past. My water level is very low this year and with the higher capacity pump (even though I do not run it all the time like I did my previous setup) I have had almost no sign of problems.

I have some different ideas about the best time to run the pump (when running less than 24-7) as you will find out if you read the linked thread. But I have no idea that my idea is correct and since I am in a minority view it is likely wrong. As you can tell from that thread, there are still lots of questions that have ideas but few hard "facts" about aeration. There are soooooo many variables and differences in ponds it is hard to give a "one size fits all" recommendation. Yet there is enough experience that at least we do have some general rules of thumb.

Hoping you get a good answer.

I will say one thing about multiple starts and stops of the pump. It takes more electricity each start cycle of the motor. I don't know if it is enough more to make any significant difference in your electric bill, but a motor does draw significantly more amps on startup than in run mode. 4 times a day???? Maybe no big deal. But if you were starting it 20 times a day I think you would see increased electric bill. My opinion - I'm no electrician.

I am really just a beginner with aeration, but love to "talk" it up, so take my ramblings with a tablespoon of sugar.



snrub's hit it right on the head with the above quote.


In very basic terms...

The fewer times you start the electric motor the cheaper it is to operate given that the overall runtime is the same. Starting and stopping a motor repeatedly during an hour requires a more energy than just letting it run all a hour long. This cost savings would be minimal with these little motors over the course of 12 hours and only 4 start/stop cycles. So, this savings could easily be ignored or next to impossible to realize on an electricity bill. (Backing up snrub again)

The fewer times you start the electric motor the less wear it will have given normal operating conditions (e.g. no excessive heat or moisture in the pumps environment).

With that said, let's consider running the aerator 12 straight hours, but realizing that the benefits are minimal compared to cycling on/off periodically throughout the day. Although, I am having a hard time arguing one way or the other, it could be chalked up to personal preference unless water temps come into play...see below.

With your pond in a northern climate, but not too far north, it may not make a lot of difference what time of day you run the system during the summer unless you have cold water fish like trout. At any rate, determine what water temps your fish like and run the aerators to accommodate that temp. e.g. if you think your water temp is too hot, then run the system only at night OR if its too chilly - run it during the day to utilize the day's heat to warm the waters. I expect my system to flip from nights to days as fall approaches and eventually be shut down during the winter.

I am finding that my aeration system (Gast 0523 and 3 vertex single diffusers) running from 9pm to 9am stabilizes the temps in general, but is not a real game changer unless the pond finds itself on the verge of a fish-kill. So far so good, I think of my aeration system as insurance and as a capacity increaser. It does cycle the muddiness of the pond though. Muddier in the morning and less so in the evening. I think cycling the system 4 times a day would keep the clarity, or lack thereof, more consistently muddier. I'm not say that is good or bad...just saying.

Here is a recent thread that I ramble even more if you care see some temp data from before and after aeration start-up along with some more of my theories...

http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=495076#Post495076

I battled the water temp issue for the first time this Summer. I recorded higher water temps than I have ever seen so I switched to 100% nighttime aeration.

IMHO, all else being equal and removing water temps from the equation. If DO levels are known to be lowest right before sunrise then aeration at night logically seems to be the most needed to aerate.

Someone please correct me if I am wrong!

I have thought the same, but do not have any real evidence to back it up.

I think that oxygen will dissolve into the water more so during the day time mainly because I think that winds are stronger during the day compared to night. This would yield a better air to water interface. Are these safe statements? If so, aeration would be more efficient during the daytime, but would likely more productive at night due to less wind action and the absence of photosynthesis.

I'm on board WB!

QA - I think it is the not only the lack of photosynthesis at night, but the O2 CONSUMPTION by plankton, plants, etc at night that really moves the DO needle. I imagine the rate of consumption would increase as a ponds productivity increased.

I tend to look at your theory about daytime winds in a slightly different way. The stronger winds during the day would provide their own contribution to, or form of, aeration. So you have SOME aeration "input" during the day. To me, that would be more of a reason aeration COULD be more beneficial/needed at night.

Again, I think it has been proven that if you measure your DO at 6am it will be lower than at 2pm. That just leads me to believe the most effective/most needed time to aerate is at night.

Honestly, I prefer to see the lake in it's natural state anyway rather than aeration plumes everywhere. So TO ME aeration at night is aesthetically preferable as well.


I hope that doesn't sound argumentative at all because I am definitely not arguing AND I have definitely made plenty of incorrect assumptions!

My thinking...which doesn't say much ...is there should be an optimal number for fish survival / or plant...I think one would target this number then monitor DO levels at different times of days then different times of year. That would tell you on average when you should run it and not. Is it possible to have a pond with too much DO and will at some point the aeration be useless for fish?

I run ours at night to cool the pond down and cut back on alga. I have been told to check the shore line in the morning for small bubbles on the surface of rocks. The bubbles indicate good O2 saturation.

I think your assumptions are dead on Mr Buffet. If you look back at all the reported summer fish kills, the vast majority of them occur in the morning hours when all available DO has been consumed. While wind does provide a mixing of daytime oxygen, that oxygen stays primarily closer to the surface. With added heat, the fish want to be deeper, but have to suffer lower O2 levels until they're forced to go shallow, which in turn adds another stressor, causing them to consume even more O2.

In small ponds like mine, wind aeration is virtually nill, so aeration not only helps, but is necessary. Running at night for me is the only way to go short of 24/7, and my thoughts are 24/7 may help maintain higher levels of DO, but you're also threatening to super heat everything...I'm deep, deep south.

I start pumping air at 8p and run 12 hours. When it shuts off, the first rays of sun are hitting the pond. By 10:30 it's full sun, until 3:30, when shade starts creeping back in. As the shade increases, photosynthesis decreases, so before it drops too low, I'm already supplementing air.

Nice input...I, now, have a reason to go to the pond before work. Bubble hunting!

QA - haha, while you are there you might as well start measuring morning temps and combine with your other data!!

Oh No! Actually, You're right, but I don't know if I have it in me. Bubble hunting = a few minutes...temp readings about 20. How about I just do weekends? That can work! And, I think secchi readings would be most interesting.

One of these days we are going to be some well educated folks!!!

One thing to keep in mind when it comes to aeration. It is easy to be mislead to think that when we switch the air pump on we are starting aeration and increasing DO. Keep in mind that the bubbles themselves are only infusing a minute amount of DO. When we flip the switch on the pump motor what we are really doing is moving water.

Specifically we are moving lower water in the pond to the surface. It is this surface interaction that increases the DO for the most part as far as the water movement is concerned and if it is daylight hours algae is causing a lot more DO in the water than the air/water interface at the surface.

So when we flip that switch on and the motor hums are we increasing DO? Yes in the aggregate for the entire BOW we would. But would we be increasing it where the fish need it at that particular moment? I think it depends.

Disclaimer: I'm no expert and have lots more questions than answers. These are my thoughts not to be confused with actual good information. Keep that in mind as you read.

So when you flip that switch and start pumping water from depths to the surface the water that hits the surface infuses DO. But is that water on the bottom of the pond already sufficient with DO for the fish? Or is it deficient in DO? I think it depends on a lot of things. If adequate aeration was done at some earlier point where the lower water is still in good DO shape maybe that lower water is not too deficient in DO. But what if it is almost devoid of DO?

There are still questions in my mind if pumping water only during night hours is a good thing. I would think that pumping during some daylight hours where algae has a chance to mix with the water coming from the bottom and give that a quicker DO boost would be desirable. I would think that circulating some of that super saturated DO daylight surface water down into the lower regions of the pond to infuse it with DO to provide a DO "sink" would be desirable.

Rantings of someone that has a lot more questions than answers. For what it is worth I am running my pump from about 3am to noon and 5 to 8 pm. Trying to avoid the hottest part of the day yet circulate water while DO infusion by algae is still high.

Edit: It is my contention that from a DO standpoint pumping nutrient rich lower water up to the surface and mixing it with algae laden water would infuse much more DO in the BOW than pumping at night when the algae is dormant. But that does not address the problem of overheating the water.

Thats exactly the situation I've found myself in snrub. After checking temps yesterday evening, I found only 3 degrees difference between water 20" deep and on the bottom. Even with elevated diffusers, the bottom temp is 88 degrees....way too warm. I've cut my run cycle in half as of last night, running only 6 hours, since I'm apparently over circulating the pond.

Hopefully, this shorter run will still give me a good mix, but allow for some natural cooling at depth. Time will tell.

Edit: when I adjusted my run time yesterday, I reduced hours from both ends of the cycle. After some thought, I'll make another adjustment today to have the pump running from 2am till 8am. Hopefully this will allow for more cooling prior to start-up and add oxygen during that period when its most needed.

According to some loose calculations that I have done for my 1/4 acre pond (estimated to have 423,000 gallons of water) using Vertex's lift rate chart...A single vertex diffuser at 8 foot deep will turn my 1/4 acre pond over 4.3 times a day running 24/7.

For a 1/10th acre pond, the same calculations would allow for runtimes to be as little as an hour to achieve a once a day turn over. I am going to stick my neck out here and say that with the heat you are seeing from top to bottom and the size of your pond (0.1 acre) that raising the diffuser and reducing runtime will be required. I look forward to your results and, by no means, make any decisions based on my ramblings.

I wonder where kramedt is? He'll be surprised at the storm he has created, however, the timing was perfect!

I'm not using Vertex, but I definitely need to contact the folks I bought the system from and find out if they can tell me what the turnover rate for their diffusers are. These are tubular membrane and didn't come with any data on the diffusers... Just the pump...which is Greek to me!!!

It may boil down to trial and error to find the right run time, and it's possible that I may end up raising the diffusers even higher to allow a little bottom stratification if I can't get the temp right.

I may have to look into a DO meter to get a better handle on what's going on so I can try to dial in to the right combination of temp and DO.

I like that the system is circulating the entire pond, even with the diffusers elevated 22". If I can get by with 4-6 hours, so much the better!!

One more thought to add to all this. Someone would somehow need to figure in the fact that colder water has the ability to hold more oxygen. There would be some additional benefit/offset to running at night with much cooler temps. Would the lower temps and increased O2 capacity at night offset the plankton input during higher temps? If so, how much?

Last year I ran the 1HP pump A LOT during the day only. This year I am running the 1/2HP pump only at night for similar duration as last year. I wish the setups weren't so different and we would have some real data to compare. I will say that if my September 2018 (1/2HP) numbers somehow compare favorably to my September 2017 (1HP) numbers things will get very interesting.

I find myself returning to the same thought process. So I will say it one last time.

In the spirit of K.I.S.S.

If DO levels drop at night and are lowest at sunrise, isn't aeration mostly needed/effective at night??

I would run aeration 24/7 if rising temps were not a concern. Since rising temps for our small ponds IS a concern, I'm on board. Two birds with one stone. Run at night to maximize aeration affects and minimize temp rises.

DO is most needed at the end of night early in the morning near sunrise. But replace the word aeration in your statement abover with "water movement from lower to upper regions of the pond" since that is actually what your aeration equipment is doing. Yes, your needs for more DO is in the pre-dawn hours. But is moving lower water upward (which is actually what your doing) accomplishing that goal?

I do not know. I'm asking. It just seems to me we may be equating the pump running as adding DO (it does at the surface but does it where the fish are residing?) but ignoring what the pump is actually doing which is moving lower water (could be lower or higher in DO depending on a number of factors such as how much high DO water was moved to the lower region at an earlier time) to the surface.

I know more than I understand and I don't know enough. Sounds like something Yogi Berra would say.

I'm certainly new to all this but don't forget that if you are moving lower water up with aeration that the water that's moving up is replaced by water residing elsewhere in the pond. While it's not directly pulling water from the surface down it certainly would seem to imply that if one looks at all the diagrams that aeration companies put out on how aeration destroys the stratification layer.

When initially starting up the upwelling water would be colder than the surface water and would tend to sink back down faster but it will at the same time be mixing with the warmer surface water. However the average temperature should be lower than the unmixed surface water and so it should still sink - moving some of the mixed surface water down to the lower depths.

That process would probably continue until the BOW is at a more or less uniform temperature with little to no stratification. No clue where the water to replace the upwelling water comes from at that point but the fancy diagrams suggest the cycle just continues with surface water falling to the lower regions - which may be the case when the water cools in the evening. During the heat of the day it probably just continues to look like a blender.

Just my $0.02 but not based on any real science.

Snrub - At this point I am assuming most folks in these conversations understand that by saying aeration we mean moving the bottom water up, BUT you know what they say about assumptions.

I am not sure I understand the part of your question that I put in bold. We know that moving bottom water to the surface increases our DO, aren't we just trying to pick the best time to do it??

I learned that once water reaches the air/water interface water is extremely efficient at exchanging "gases" for O2. The exchange is almost instantaneous. So once that low/no DO water reaches the surface it becomes highly oxygenated. I am ASSUMING that water raised to the surface becomes more oxygenated than water that sits 1' or 1" below the surface somewhere else on the pond. Isn't that raising our DO no matter day or night?

I don't know enough either!! Where is Bill Cody!!??

Yes. That is what I said I believe.

But if I recall what Cody said, the air water interface affects a very small amount of water right at the surface.

If I recall what he said correctly, the majority of DO infusion comes from algae respiration during the daylight hours and produces O2 at all levels the algae see sunlight.

If that is true (and I remember correctly what he said) daylight hours are multiple times more effective at infusing DO into the BOW.

That is why I wonder if night only operation is not short changing the capability of the aeration system to add DO to the BOW. But I also understand the problem of over heating the entire BOW. So it would seem to me there are two different issues that are at odds with each other.

I contacted the company I bought my system from and, as I suspected, they weren't able to tell me what the turnover rate is for this setup.

Looks like I'm gonna have to do more trial and error and hope I don't error to big!!

I've reduced run times to 6 hours, coming on at midnight, but I may adjust again to come on even later, maintaining a 6 hour run. It's apparent the system is getting a full turnover with the little difference in temps I found running 12 hours. My goal is to reach an optimum bottom temp, with adequate O2. I think the DO will be there, but the temps need to come down. I'm thinking 88 degrees is borderline superheating.

Can someone tell me what that temp target should be? As small as my pond is, I may not be able to get that cool in the heat of the summer, but at least I'll have something to shoot for.

I think I see where you are going with this. Are you saying running aeration during the day the plankton can add O2 to the entire column of water being moved by the aeration? The way I understood it, as soon as the water reaches the air/water interface the exchange happens and the water absorbs all the O2 it can hold. I am probably wrong, but I don't think you are getting any EXTRA O2 from the plankton. The air/water interface only affects the small amount of water at the surface but with aeration we are constantly exposing thousands of gallons to the surface and every ounce of water in that column that reaches the surface will end up fully oxygenated whether day or night. Great discussion!

Of course water temps, etc are really going to drive a pondmeister's decision to aerate during the day or night. It is still fun to discuss, all else being equal, is day or night more efficient.

I may just be completely over thinking the issue too!

I got another email from the company I bought my system from. Apparently they've never been asked the question about lift rate on any of their systems, but they were able to give me some numbers.

These are their words, not mine...
From what they relayed to me, my system is designed to produce 1.1 cfm at 30 feet. I'm set up at 8 feet, so I should be realizing every bit of what the pump is capable of. That being said....

1.1 cfm x 60 minutes = 66 cfh x 7.48 (cf of water) = 514.8 gallons per hour.

If I calculated my total pond gallons correctly, I've got approximately 187,000 gallons (60L x 60W x 7 avg depth (just a guess on avg depth) x 7.48).

If I'm lifting 515 gph that means I need to run 363 (187,000 ÷ 515) hours to get a single turnover!!??

I think I'm missing something because that just doesn't seem right with what I'm seeing temperature wise. I've reduced to running 6 hours for now (midnight to 6am) due to not having any thermocline and only 3 degrees variance from 20" to 10.5' (91 & 88 respectively) after only 3 days of running 12 hour shifts.

What part of this calculation am I missing? My goal is to run only as long as I need to, to get 1 complete turnover of the pond.

Somebody, please, help a fella out here.

I don't know the exact math but trying to equate the volume of water being moved to the volume of air on a 1:1 basis is incorrect. It may be proportional but it is more dependent on the bubble size and not just the air volume. Otherwise you wouldn't need a diffuser and could just stick the end of the hose in the pond.

In my case I have tubular ring diffusers. I too asked the supplier about lift rates and, not surprisingly, they didn't have an answer. Just a generic reply that it all depends on the exact situation. Based on the size of the upwelling when running they have to be moving at least several hundred GPM, if not more.

When I measured the temperature differences yesterday morning after running from 3am-7am they were within 1 degree at virtually all depths. With the system off at mid-day there was a 7 degree difference from the surface to 4 feet down.

This is all anecdotal of course (other than the temperatures) as I've no way to actually measure the volume of water being moved. I guess one could use a large diameter column and build a makeshift airlift and capture the water but that sounds like too much work.

Mike, I perused your calcs and they look good, but I think the "1.1 cfm at 30ft" must be the amount of air the pump will put out at a depth of 30 feet NOT the amount of water that it moves. It's just too small.

I know you know what you are asking for (lift rate), but I don't think your aeration company knows what your asking for.

OR the system is designed for a very small yard pond, but surely that is not the case since they spec it a 30 foot of water depth.

Also, for point of reference, Vertex shows with their lift rate chart that the volume of water that gets moved actually increases as the diffuser gets deeper. This is given that the minimum recommended amount of air flow is provided and other brand diffusers should be no different.

Tom makes a good point about the air flow to water flow ratio! I can estimate my ratio for a single vertex diffuser at 7 feet deep by the following...

7 foot deep yields 3.5 psi PLUS a little backpressure (1.5psi) from the length/size of tubing that I use PLUS 1 psi for the diffuser itself. In total = 6psi. This jives with the pressure gage on my system pretty close. From the chart below using the top right graph...



...we can see that my pump puts out about 4 CFM of air. That's the first part of the ratio. Using the Vertex chart above, my single diffuser would move about 1200 GPM at 7 feet deep. Converting to CFM...1200 GPM/7.48 G/CF = 160 CFM of water.


Ratio of Pump Air to Water Movement (in CFM at 7 feet deep) is 4:160 OR 1 to 40.

I'm not sure what this mumbo jumbo is good for unless you can somehow equate your diffuser to the vertex one and know the air flow at the depth of your diffuser.

One of the reasons I bought Vertex was the fact that they had some mumbo jumbo numbers to fiddle with cause that's what I do.

Do you have a pump chart? I am almost 100% sure it puts out more air at shallower depths and if we could somehow compare a bubble boil between yours and a vertex one we could guestimate the water movement, albeit very crude, but better than what the company has given you so far.

If the real goal is having decent DO levels at all depths then just measuring the temperatures at various depths may be a valid way to determine if complete turnover has occurred based on this post from Bill Cody a few months ago.

It's a long read but worth it if you haven't already seen it.

http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=30739#Post30739

Great old thread. Thanks for the link.

Cody: "The "when" to run it is ONLY a debatable issue if you can do a pond turnover in less than 12-18 hours."

Maybe Bill would grace us with an update to this 2005 thread comments.

Hey Noel,
Yes, the pump did come with a chart. I'll have to compare it to what you posted above to see how it corilates, when I get home this afternoon.

As far as boil, the immediate area of the boil looks to be about 3 foot in diameter, maybe 4, pushing water up at least an inch at the surface. When I looked at it this morning, the clean water line (no algae or film) was at least 40 feet in diameter. Thats encompassing all but the very outer 10 foot of the pond's banks.

At some point, I guess I'll need to plumb in an air gage so I can measure pressure at the pump. Right now it's straight lined in. Takes about 5 seconds max for the boil to erupt when the pump comes on.

My major concern, feeling like I've achieved complete turnover due to such a tight variance in temps, is trying not to over circulate so I'm not over heating the bottom of the pond. If I can get by with 6 hours, or even less to get the pond to saturate with O2, then in my thinking, that would be more beneficial from a temperature standpoint.

I'm going to get more temp readings today to see what the 6 hour cycle time has done. I may have to install a plate beneath the diffusers to try to reduce the amount of lift I'm pulling up from the bottom and see if that creates some cooler water at depth.

Good description regarding your boil, it painted the picture. It sounds very similar to mine. I'm not sure that I get 40 foot diameter clean water lines, but close. Keep in mind that I have 3 diffusers so the two shallow ones steal air from the main one. I would feel comfortable that using vertex's charts and/or your pump chart would yield close estimates wrt turnovers per day.

I've been looking for videos of the mixing effects and ran across this which may be enlightening. Not sure if it applies 100% but it was surprising how fast things mixed.

https://youtu.be/FE9VbiVbZFM?t=60

It's not a direct comparison due to the difference in the aerator design but still interesting.

I'm now thinking of adding some pond blue to my deep aerator airline to see what happens.

Hey Tom,
I just read thru the post you attached earlier. What I take from that discussion is, if you don't have a DO meter, then temps ranging less than 5 degrees from top to bottom is a relatively good method of determining O2 saturation throughout the area of the diffuser.

That being said, with a variance of only 3 degrees from 20" to 10.5' and a visibility of approx 24", I think my assumption of having a full turnover are validated.

This raises other questions for those of us with deep South ponds....

1) How warm is too warm?

I've found some postings elsewhere that say that 88-90 water is very tolerable by BG,LMB and RES, and I know GSF seem to like it hot as they are always right against the banks. I'm figuring most other species of panfish are just as tolerant to these temps as well. But when does it become unhealthy for all of our finned residents?

2) From a pond health standpoint, knowing warmer water holds less oxygen, how does warmer water affect the anaerobic digestion of detritus and accumulated muck?

That YouTube video sure does give you a good perspective on how bubbles influence water flow. I wish they'd done it with a single, centrally positioned diffuser.

I agree, great old thread and would be very interesting to hear Bill's thoughts almost 15 years later!

Great find, Thanks Tom

Noel,

I'm trying to make sense of this chart that came with my pump. If I'm understanding it, at 1.0 CFM (there's only one solid line) the pump is creating 7.9 psig. Without an air pressure gage, I've no idea what the pump is generating. So going with depth of 8.5', that's 4.25 psi on the diffuser. 50 ft of 3/8 line may create 1 psi, leaving 1.75 psi in excess, so I think I'm pushing some pretty reasonable air.

Looking at your vertex info sheet on diffusers, I'm not sure if I should compare to the single or double diffuser info. Mine is a double diffuser, but being tubular, I'm sure there is some variance as compared to a disk. For the sake of argument, I'll go with the single diffuser data.

At 8 feet, if I'm actually getting 1250 gpm of lift, that's 75000 gph. With 187000 gallons in the pond, I'm moving every bit of the pond in just under 3 hours. Everything being pure speculation.

Temp readings at 6pm registered 2 degrees difference between 20" and 10.5' (90 & 88 respectively). We've had cloud cover and rain on and off most of the day, so that contributed to the 1 degree drop at 20".

At this point, my question is still...how warm is too warm for both the fish and the pond as a whole?

Fish seem to be happy and fed like pirahna today.

Mike, sometimes it takes me several breaths and maybe some sleep to understand pump charts. So without noodling your chart...I would say you are on the right track. And using the lesser of the Vertex diffuser lift numbers keeps you on the safe side anyhow. In fact, throw in a goobery safety factor in of 1/2 and you are still turning your pond in six hours time.

Share your chart if you can post a pic of it, that will help. I bet your pump is a diaphragm or some sort of positive placement pump, like piston.

For some reason, my fish have backed off from feeding a fair bit lately and my water temps just 6 days ago were 78 top to bottom (they fed well then), but the summer heat came back and I am still at 78 on the bottom, but 84 at 18" down. The fact that your fish are eating well says a lot to me.

I need to find a host to get some pics on here. I've got a couple of plants I'd like some input on as well.

You are correct on the pump, its a Gast 1/8 hp diaphram, model DOA-P701-AA. Hopefully only running it 6 hours will give it a good long service life. The whole kit is marketed as EasyPro. I think it draws 4.2 amps, so a 6 hour run wont break the bank either!!

I've been pretty pleased with my fish, they're feeding well and growing. Looking forward to soaking some crickets soon and harvesting a few. Kinda torn about what size GSF to take out. They've been helping keep the fry and YOY in check. (And I'm kind of curious just how big I can get them). Seeing more and more 4-6" BG and a few over 7 now and lots of 3-5 inchers. GSF are as fat and sassy as ever and remarkably, still have a few nest tenders. Haven't seen much of my 3 LMB since I put the aeration in tho. Just a glimps of one every now and then.

I guess I need to quit being so anal about the temp and let the fish tell me how they're doing more. 88-91 doesn't seem to bother them much. All in all, the pond seems to be doing decent.

That is a neat video, thanks for posting it.

I will say that putting dye in a pond, even without aeration, it disperses amazingly quickly. I was surprised at how quickly it spread throughout the whole surface.

But I would suspect it only dispersed (without aeration) only near the surface or at least above the thermocline. That is what the vertical pumping of water of the aeration system does. Mixes the different density cold lower water with the upper lighter warmer water.

If you go swimming and approach the diffuser, on mine about 10-15 feet away you can feel the cold water difference as the diffused plume of bubbles brings up the cold water and it disperses across the surface just like the video shows.

I think wind (or lack thereof) also plays a big role. With no wind that cold water that surfaces could have the inclination to drop again as it moves away from the diffuser plume. But with any wind at all the surface current will quickly move it away from the plume. It is surprising how many and much current there is in a pond created by wind and also just by the sun warming. Dye would work well to show the currents. Even mud will do it. Mix up some clay in water and dump it in some area and watch natural currents disperse it.

This thread reads like you guys have things pretty well figured and calculated closely to what is really occurring with Mike's system.

The only thing I would add or modify to my prior post of several years ago is the amount of DO that is needed on the bottom sediment areas. I currently think 5ppm is more than adequate for good invertebrate and bacterial decomposition of bottom sediments. IMO Good decomposition of deep water sediments can occur in 1-2ppm dissolved oxygen at the sediment water interface in the pond's deepest water "belly". However if you want good fish diversity of all species living in the deep water area of the pond then 4-5ppm dissolved oxygen is needed.

Unless there are some specific questions I won't need to add anything else.

Thanks for chiming in Mr. Cody. Your insight of DO saturation at depth will be beneficial for any future considerations. If you could offer some of your experience regarding water temps, I for one, would be very grateful.

As stated earlier, I think I'm ok for now, but my concern is that I'm pushing the boundaries of what may be safe, temperature wise.

Short of infusing cooler well water into the pond, there's not much else I can do to reduce the heat if I'm going to aerate the pond. Being a small pond, some things happen much faster than on large BOWs, temps being the most obvious.

I guess my question would be how much can I reduce temps at once and not be detrimental?

I've got a small floating fountain which runs 24/7 so that keeps the surface water moving a bit on my small pond. I guess it also, at least in theory, helps reduce the water temperature through evaporative cooling. However I'm not sure if it might actually add to the heat load on extremely hot days.

That's my concern Tom. Eventually, the air temps may overpower the circulation and everything just keeps getting hotter over time and the whole pond overheats. At one time this summer my surface temps reached 99 degrees before I put in the system.

Running only 6 hrs at night, I've reduced the temp variance from top to bottom to only 3 degrees in just a week. That's why I'm thinking infusion of cooler well water may be my only option. I can maintain a full pond that way as well. Even with 10.5 feet of depth I'm 88 degrees on the bottom, 91 degrees 20" down.

You might try adding some additional shade, even if temporary. One idea would be to just throw in several 1/2" 4x8 sheets of the pink foam insulation to provide floating shade from the direct sun. They're not terribly expensive.

This summer is my 3rd year of running Kasco diffusers. The bottom of my 3+ acre pond has two different pool depths separated by a roadbed, ridge or whatever one wants to call it. Pool depths very during the summer but basically it is 10' and about an acre of it and 12' about a half acre depths for the most part with the remaining acreage running around 5' depths. My water temps ran 87 last year top to bottom and my Do ran between 5 and 6ppm. This year after watching facebook live with Mr Lusk I changed 4 diffusers and placed them off bottom or about 7 to 9' water depths. Now after doing this the water temps below those depths is about 8 to 10 degrees cooler. I have not been able to ck the DO because my meter probe is broken and waiting on another one to show up. But I will say, I have seen some improvement in fish activity over this summer and when running my fish finder I find fish from top to bottom in the pond. I think this setup is much better and I will keep it this way.

I was hoping that by elevating my diffusers they would create the same conditions you have Tracy, but it didn't. I didn't use the plate they provided as was kind of flimsy, and that may be why. The platform of milk crates allows water to be drawn up from below without anything there to block it. Even 22" up they still turn the whole pond over.

Think I'll find something to mount under the diffusers and see if that helps. Preferably something that won't try to float.

Tom,
I've been considering something along those lines too. Just don't know if I want to see big pink sheets floating on the pond. It's right outside the front door. Maybe some kind of floating island tho.

That's some good information TGW! I am assuming the "87 last year top to bottom" did not kill any fish which should relieve those that are approaching such temperatures.

and, The fact that you have established a thermocline by raising the diffusers is promising. My deepest diffuser is about 20 inches off the bottom, but no thermocline to speak of has developed.

I look forward to the repair of your D0 meter.

EDIT: I would be concerned if too many pink sheets were used. It would reduce the water to air interface. I wonder what a "rule of thumb" ratio would be?

I used 1 sheet to make a pair of 2x4 turtle/duck floats and covered them with green indoor/outdoor carpet as that's what I had on hand. Lot's of variations on that theme to hide them if they were to be permanent. I don't really need the additional shade though except around mid-day as I've got trees circling the pond.

I'll pull mine out of the water once it start to ice over but you probably don't have to deal with that issue so aesthetics may be more of an issue.

QTR A, yes the 87 temps were from last year with the diffusers running 24/7 and the diffusers were set on bottom. This year I used rebar to build 4-4 legged stands or lets just call them tables and set the diffusers on them. I left two diffusers on bottom in the 7 depths. So most all of the diffusers are at the same level or depths in the pond. I also went to running them from 9pm to 10am instead of 24/7. Last year in the heat of the summer I found 3 dead and floating lmb. This year no dead floaters. And I am not so sure I would call what I have now a true thermocline but more like just some cooler water on or near the bottom. From my experience a thermocline here is where the water is a lot colder, based from my scuba diving experiences. When scuba diving the thermocline water temps are so cold I just can't swim there, even when wearing wet suits.