Pond Boss Forums AERATION Should I aerate? What's Your Thermocline here in Mid-May 2006?

Wondering for mid-western and Michigan Pond Bosses - what's your thermocline now that we are in mid-May 2006. What are your surface and bottom temps these days??? Trying to get a read on what's normal?

Just re-stocked rainbow trout in late March (doing great and growing fast!) in West Branch, Michigan (2/3 way up the lower peninsula of MI). 1/3 acre pond, 1/3 of pond is 12-14 ft., rest is 4-8ft. depth.

I currently have no thermocline (surprise). Have a two diffuser aerator system that I have on a timer running from 11:00pm to 8:00am. still. DO levels are at 10-11. Uniform water temp is at 60 degrees. I have about 20 gpm running into the pond 24/7 from an artesian well (constant 48 degrees). I plan on moving the aerators to the shallower depths (5 ft.).

My goal is to keep those temps down as much as possible (July can have some 90 degree days) to keep the trout alive.

What is a "normal" coldest part of thermocline temp in mid-May? Any advice?

I would think it's too early to have a pronounced thermocline especially in Michigan. From my experience you need some hot weather which we haven't had yet. I really don't think you'd see one in a pond that has NO diffusers until June but I could be wrong.

Of course you shouldn't really form a thermocline if you are running diffusers should you? Isn't the whole point in putting diffusers in is to break up the water column not allowing a thermocline to form?


1/3 acre pond and only 20 gpms?

I'm trying to getting a reading / gauge on what other Pondbosses have expereinced as a normal development of a thermocline. Your input was helpful.

With only 17 gpm, I recently had a 2" steel pipe artesian well put in (3 weeks ago) and sadly the output is only a mere 3-4 gpm (less than half of a garden hose . with the old artesian (17gpm + the new one (felt like a waste of $$$) that adds up to only 20gpm . All these drillers were hesitant to drill the 8" hole and do the 5" pvc pipe because there is an artesian well on an adjacent property that was kicking 50 gpm (a well less than 600 ft. away). It was throttled back, as it is only for a building / small business and not needed. So, them being overly conservative, they only agreed to the old fashioned impact 2" well (mymistake!).

I am going to experiment with a cheap test well pump that runs at 10 GPM and insert a suction pipe down about 10-15 ft. and see if the flow will be able to keep up with doubling the output to 10 gpm or 600gph. My ultimate solution ($350 though) is to install a 35-40 gpm shallow well pump and have it kick in based on a timer - ON during the daytime during June, July, August.

As a protective measure, I will also be installing a 220v capable Johnson Controls A419 temperature controller on my aeration system. It will kick in when the air temp drops below about 58 degrees (fully programmable with a differential range of a whole 30 degrees!)and shut off when air temp is above 58 degrees.

I searched for months looking for this kind of device. It is nornally used in refrigeration and green houses. At only $55 it will automate cooling the pond either at night or whenver the temp drops less than 58 (or whatever I set it to.

Question - is 58 a good set point? As a fellow trout pond boss, what temp range are you able to keep your pond in the summer??? How much risk is ther of going above the dreaded 70 degrees??? I lost 200 trout three years ago (little knowledge base)when I left the aerator on full time into June (I know better now). Your pespective is appreciated

As of May 09, 2006 I have uniform water temps throughout my water column of 59.5 degrees F. I am located in southeast Nebraska. If my aerators only kicked on below 58 degrees there would be long, long periods of time between aeration events during the summer. During this time there would be a buildup of bad gasses and anoxia in the hypolimnion that would be released during aeration and probably result in a net loss of dissolved oxygen. I would be inclined to look at options that would add oxygen to the well water and distribute to the hypolimnion directly. Then I would buy a surface agitator from a company such as Kasco to aerate epilimnionic waters. This would allow the thermocline to stay put, but keep all areas of the pond habitable to salmonids. According to Cecil's previous post (IIRC), salmonids will often die of anoxia before they die from warm water stress. Aquatic ecosystems may have a device that would measure DO at the thermocline and kick on your surface agitator if your DO drops below 6 ppm. All of this is based on your lack of available water volume. I can dump 40-50 gpm of 54 degree water in my ponds in the summer and I'm not even certain I can keep yellow perch alive in my .15 acre pond. This could be looked upon as a "available well water (cooling) to pond water volume ratio". Cecil's is even better than mine and it allows him to overwhelm the summertime solar heating effect that will kill your trout. If this ratio is low you may be tip-toeing a windy ledge.

Well the problem is we are comparing apples to oranges here. That is, my pond is only 1/10th acre so the cooler water entering has less volume to cool or keep cool. Addtionally I have more flow -- at least 38 gpms. My rule of thumb has been to shut off the diffuser aeraton when air temps reach 80 F. during the day, but I have took it a step farther in my previous trout pond and only ran the diffusion aeration at night in summer, as there was an algae bloom during the day that produced oxygen.

In all fairness my present trout pond is not the same one I had in the past. This one is slightly shallower and narrower but it still has steep sides and it still is about 1/10th acre. It's more retangular shaped then the other more round one. It's about 90 feet long with the deep end of 8 feet about 40 feet wide and the inflow end only 25 feet wide where is is only about 4 feet deep. The bottom slopes to the deep end to to facilitate draining and I will be spanning a shade cloth over the shallower end to reduce further warming.

58 for a cut off sounds a bit low to me but I could be wrong. I would up it to the air temps of the upper 60's or lower 70's. You can always change it if you deem it necessary. In my previous pond even when air temps went up to the 90's in summer my pond never went above the mid 60's on the surface. I did reach the upper 60's on really hot days around the shallow edge but that dropped again after the sun started to drop in the afternoon. I think I lucked out as it turnd out to have perfect temps for trout growth.

Thanks for the posts! A few elements I am banking on are: 1) my grandfather stocked several thousand rainbow trout fingerlings 40 years ago (I being a bit younger)and raised them successfully over a three period to be 16-20" beauties. He had no electricity, no aeration and the exact same artesian well 2" steel pipe putting out 15-18 gpm, that's it. He had a few winter kills I am sure, and not sure of summer kills (but he had a hardy trout population in July and August when we used to harvest them (there were hundreds in there and we watched them be hand fed. since this is 2 hours North from home, we have a Sweeney auto feeder programmed to feed twice a day at prescribed amounts (per published feed charts)

The pond was only 8 1/2 ft. deep at it deepest spot and gradually sloped to 4 and then 2 ft.at the edges. As of lsat summer (excavation) the pond now is 13-14 feet in perhaps a 1/4 to one third. so pond voume is probably increased by 1/4 and some decent deep pocket areas etc.

Three years ago when we failed, the temps were 72 and up to 75 at the surface, lots of algae bloom AND (I beleive this to be the FATAL mistake) we kept the aerators going 24/7 into mid June which cooked the water. Fish were swimming like sharks at the surface, a dozen or more had actually jumped out onto the banks- it was ugly! Imagine having a oversized aeration system turning the water over once a day or more in 75 / 80 / 84 and even 86 degree temps- Seems to me I did a good job of convection cooking the water and the trout? Lvie and learn and PAY! Never heard of pond boss back then.

At that point I shut off the aerator (too late of course) and stopped feeding, as they wouldn't eat anything at this point. It was all over in less than a week- gone. Experienced TLS for the first time (trout loss syndrome)

Are you saying it was anoxia? Was it anoxia related to high water temps? Maybe I should look at the threshold temp for turning on the diffusers at 64 or less?

Also, I have noticed that the historic weather charts show that 80% of summer nights in West Branch do drop into the 50's and often into the high 40's for some nice cooling effect. I am hoping to capitalize on this, since I ahve a 1/4 hp / two diffuser system (which is designed for up to 1 acre ponds.

Any additional thoughts?

I am Michel's brother and I installed the outside air-temp sensor and aerator controller last weekend. The unit is currentlysetup to turn on when the temp dropped to 58 or below and then off when the air temp exceeds 60 degrees. It seems to work well at these temps for the early summer since the recent night time temps have been from the mid forties to mid 50's so we are getting anywhere from 6-10 hrs of aerator action per night.

We hope that churning the water and exposing more of the water to the cool night air will help in keeping the pond cool. Even though we have a 1/3 acre pond, the aerator is oversized with two large diffusers and a 1/3HP 230v rotary vane pump with approx 6 cfm flow. Conversely shuting the unit off when the air temp gets hotter should help. The temp air temp controller is only about as expensive as an intermatic timer. My brother bought it on the net for about $60.

Well, Juen is a bit different than May with pond bottom temps at 68-70! (Ouch!) Trout are still thriving. We added a new 2" steel pipe well and jsut added a 3/4 hp pump to get mroe water out of it. I think we're getting about 30 gpm compared to 18 gpm we used to get. That is helping, but I'm thinking the water clarity (only about 3 ft. clear and 6 ft. max) is partially responsible for too much solar heat reflecting and absorbing into the pond.

An important note si that we have an output pipe that was above the water level by 4 inches. We had put an extender on it a few years back to fill up the pond right to the top of the banks, but after the excavation work, there are slow leaks and it hasn't perfectly sealed at the highest level. SO- I recently removed the 6" inch PVC extender "S" curve and now the surface water is draining! I am guessing that will be much healthier for the pond and effectively skim the warmest water off the top, since about 40,000 gallons is going in on the other end of the pond each day. Should help support more natural movement of water.

QUESTION- would limited water clarity be primarily responsible having a strong solar heating effect. Pind size agian is 1/3 acre (60 x 225 ft.) and is average depth of 6 ft. with 1/3 of bottom depth at 10-14 ft. P.S. I have turned off the aerator (for 2 weeks during a construction phase of equipment inthe storage box we have), since there are two well splashing water onto the surface. I plan on re-connnecting it and running it at 62 degrees or lower for supplemental O2. Final note- the rainbow trout are now 13-15" and very healthy. Stocked 200, guessing we have 175.

Mike,

What color is the water? Greenish, brownish what?

Mike, Where in this long narrow pond are the well inlet and over flow outlet?. One at each end or one on each side or both at one end maybe across from each other?.