Pond Boss Forums AERATION Systems questions Keeping my fingers crossed!

I turned off my aerator yesterday -- almost exactly 24 hours ago. It had been running nonstop since late September 2002.
This year I thought I would finally heed the collective wisdom on this site and give it a try.
My pond is fairly small -- only 1/4 acre. It's spring fed and the incoming flow is always about 53-54 degrees F. Here's a snapshot of the little creek right after it emerges from the ground. It's about a foot wide and a few inches deep, and its flow has been very constant.



This view shows the marshy little spring stream where it flows into the pond (looking west here).



I still can't get used to not seeing the column of bubbles rising at what would be the center of this picture. The pond lies at about 1,160 feet elevation msl. The combined effects of the spring water and aeration usually kept it about 95-99% ice-free throughout the winter. In a couple of little leeward coves there might be some ice cover when the air temperature drops to zero. But usually the pond is ice-free and crystal clear all winter. So clear, in fact, that I still seem to get some chara growth even in the dead of winter (Any suggestions on winter control?)



Here's a closer view of one of the chara beds. They seem to produce a fair amount of bug life, but that's about all the good I can say for them. The pond has some decent size rainbows that manage to make it through our warm Virginia summers -- and I added 40 8" brook trout last week. When I got this place almost five years ago, the pond had some very skinny channel cats (now very well fed); some good hyrbid sunfish (again, doing fine) and some little largemouths (still pretty much runts). And then there are the eight (yes, 8 -- stocked by a former owner) huge grass carp ... that don't seem to care too much for chara.



One last note about turning off my aerator (can you tell I miss it!?): The bubble column continued a good 2 - 3 minutes after I pulled the plug. Is that normal? Now, I've got the balance of the winter months to figure out how to install the replacment parts called for in the routine maintenance for the aerator. Wish me luck. I'm not too mechanically inclined. -- Mike

Hi Mike -
You have an absolutely beautiful pond.
Just be sure to keep the snow off the ice this winter. Shallow weedy ponds are the most in danger of winter fishkill. You should go ahead and do the maitenance on the compressor so you can have it ready to go if you have a bad winter.

Hi Mike....quick question on your carp. Could it be that they are eating some of the chara? They are obviously eating something or they would not be alive. I am very impressed with your pond. The clarity is awesome. I am sure the aeration has helped greatly with your water quality. We are adding a display aerator this spring to our pond which has very poor clarity. I am hoping that will improve. Good luck with your aerator.

Sue and Illinois Longhorn --

Many thanks for the kind words about my pond. I love the clarity of the water, too, but the credit I think goes to Mother Nature -- probably to the chara, in fact. From what I've read, it seems to really capture and use available nutrients (maybe at the expense of other plants and critters).

I'm sure the grass carp do consume some of the chara. The literature I've been able to find online suggests that as grass carp get larger (especially beyond 18" - 20") they seem to switch from algae to vascular plants. I've watched them working around the base of the cattails, and have concluded they may be nibbling at buds or shoots coming off the root system. But it's only a guess ... have to figure out a sure-fire way to harvest one! It's not easy sneaking up on them with water that clear.
By the way, if you want to see what this pond looks like after a 5" rain (and before my neighbor had good silt guards installed at his construction site), just check the posting I did back in October in the "Muddy Water" category, with the sub-head "Trout and Muddy Water."
I think aeration has been a really important part of achieving and maintaining water clarity -- but I think upper watershed protection is paramount. I try to keep 100% vegetative cover up by the spring and its basin; and I don't graze any livestock up there either.
I've also tried, with varying degrees of success, several different commercial bacteria cultures to work on the pond's "muck." I really haven't been bowled over by any one product -- and some are almost outrageously expensive.
But bottom line, it was the aeration system that started the big turn-around on this once warm and weedy pond. And I credit it with making it a trout pond, too -- especially on those muggy July andAugust nights when all that chara starts using dissolved oxygen, instead of giving it off.
My radical plan for next summer? Maybe just running my aeration at night instead of 24/7.
Again, thanks for the kind words about the pond. -- Mike

I'm not nearly as knowledgable as some of the great aeration experts on this forum, but I'd be a little cautious about running an aerator for trout just at night. I've managed one trout pond this way and we found that a cloud of debris and black colored water would be lifted off the bottom for an hour or two after the aerator fired up. This seemed to be stressful on the trout, however I was not priveleged to follow up long term on the project. What I do on my best pond is run a surface agitator that is 1/2 hp just at night. That way I get the benefit of improved O2 to counter nighttime plant respiration, without disturbing the thermocline or pulling cruddy water off the bottom. I took careful O2 measurements all summer long and had an exceptional O2 profile that allowed my yellow perch to survive the entire summer. Of course trout are a little different animal.....

ML, Not knowing what aeration system you have and considering they vary greatly in circulation rates Ill suggest the following just so you dont get caught in a bad situation as trout always concern me.Many of the posts on winter aeration are made with logistics in mind. So that needs to be factored in when making adjustments to your own needs.The need for winter aeration can and does differ from pond to pond even when located in the same general location. I know you have a different climate than we do here in Ohio. My son is stationed in Norfolk and I know he has a lot milder climate than we do and I believe you are somewhat north and west of there. Considering that and in your situation I might do one of a few simple things.Simply slow down the existing diffuser by venting a lot of the pump cfm to the air. If you ran at 5 psi take it to 1-2 psi for example, or add a second diffuser in an off set part of the pond in 4 ft of water and aerate with that instead or move the existing diffuser to the same shallow water. If adding a vent to the existing system is confusing let me know and Ill be glad to step you through it, simple plumbing can be bought locally for about $5-$7, If you want to add an off set diffuser let me know that also as I have "many" diffusers that we have removed over the years that did not perform as main diffusers and you can have one of them,(another benefit posting on PB) they work great as winter diffusers.Bruce is correct in his comments on less than 24/7 running, some diffusers can pull from the bottom too much "crud" just from the short time the system has been off.Your water seems very clean however and you can thank the water temps and chara for that. Some diffusers are designed with the above in mind and have specific bases built that put the diffusers x number of inches of the bottom to avoid this.Good Luck

Bruce and Ted --

Bruce and Ted --
Oops. Hit the post button too soon!

Many thanks for your advice -- it is greatly appreciated. I think one of my goals for next summer was simply to cut the electric use and hence lower the monthly electric bill during the AC season. But the aerator really doesn't cost that much to run 24/7 -- and trying to run it part time looks like it could turn out to be a case of "penny wise, pound foolish."

I don't know too much about the mechanics of aeration. The unit I have is (I believe) a 1/3 hp unit that moves 1.5 cubic feet of air per minute, and pulls 3.1 amps. I have it located in a slightly offset position in the pond -- not at the deepest point but in about 6 feet of water (deepest is about 8' or so), in what looks like it might be the old spring stream channel. Believe me, it was a totally random "drop" back in September 2002! Probably influenced more by biting insects than by pond knowledge.

That idea of a second diffuser is pretty intriguing. Since most of the trout head up to a small area where the spring meets the pond and spend much of the summer there (most of July and almost all of August), that might be an ideal location for the second diffuser. That area seem to be the cold water "plume" -- a habitat usually no more than about 25 feet out into the pond; about three feet wide and 1.5' deep where it enters and widening to about 12 feet and maybe 3 feet deep -- that seems to be their "refuge." I know that my spring water emerges very low in DO and very high in nitrogen, so that sounds like the place for a secondary diffuser. (Note -- tried a little home aquarium type aerator up there two summers ago ... it didn't last but a week in the rigors of the outdoors.)

In the meantime, I know I'm going to be busy this winter "rebuilding" the aerator, hauling out the air stones and cleaning them, etc.

One comment about our climate: I grew up in southwestern Ohio, so I would say this climate is generally milder. We get some sub-zero weather in winter, but those days are far less common than days in the 50's. Then in the summer, we can get some 95+ days, but it almost always cools off well at night. I think that's the big difference a mountain climate offers. While my place isn't too high in elevation, it gets the benefits of the surrounding regional mountain climate. Night-time temps here often dip into the upper 50's -- that may be a big difference for trout survival, too.

My thanks again for your excellent advice. I'm not going to rush into anything (after all, it took me two years to decide to stop winter aeration!). I'm going to proceed slowly, ask a lot of questions and see what my aging back and thinning wallet can accomplish. -- Mike

ML, Ted, Bruce and Sue all gave you some food for thought. If I may, I would like to add my experience with trout in the NC mountains. We experimented with the night only option and as Bruce mentioned, we had plooms of hydrogen sulfide still be lifted when the system was first turned on each day.

This clients pond is 30' deep and has a stream feeding it all year. I think depth played a big roll in the amount of decomposed debris on the bottom of this pond as well as the surrounding trees that defoliate each year. We simply were not meeting the oxygen demand of the pond by simply running the system 12 hours each day. I would suggest at spring start up, running the system all day especially with the heavy chara load you have. That chara will consume oxygen at night and if you do not have enough oxygen "in the bank" you may wake up to a nightmear.

As for setting a diffuser where the spring enters your pond, as you described, the trout are there for the colder water. If you add a diffuser there, you may tend to bring the warmer water from the pond and mix it up with the colder water making it too warm for the trout. I would see if you could make a rip rap out of the stream to add oxygen as the water breaks over the rocks before it enters the pond.

If you wanted to experiment in the spring before the trout need to use that area for refuge, we could send you a sample of our watergarden diffuser (smaller than an AirPod diffuser for the lake) and take temperature readings throughout the day to see how much that diffuser affects the temperature.

Just some more food for thought as you wait out this winter. By the way, 15 degrees here right now with snow flurries. Here is a photo of our clients trout pond.



Trout Pond Video

Cary -- Many thanks for the input and the suggestion about the smaller watergarden diffuser. That could work. I've been concerned for a while about the whole DO trade-off: get the oxygen up and you risk a potentially lethal boost in temprature; but go with stratification and the DO is gone in no time at all from the colder depths ... and the trout are toast.

My pond is marginal trout habitat, to be sure. The spring is steady but really doen't have the volume I would like. Its strong point, according to a local spring expert (this is karst country around here), is that the spring is a deep one, as opposed to a shallow, bluff-type spring that might be adversely affected by droughts and wet seasons. The flip side to that is that the water has almost no dissolved oxygen when it emerges; plus, it is very high in saturated nitrogen -- and total hardness is way up there, too, something like 450 to 500 parts per millions, if memory serves me well.

I'd like to be able to boost DO right up near the spring or near where it enters the pond (about 70-75' away) without bumping the temperature up too much. Unfortunately, there just doesn't seem to be sufficient gradient or fall to create a riffle area that would do any good.

I've discovered a place online that deals in submersible automated data loggers that plot temperature over varying intervals -- and they seem to be fairly reasonable (I'm a retiree and watch my pennies pretty closely!). I guess if I got two data loggers, one could be placed up in the spring channel and another in the zone where the trout hang out in July and August, and that could give me a very good profile of how much temperature gain there is in that span of 100 linear feet or so from the spring to the far end of the trout zone in the pond. That might give me a better picture on where and how to place a small diffuser.

My wife and I have a "grand plan" for the pond that includes putting up a small cabin-style storage building on a little peninsula, bordered on one side where the spring enters. We'll have a new electric line run out there, and then move the aerator to this storage building (it's been up in a shed about 150 yards above and away from the pond). We might also put an old PC in it to receive data from the data loggers ... bold plans, indeed, for a decidely low-tech, non-handy old guy! So, stay tuned.

By the way, that pond depicted in your post is absolutely beautiful! I take it that it's up at a pretty high elevation? -- Mike