Pond Boss Forums AERATION Systems questions Aeration of pond - post mortem

When the ice melted this spring I was horrified to find that our well stocked bass pond had become a scene from a Stephen King novel. All of our fish had died. In previous years I had noted no more than one visible fatality.

The pond is about 18 years old and spring fed. Bullrush occupy the two far corners and I usually keep the three sides facing the house trimmed so the kids can fish. In the winter I usually clear the snow to allow for pond hockey; however, this past winter was really sucky and I didn't blow off the snow. The pond is teaming with life - frogs of many species, snappers, blue herron, creepy muskrat, and hundreds of Canada geese in the wetlands behind our home.

I am buidling a system to aerate the pond which is about two thirds the size of a hockey rink and up to 25' deep. Estimated at 425,000 gallons. I have a Gast 1/4hp rotary vane compressor and a T-tube style diffuser that is 2 1/2" in diameter and 24" long with a 3/4" MNPT stainless steel inlet. Also, I have 5/8" heavy tubing AND I am going to build an array of four 9" FlexAir disc difussers. Overkill? Maybe, from what I have read.

The bottom has seen an increase of weed growth and has become steadily murkier over the past few years. There is no foul odour; however, when I rake the weeds the black muck does smell pretty bad. In additon there is a large release of gasses as I rake the bottom.

Do you guys think the WHOLE system will be overkill, or am I on the right track.

OH! Almost forgot, I restocked the pond with 100 rainbow trout. They are ellusive though, I hardly ever see them and I have only tried to catch them with a yellow jig (barbless). They are REALLY well fed with the abundance of tadpoles and whistling frogs.

Cheers!

AZ, I think we can relate to each other in that I am in Minnesota where things freeze over pretty good. Based on what I know you are on the right track. I consulted some experts when I built my 1/2 acre pond (100 x 400 feet)and immediately determined that I need winter aeration to avoid winter kill. You need to be careful with winter aeration in our cold climates though since if you cool the water too much I've been told the fish will be unable to aspirate oxygen and will die even if there is plenty of it. I've been told this occurs if the bulk of the water gets down to 39 deg. F. So the answer in my case was that before I put fish in my pond I aerated the pond for the previous winter. I experimented with how much time per day I could aerate and not get all the water that cold. I also use a vane pump, 1/2 HP that pumps about 5 to 6 CFM I think. I determined that when really cold I cannot run this for more than 8 hours per day without taking too much heat out. So I run the air pump for 4 hours starting at noon and then for 4 hours starting at midnight. Now since you also want to get as much O2 in the pond during that time as possible I would not use a diaphram diffuser, I would use some good air stones. I bought some stones from Aquatic Ecosystems. They have data in their catalog that can help you calculate BOD and compare what you need to how much your pump and diffuser will put into the pond. I must say that once I determined my pump running time and calculated how many air stones to hook into the system I have run the thing through 3 winters already with not so much as one dead fish evident in the spring or summer. I run the same aerator schedule all year. My pond is very heavily stocked with 1000 HBG and some bass. I also made the mistake of putting a few crappie into the pond and now have many hundreds if not thousands of them. My bluegill and larger crappie are 3/4 pound this year and very healthy. Also note that I put my diffusers on the bottom of my pond in deepest water (8 ft) to keep things from stratifying. I think this gives the fish more livable space. Hope things work for you. Hopefully some of the real experts on this forum will chime in and let you know if I've given an bad advice.

Thanks for the input. I'm really unhappy with the trout (pout) they seldom make their presense known, unlike the (now dead) smallmouth bass. Sure, they pick the occasional dragonfly off the surface, but don't leave the surface and crash back with a splash. Sigh...

The local fishfarm is an hour away and they have been lazy in catching and penning the bass. So I may have to catch and stock up the old fashioned way.

Oh, I have also ordered an Otterbine 1/6hp starburst floating fountain which I will install mostly for aesthetics; however, I'm hoping it will improve water quality as well.

Cheers! AZ

AZ, sorry to hear about your fish kill. Take some time and read the discussions regarding winter aeration in this thread, lots of good info.
http://www.pondboss.com/ubb/ultimatebb.php?ubb=get_topic;f=20;t=001274

Excellent thread, thanks for the link. I may suspend the larger diffuser a few feet below the surface at the far end of the pond. Perhaps using a smaller compressor, saving on power consumption and to avoid over-chilling the water column.

The open area will allow me to drop a water pump into the pond and flood the remaining surface for ice hockey. Go Leafs!

I noticed this morning that about half a dozen trout were floating on the surface of the pond.

My aeration system is incomplete, with the tubing and disc difussers on a truck in Syracuse, NY., and the compressor on my desk in Toronto. I'm hoping it's not too late to save the remaining fish.

Hope you can save most of them AZ. Its gotta really hurt to see something you worked so hard for die off. I hate to think about it but I keep thinking that my day will come. It's just been going too well for my first shot at this.

I have since dug a trench through 60' of hard-packed clay and run a 240 volt line to the pond.

The floating fountain from Aquaticeco.com is very pleasing aesthetically; however, the Gast 1/4hp rotary vane compressor from C&H sales was DOA. I have sent two emails and they have yet to respond. Curious to know if anyone else has had difficulty in dealing with them.

So... I have some splash and movement but no bottom aeration. The good thing is that there has been no die-off in the past week despite some very warm weather.

I am still waiting for the replacement compressor to arrive from C&H Sales (they are sending another unit free of charge); however, the floating fountain has been operating non-stop for three weeks without any problems. The surface is constantly moving and it seems that the pond is responding to the increased oxygen levels.

The pond is very deep and I cannot imagine that the fountain will have much effect on de-stratification without the use of a bottom aerator.

On a brighter note, I caught a smallmouth bass yesterday! I can only assume that there are more that survived. The trout are a mystery though... I have not seen any swimming and only rarely do they break the surface to catch bugs. The pond is teaming with all manner of frogs and flying insects so I can only surmise that a well fed trout is a happy (and elusive) trout. Alas, they are freaking boring compared to the bass that would chase a bulrush stem and splash down after catching an unfortunate dragonfly.

Well, after several calls to the supplier I got the Gast pump replaced and finally installed the diffuser last Wednesday. It's now running 24/7 at a depth of 20 + feet with a good boil. I have plenty of weighted hose left and may install an array of 9" diffusers at the opposite end of the pond.

I have noticed a slight difference in the clarity of the water, although it might be just wishful thinking.

I was wondering what the turnover rate would be for the current system and what the rate would be if I were to install the array of 9" round diffusers.

I'll try and post some pics.

A Zone do you have a Gast 0523 ? 10psi model by any chance, Ted

The model is: ROTARY VANE AIR COMPRESSOR GAST MODEL . #0522-P177-G21 DX. Oil-less rotary vane air compressor directly connected to motor. Compressor is rated 2.8 cfm @ 10 psig max. Motor is 1/4 hp 220 VAC 50 Hz 2.75 amps. Single phase. 1425 rpm.

The compressor has been running for nearly two weeks straight without any glitches. I have not noticed any changes in the clarity of the water nor the creatures living within the pond.

The rainbows I put in last year refuse to be caught and have not been seen. I have noticed some small fry that are two 1/2" long, very dark in colour and aggressive when dew worms are offered. Could these be some survivors of the kill?

Ability,

From what I know (but not from exp) is that during any major fish kill. It's amazing what does survive that you do not see. Very rarely does a fish kill, kill all the species in the pond.

The only fish inhabitants prior to the kill-off were small mouth bass and after the kill I added 100 rainbow trout. I caught a bass in the fall, so at least one survived. The trout, which I might add, are REALLY boring and annoying. I never catch or see the buggers! The heron and muskrat have gotten a few I'm sure and perhaps four or five died over the summer. No floaters in the spring.

I am going to try and get about 50-75 SMB from a local fish farm in Erin, Ontario in the summer.

Cheers!

AZ, Consider monitoring the water temp from top to bottom in the summer heat, The 10 psi model will have a shortened life at 20 plus ft of depth. Moving it to shallower water will increase pump life and probably trout life too.Hopefully your spring keeps you cool enough with your current setup, Ted

AZ - Since you are in the north (southern Ontario) and water temps are still fairly cool, I have had good success putting the diffusers on a stand or frame that gets them off the bottom and yet still in the deep basin into around 17-18 ft of water. This will reduce the operating pressure of your compressor to around 8.5-9 psi and this will lengthen the life of the vanes and bearings. When you start aerating in spring with diffusers on a stand while pond is still unstratified the entire water column of smaller ponds will become completely mixed.

I'd like to enter the conversation. I have a 1/3 acre pond 60 x 225 with depths averaging 6 ft. and deepest corridor at 12-14 ft. Stocked with Rainbows and there are challenges.

My pond is struggling on the edge with the 200 10-12" rainbows put in around March now at a healthy 14-15", but the temps up to 68-70 degrees (ouch!) I installed a pump to give me up to 30 gpm of 50 degree water, but that is not much in reality. It ends up being over 40,000 gallons / day, but only a 5% exchange of the 800,000 overall capacity.

The big deal with rainbows is temp and dissolved oxygen. The top temp for trout is 70 and at 72 / 73 they die off within a matter of hours. A regular cold flow of water into the pond is almost essential. What is your bottom temp and surface temp? And,what size were the rainbows when you stocked them?

Sorry for the delay. The pond is spring fed and the bottom temp is quite cool. There is no danger of the water becoming too warm. I elevated the difusser to the 18' mark and the pump is still running quite well.

Is it common to not see the rainbows at all? I really have not tried seriously to fish any out. Maybe three quarters of an hour with a few worms. I would assume that they are still there as other creatures such as water-bugs, frogs and tadpoles are not running rampant. Last spring and summer it was writhing with these creatures until I dumped the trout into the mix.