Pond Boss Forums AERATION Should I aerate? River fed pond

Greetings.

Looking for some advice.

A few years ago we built a 1.4 acre pond on some land we own near a river that we also decided to put a house on (mid state of South Carolina). The water source for the pond is from a river that our property sits near.

Over the first few years the pond was filled and drained a few times due to leaks in the vertical overflow pipe.

The last time we drained the pond we removed the vertical overflow pipe for a siphon system. The leak issue was finally fixed and we filled the pond one last time.

With the house finished and the pond fixed, we consulted with a local pond company and they installed 3 bottom aerators and did an initial stocking.Since then we have noticed issues that we had not experienced before we put the aerators in or stocked the pond.

First thing we noticed after the stocking was blue green algae forming on the pond. The pond company came out and treated that and the blue/green disappeared. But then we developed a duck weed problem and during this time all the tadpoles we had in the pond died and so did the mosquito minnows and bream we had stocked weeks earlier in the year.

Currently we still have the duckweed issue, see no life in the pond.

In the past we would suck up all sorts of minnows/fish from the river and they thrived in the pond until we drained it. We did not have much if any blue green algae or duckweed. The pond was filled for months (like now) and we did not have the issues we have now.

The only differences from before are the aerators and the stocking. The river is considered fairly healthy though I am sure there is runoff (and all that brings with it) from farms that run its 500 mile length.

Could the aerators be causing the issue? Or maybe the stocking introduced something?

We keep the pond topped off with river water, which we probably do once every couple of weeks. The pond has a solid clay bottom and as mentioned before is about 1.4 acres with depths that run from 2' to 15'.

Pond company is coming out to take a sample and test it.

Thanks!

I think you should be testing the pond water during a blue/green bloom (Cyanobacteria), not testing during non-bloom times. Monitor (record) when the blooms occur to see if there is a seasonal pattern or after water filling. During the bloom time also test the water that is being used to fill or what is in the river nutrient wise to fill the pond. IMO the bloom would most likely occur due to a pre-river water filling event - thus the reason for monitoring of filling and timing of blooms. Upstream dischages into the river could be fertilizing the blooms and possibly be introducing contaminants suppressing aquatic life. Certain B/G blooms can at times also produce toxins that can suppress aquatic life forms. When the B/G cells lyse (decompose) is when they release their toxins. Kill all at once can be problematic. Remove one plant and release of nutrients can stimulate another plant specie. Mgmt company should know this if they are competent. Sometimes a B/G specie may or may not produce toxins depending on water nutrient content as it is known by current science knowledge.


After the initial test by the company return here to report the results and their suggestion/s. Then it might be a good idea to do our own testing by getting a LaMonte chemical test kit for just primarily nitrogen and phosphorus to do your frequent needs for testing of fill water events and bloom events. Fill when N-P is low in river. The (N&P) ratio are the 2 main chemicals that usually stimulate blue-green (cyanobacterial) blooms. When you have another b/g bloom it should be analyzed microscopically for what the specific specie b/g is causing it. I do that - PM me. Almost always the blooms are predominately one specie sometimes stimulated be certain nutrient ratio conditions. Once the nutrients are introduced into pond it is very difficult to get them back out. Blooms of something will always want to develop,

I will post once we have the test results and recommendations.

Thank you for your time, the education and the advice.

Did you get the water test results back yet?

The aeration system should not be the cause of the problem. The only time I have seen an aeration system kill fish in a pond is when the owner didn't start up the system correctly and mixed too much of the anoxic bottom water with the upper water column, killing the fish.

Duckweed is an indicator of high nutrient levels and very little wind on the surface of the pond. Usually water that stays in a pond builds up nutrients. Draining and re-filling the pond should flush out the nutrients. I agree with Bill Cody 1,000% that you should get the river water tested for nutrient levels. Toxic Blue Green (B/G) algae needs specific parameters to grow. There are many, MANY different species of B/G algae but VERY FEW are toxic. Just because someone says you have B/G algae doesn't mean that it's toxic.

We have not received the results yet. I emailed the company and they said this week but we did not hear back yet.

They treated the B/G algae and that went away, then they treated the duckweed when they took the samples and that went away. Though it just started coming back a couple of days ago.

The pond is part of the yard and our new home sits close by. We are basically having to use the river water almost weekly to keep the pond water level up so low water level doesn't detract from the house. Have to see it to appreciate what I am saying.

Regardless we will constantly be pulling water from the river so anything we do has to work around that fact.

The pond receives lots of wind. It sits on a a bluff facing west over looking a river. The only reason I brought up the aeration is because its really the only thing that has changed. Ever since it was introduced nothing lives in the pond. Maybe something changed with the river but timing wise it would be a heck of a coincidence.

We just received our test results back.

It says that the pond is in a borderline mesotrophic state. Also states that the dissolved oxygen levels are excellent due to aeration. The pH is slightly low (6.0) and that ideal PH is around 7.2.

Pond company suggestions...To help balance pH, use a liquid form of lime(?), as it reacts faster than agricultural lime powder. They will use a phosphorus binder along with algaecides to take care of the current algae. That's all I have been told so far.

No testing to backup or verify this comment, but I wonder how well the duration effects of liquid lime vs using granular slower dissolving agricultural lime? I understand applying the liquid form is easier, more convenient and quicker but has there been research as to how long it lasts in a pond compared to using the granular form? Pond sediment chemistry and flow can have influences on longevity of the alkalinity results.

I had to look up "mesotrophic," but that just means not too low or not too high as far as nutrient load.

It doesn't explain the fish kill you had.

The kill may have been due to the blue/green algae, or the aeration bringing up some bad water, or some other reason.

We really don't have to worry about adding lime to ponds here, BUT we do have to lime the soil for agriculture and deer food plots. The liquid lime has to be added two or three times per year to keep the pH optimal, the powdered agricultural lime only has to be applied once. I am not a fan of liquid lime, why pay for water? If the pH change is too rapid, it can kill fish too.

In regards to pH. What time of day was the water sample taken? Ponds typically see a bell shaped curve during the day in regards to pH levels, and the pH swings more daily when alkalinity and it's buffering capacity is low.

This is about soils, but the same principle can be applied to water: Buffer

O2 readings are typically taken immediately.as that can change after the sample is taken.

What were your water test numbers? What did they test for?

I think the test was taken around midday.

I'll have to ask the pond guy exactly what he was testing for but just mentioned he would take water samples and send it to a lab where they would come back with recommendations based on the results.

I wonder how the constant use of river water to keep the pond at a certain level impacts things with the pond. Last Spring we had a ton of critters pumped into the pond that lived well for weeks. Baby gar, green sunfish, tons of frogs,etc. But as I wrote before, ever since the draining, refilling and added aerators, nothing much survives. We saw almost all the bream and mosquito minnows die as well as all the tadpoles and frogs.

What I've been told and read online suggest aeration should not cause any issues unless the pond was already established and was not introduced correctly (ie, just turned on and left that way). Not sure what else it could be.

We do have to pump water in every week or so we run the pump overnight. It has been pretty dry in our state this winter. I attached a couple of drone pics to show the pond. Duck weed is making a comeback.

Soon the frogs will be coming to the pond in droves, hopefully the pond isn't now a pool of death for them.

Not sure where to go next if this situation doesn't improve.

The pond does look nice!!