Pond Boss Forums INTRO Questions & Observations Fish Kill

Lost 4 20-22" Bass last Thursday, which I am still sick about… Checked things out Friday morning (7/19/13), hoping whatever had happened was over and I noticed 12" Bass and BG were in big groups at the edge of the pond. As the day went on they receded into deeper water.

I had been running a 3 disc bottom diffuser aerator 24/7 since spring that was built based on feedback from this forum last summer; it’s using the economy ECO7 pump.

Since I assumed the issue was lack of DO, I didn't yet have a DO meter. I added a 1/2HP HO Kasco deicer I mounted to 3 t-posts in the pond to add surface aeration. The deicer created a plume of water 16” high and about 30” wide which I was hoping was adding a substantial amount of DO.

I just purchased the home last year and don't have any history on the pond. It was heavily infested with Coontail but also some great bass! The coontail was so thick it was just about impossible to fish by mid June. So we decided to treat the coontail with Reward. I treated 50% of the pond at a time, the first half of the pond was treated on 6/7/13 and the second half on 6/28/13. Within days of both treatments the Coontail seemed to die off and drop below the surface of the pond. Everything was looking great until last week!

I was hoping my 3 weeks between applications would be more than sufficient, along with bottom aeration that had been running all season… I had zero fatalities until 7/18/13.

Not wanting to experience this again and play the guessing game I purchased a DO meter this weekend. I took my first reading last night and posted the results below. The reading last night seemed good from what I have read on this forum. But I was shocked when I took my readings at 6am this morning. From what I have read they should not be below 3ppm. I didn’t see fish gasping like a few days ago.

Based on these readings does it appear the aerators aren’t adding enough DO to the pond? Any other thoughts or suggestions would be greatly appreciated.

1.5 Acre pond, 8’ max depth.

DO Reading MW600 Meter
7/21 6PM Near Dam 8' Deep
12” 16.5
24” 8.5
60” 3.7
72” 3.1

Middle of pond - 7' deep
12” 12.3
24” 7.5
60” 1.2

Near surface aerator - 5' deep
12” 7.0
24” 5.9
60” .3

7/22 6AM Middle of pond - 7' deep
12” 1.1
24” .8

Near surface aerator - 5' deep
12” 1.1
24 .9

Are those readings from 6AM as you stated in the paragraph or 6PM?
You would expect your DO readings to be their lowest early in the morning since plants consume oxygen at night. It appears that your aeration system is not adequate. Your pond is still stratified and some of those surface readings are horrible!! You should talk to Ted Lea about that compressor you are using. He was doing some flow measurements on that compressor at the Indiana Pond Boss get together and the CFM under pressure is very low.

I think top 3 are PM bottom 2 are AM..

What is the water temperature? If really warm, even aeration wont help much if oxygen cannot dissolve. It is certainly better than nothing.

I would suspect you have a lot of decaying matter in the bottom using up the O2 faster than you can get it to dissolve in under warm water conditions. Any chance of shading the water during the day to keep it cooler?

Oh, I see ~ three readings from 6PM and 2 from 6AM ~ definitely inadequate aeration. Warmer water temperatures do hold less water, but if properly sized, a bottom diffused aeration system would show higher DO levels. At 95 degrees, water can hold 6.95 PPM dissolved oxygen. I still recommend talking to Ted ~ if you want to stick with a "do it yourself" system, he'll be able to help you out. Highflyer actually shot some video of him this weekend at our Pond Boss gathering in Indiana about this exact subject. Hopefully it will be posted soon.

Was the meter calibrated and were the readings adjusted for salinity & altitude and was the meter "at rest" before the readings were taken? (Just wanted to be sure) You can't just turn it on and start taking readings as you probably know.

Are you running both systems 24/7 or only part of the day? What were the water temps when you took the readings?

I see the size of the pond, and the max depth. Where are the diffusers placed, and how many are there?

edit: I see you're running 3 diffusers. Are they grouped together or spread out? What size is the air supply line?

I think once you see the numbers that Ted has, you'll be suprised.

Correct the top 3 measurements are from 6 PM last night and the bottom 2 are from 6 AM this morning. I did not take a temperature reading but I would guess the surface has to be in the mid 80's. I'll get a temperature reading tonight. High temp for us today will be 97.

I was shocked that the 1/2HP surface aerator doesn't seem to be making much of an improvement to the situation. I would think at least the water near the aerator would show an acceptable level of DO. As soon as I powered on the surface aerator I noticed the water felt cooler around the surface aerator. I assume its pulling enough water from depth to the surface to mix with the warmer surface water.

Not sure how I would shade the pond, and during the day when the pond gets sunlight it seems to have a positive impact on the DO.

I too am concerned with the decaying plant matter. If I was to treat the pond again I guess I would only do around 25% at a time, but even at that rate I would be concerned something like this could happen again. I am surprised that it took almost a month after my second application of Reward to have any issues. I would have thought something like this would have occurred closer to application time and hopefully before a got to the second application.

Would adding another 1 HP of surface aeration be recommended? Is there a formula to calculate how much aeration is needed, something like X hp per acre for an additional X ppm of DO?

Are you running both systems 24/7 or only part of the day?

esshup: The diffusers are grouped together. The air supply line is 3/4 Pex, the diffusers are in about 6' of water. The diffusers are from Environmental dynamics and are 9" FlexAir Threaded Disc Diffusers

The 1/2 HP surface aerator is in about 4' of water and suspended about 12" below the surface. Its creating a nice plum of water but unfortunately it doesn't look like my reading are good.

The meter is new, it is a MW600. I calibrated and zeroed the meter using the open air method as the manual instructed. I was getting a reading out of the water of 8.2 and did allow the meter to settle down before taking a reading. When taking readings from the pond I placed the meter at the various depths and then waited about 15 seconds for the reading to stabilize.

Both systems are running 24/7. The surface aerator was just added last Friday.

I don't know the exact size of your pond, but going from the info that you have posted I think that a Kasco agitator in the 8400AF size range would fit your needs for times like this with your current bottom aeration diffuser system. I agree with Sue, what you have now is undersized for your pond. That's one of the downfalls of doing a DIY aeration system. Yes, they are cheaper, but you don't know if the system that you are putting together for your pond is adequate unless you do a LOT of calculating and research.

That's why the system packages are more expensive. There is a LOT of testing and design that goes into them before they ever hit the market, and those costs have to be recouped somehow or else the company won't be around very long.

CFM compresor output at various depths
Bubble size generated by the diffusers
How much water each diffuser will lift
Placement of the diffusers in relationship to each other determine how much they will lift. 3 diffusers placed a certain distance apart will lift more water than those 3 placed individually. How far? For a DIY guy, you have to have equipment to measure water flow to figure it out - buying a system it's already figured out.
Cabinet size
Cabinet cooling requirements
etc., etc., etc.

I would agree with sue and esshup. The DYI station you have which has been widely known as the RC51 system has not been tested on anything really over 1 acre. Your depth is good but size of pond is a bit larger. Plus with it being so shallow its hard to mix all that water out of 1 eight foot air station. I don't know if that would have worked even with a different system??? If that were me I would have had 2 stations running not just one. Couple that with killing off all your vegatation and it couldn't quite keep up.

Sounds like you got it back under control now though.

RC

Could you please provide the depth profile of your pond in correspondence to the above readings? It appears that you have supersaturated oxygen conditions near the dam in 12 inches of water. This indicates either a very high phytoplankton count or aquatic plants in that area. I suspect the former condition rather than the latter..

Also, FWIW....for coontail control....I personally like Aquathol K over Reward for several reasons. Aquathol K provides a "slower kill" (reduces chances of oxygen crash) in addition to being fully biodegradable (Diquat is not). Also....check out what Diquat based herbicides do to your pond "friends" Daphnia hyalina at normal use rates... ..

Remember....some level of native aquatic plants such as coontail (Ceratophyllum spl) are beneficial for your pond.....

Jeff - I edited the post to provide the approx depth at the locations I took the DO readings. The pond is fairly rectangular with an island in the middle. I just recalculated the surface area and it is approx 1.25 acres.

Charlie:

Look at the specs for you diffusers. I don't know which ones you used, the ones that are rated at 0.5-4.5 SCFM or the ones at 1.0-8.0 SCFM each. But keep an eye on the Who's up for a road trip to N. Central Indiana thread. Ted tested that same compressor on a diffuser at different depths in my pond and the results will be suprising - you too RC51!

Can you find a volume/pressure curve for that particular compressor? I looked for one and couldn't find one.

So what SCFM are these vertex fusers. I use the .5 to 4.5 SCFM not a vertex fuser though, and can push air out of all 3 at 8 to 9 feet? And your telling me you can't push air at 5 feet with the Eco 7 with a vertex fuser??? My air pushes so hard I can't keep my boat next to it. I am not trying to sell anything I simply made a DIY system and it works for me. And if someone else wants to know about it then I will tell them. I am going on 4 years now and still pushing air like mad. And in this heat here in arkansas it hasn't missed a beat and I have yet to have a fish kill. I don't know maybe I am just lucky??? Charles situation has a whole lot of it all depends in it though.



RC

Oh and one other thing. I don't care what type of fusers you have if this pump only put out 2 psi there is no way I could run it at 8 and 9 feet??? There are a few guys out here running them at 10 feet? So whats up with that?? I'm just saying...

RC

Charlie and RC51,

We tested the ECO 7 and the best pressure we could get was just over 2PSIG. The pump could not push any air to 10 feet, and at 3 feet it was pushing just under 2 PSIG which showed less than one SCFM on a testing gauge. So the pump we had to test could push some air to four feet, but the lifting action would be severely limited.

Look for the pictures on Scott's thread.

Well then you had to have a bad pump. Once again how am I pushing air at 8 feet then no problems? If the Eco 7 only put out 2 psi I would not be able to run mine at 8 or 9 feet and I am doing as I write this and so are others?? So how do you explain that?

RC

RC,

How many PSIG are you able to put out with your pump?

There could easily be some quality control problems where they make the Eco7 pumps. I have a small model of Eco Pump that now after a year is making a lot of noise and not making any air to push out air 14" deep in a RAS tank.

Ok, this has me stumped. Readings last night were the best I have seen and I took them a little later in the evening (9pm) but I still expected based on the other readings and my undersized bottom and surface aerator that I would once again have very low DO in the morning. But too my surprise the DO readings this morning seems to be as good as I would hope for based on what I have read here - please correct me if that's the wrong assumption. The readings for last night and this morning are below.

Is it possible that the aerators have finally caught up after running 24/7 for 5 days or is something else at work here? I hope this disaster is over.

It has got me thinking, if I had a properly sized surface aerator would I just run it at night for the entire summer to hopefully eliminate the chance of this happening again?

Seems like a DO probe that could be left in the water 24/7 and provide readings remotely would be a must have item? Does anyone make such a device. Even with my MW600 I don't think I would have noticed the problem until the biggest fish in the pond started floating.


Updated DO reading from 9pm 7/22 and 6am 7/23
Near Surface Aerator
9pm 6AM
12" 19.2 11.2
24" 19.0 10.4
60" 9.5 9.0
ST 84.5 82.0 - Surface temperature

Dam
9pm 6AM
12" 18.0 11.0
24" 17.7 10.5
60" 13.0 6.3
ST 84.3 82.5

Middle
9pm 6AM
12" 18.8 10.5
24" 18.2 10.3
60" 11.1 10.1

I appreciate all the feedback you guys have provided. I would be completely frustrated without you guys and this forum.

Thanks!

Charlie are the numbers PPM or %?

If PPM, your meter is not calibrated correctly because water at 84ish degrees can't hold that much O2, it is just not possible (laws of nature). If that is % then you still have a O2 problem.

About your questions. A surface aerator should be able to add enough O2 to prevent a fish kill. The 1/2 HP Kasco you have should be enough, but with the vegetation dieoff, no one really know, because we don't know how much dead material is in your pond.

Continue to run the surface aerator 24/7 it is the best way to add O2 to the water.

Okay here is the Eco 7 video we shot on Saturday.

The reading from the MW600 DO Meter is mg/L. Is there a straight forward conversion for PPM?

mg/l and ppm are the same.

Saturation is percent saturation. Most meters have an option where you can go back and forth from mg/l to % saturation. Saturation actually makes more sense.

When you first turn on your D.O. meter do you wait for the reading to stabilize? My YSI 550A has an option to calibrate by putting in saturation mode, waiting for the reading to stablize, and then calibrating it according to directions. You should calibrate before every reading. Another way to calibarate is to use a chemical test to measure mg/l and calibrate your meter to that reading.

Also moving the probe back and forth through the water is important to get an accurate reading.