Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations fish kill

So it appears i have lost several (100?)fish over the last few nights.

History. bought pond 5 years ago - bad shape lots covered in duckweed full of muck. used fluridone. put in a two station aerator. stocked pond march of 2015. fish population this year good. fishing good. pond looks great no more chemicals since the fluridone on year one.

usually i get algae mats on the surface. had them this year in june but went away in early july for some reason.

i have the green water right now with some pond grass growing under water.

my aerators run in the daytime only because i wanted to same money and run only 12 hrs. i did no research at the time as to when to run the aerators.

i did some research and read that the alae may suck o2 out of water when sun goes down....do you think this is the case? did i screw up by running the aerator during day and not night?

pond is a bit low and there is not run-off from farmers...not enough rain for that.

thanks for any input!
Adam

I am not sure exactly what a few fish loss is, it just a few, then it may not be an issue. Dozens or hundreds, yes.

I believe I would run the system at night vs. the daytime. I don't see how it could hurt and may help.

Not an expert by any means, but from my researching of the actual experts, your plants will release O2 during the day and use it at night when photosynthesis is not going on.

I have lost more than a few. Maybe 100.

Plants create O2 during photosynthesis which obviously occurs during daylight hours. They respire during dark periods - this is when your DO levels get low, especially right before sunrise. Periodic aeration can work, but since DO levels are lowest during dark, that's when your pond benefits most from aeration. So, you got them switched around unfortunately. I don't know how much you're spending on electricity per month, but strongly consider aerating 24/7 when temps are over 60 as the fishery you've spent so much time and effort establishing and managing is certainly worth the investment.

Thanks for the info. I wish I would have done my research sooner.

Don't be too quick to blame it on aeration alone. You have a beautiful pond and from the picture above I will make a rough stab that it is just about an acre? If it is typical depth for a pond that size and gradual sloping banks down to depth then your amount of water may have easily completely turned over with 12 hours of aeration using 2 diffusers going at once (assuming good quality membranes on those diffusers making millions of bubbles and that the membranes are clean). If you completely turned your water over in 12 hours then it is unlikely that an O2 crash was to blame.

Perhaps a fish kill immediately after taking a stagnant pond and turning on the bubblers for the first time and running them to long can be blamed on the bubblers, but it sounds as if you had the pond cleared up and had aeration running for quite a while before this kill event.

Superheating can be a problem with daytime aeration running but you would have to get temps from your surface and at depth during the day while running aerators during day to see if that is a reasonable theory or not.

A vertex dealer on this forum can probably help you with the math to figure out gallons in your pond and gallons turned over by your particular compressor and brand diffuser disks.

Your pond looks great, think positive, I would try to nail down the details of volume, need for aeration, is 2 diffusers enough for 12 hour runs vs 24 hour runs and if you can get by with 12 hours then you can stop blaming yourself, you can run at night and save electricity and still feel good about everything.