Pond Boss Forums MANAGING AN EXISTING POND Fertilization phytoplankton, zooplankton is there a TEST?

I have a pond that has been extremely out of balance for many years, no LMB ever removed. I have been removing as many LMB as I can for the last year. The relative weights for the LMB are still in the 75% range. They are no longer easy to catch.

I was concerned about how few CNBG I saw that were <3" last August. This Aug. nothing has seemed to have changed. From what I can observe along the shore & throwing feed I would hazzard to guess that the small are in the 10% or less range, Medium 40%, Large 40%, XL 10%.

Answer to my BG in a balanced pond:
Originally Posted by Bill Cody
I will provide my opinion of an answer as a best guess. First I will define sizes for the categories of small 1"-3", medium3.1"-5.9" and large 6"-9". Plus I will add extra large 9.1"-10" to the size groupings.
small 1.0" to 3.0" = 70%
medium 3.1" to 5.9" = 20%
large 6.0 " to 8.0" = 9%
X-large 8.1" to 10.0" =1%

Is there enough food for the fry & fingerlings?

Although my visibility is 24" it is not a green color, a brown but not muddy brown & changes little throughout the year. I now wonder if it is from something other than phytoplankton & zooplankton? Wondering do I need to fertilize? Is the 24" visibility from stain in the water? It does not appear to be solid particles that settle. Is there a simple test to evaluate for phytoplankton, zooplankton and their abundance? It is a retention pond. Phosphorus is high in the soil, Water Ph is 6.7.

Suggestions welcomed!

A jar test is always easy to perform.

Here is a link to a discussion.

Pond Boss Thread - including jar test

That will help determine if you have suspended silt, charged clay particles in suspense, or an organic bloom.

I don't know if phytoplankton die out in X days and zooplankton die out in X + Y days for the jar in the dark? The zooplankton might just die out due to short life spans or lack of phytoplankton to consume, but presumably they might be second to die?



A pond that is murky due to suspended sediment is certainly preventing sunlight from reaching the organisms in the water column that make up the critical base of the food chain.

Since you are in Florida, do you have enough run off days due to frequent rains such that your inflow water is muddy? If not, then are there creatures in your pond that keep the sediment stirred up? (Such as carp/koi, bullheads, some other types of trash fish?)

Finally, if it is charged clay particles, then those can stay suspended a LONG time. Read some of the alum threads.



The other option is that you have already achieved the population changes that will start improving your pond. Your current fish have all grown up under stunting conditions with some gaping holes in their food supply. Time may be your most important missing ingredient at this point. I suspect your pond is already headed towards a better balance, just very slowly.

However, I am not an expert on that topic, but we do have some experts on the forum. Have you tried any fish traps to sample your forage populations? That might give you a different answer than your feeding observations? If you collect and post that info, you might get some wise advice.

Do you have any decent spawning areas for your CNBG? They are prolific. Perhaps if you gave them a little help, you could jumpstart your forage production?

Good luck on turning your old pond back into a champ!

J.E.Craig, before you think about fertilizing, you have to test for alkalinity. I prefer to have an alkalinity reading of at least 40, below 20 the plants/phytoplankton can't utilize the nutrients in the fertilizer.

What kind of fish cover do you have in the pond? If there isn't dense cover in 4' or less of water for the small fish to hide in, they will get picked off quickly. I'm talking about 10" of the pond surface area in that type of cover. Dense means open areas in the cover that are 3"-6", not open areas that are 12"-18"

I am working on that cover around the pond. The small areas that I have improved, have a greatly impoved number a mosquito minnows with small BG at the edge looking for a meal.

I did the jar test (thank you FishinRod). I was shocked how clear (very clear) the pond water was when I put it in the jars which made me re-check the visibilty in the pond, it was >36". Checked again 2 weeks later back to 24"

I used 3 jars, the first in the dark, became very clear. The second in filtered light appeared to have more green in it but not very much. The last I added 1/64 teaspoon of inside granular plant fertilizer & it had about 4 times? the phytoplankton that other jar in light had. Perhaps the brown I see is just a backround color from the pond bottom? I saw no suspended clay or dirt particles. I read :
https://americansportfish.com/fertile-ponds-and-plankton-blooms/

It seems like Voodoo. What is enough & when is it to much? How do you get that green turning to brown-green without overdoing it, yet keep it going throughout the summer? Trial & error? I have never seen that green bean color. I have never reallly observed a great deal of change in the pond color through out the year. When there is a long stretch of very little rain, I have noticed that the visibilty improves but never thought to measure the amount. I would like to know why the visibility improves?

If you have visibility of 24" then you do not need to add any fertilizer. The danger to adding more fertilizer with that amount of clarity is that you can very easily over-do it and have too big (dense) of a phytoplankton bloom, which will create a fish kill at night if you don't have an aeration system in place.

Adding fertilizer will turn a brown bloom green, but at the same time if you add too much then the green can get too dense. If you start feeding the fish that will help you in two ways. 1) it will feed the fish directly. 2) the excess nutrients that pass through the fish will feed the phytoplankton in the pond which will increase the fertilizer in the water, feeding the "bloom". The "bloom" only feeds the smaller fish (swim up fry and fingerlings) while the feed (depending on the size of the pellets) can feed fish from fingerling size to adult size.

If too much fertilizer (i.e. nutrients) is added via "fertilizer" or indirectly via fish food, you will have too dense of a bloom and the only way to mitigate (remove or lock up and make unusable) is to do a nutrient abatement procedure via Alum or another product that ties up "P".

When I first found Pond Boss, I thought, "This is awesome. All I have to do is follow all of the expert advice, set up my pond and fish stocking the right way, and I am good to go for many years!"

Now that I have been learning for many years, I finally realized it is always like the guy at the circus spinning all of the plates on the sticks. The pond is ALWAYS in a state of balance that can be knocked off course from several different vectors.

Even the experts on the forum have had fish kills, plants get out of control, dam breaches, etc.

The best you can do is keep adding to your knowledge base, and keep closely monitoring your pond. That way you will be wise enough to see when a plate is starting to wobble and getting close to falling - and you can fix the problem long before it is a crisis.

I think with a good healthy pond you are sometimes going to have blooms and visibility lower than you would like. Just think of that situation as you taking good care of the bottom of your food chain. I know we like to focus on the TOP of the food chain, but that can only stay healthy by caring for the bottom.

Well said Rod.

A couple of truisms.

First; it’s all about balanced water.

Ponds are sorta like gardens. No matter how expensive the seeds, you have to have proper soil to have a healthy home for fish. If it’s weak, add fertilizer. But, overdo it and you can kill everything. My zeal has not always been in my best interest. I once fertilized both of my ponds. They are about a mile apart. In a drought, I had a fish kill in the small (1/4) acre one but not in the big, about 2+ acres, one.


Next, there are regional differences. It rains in East Texas but not so much in West Texas.

Topography? Yep. I have a neighbor about 1/2 mile from my place. He has a weather station that I check on the internet for rainfall amounts. I get about 2/3 to 3/4 of that amount in my rain gauge due to my place being about 25 ft higher elevation than his. The clouds split when they get to my place. Another neighbors front gate is about 50 yards from mine. He is also downhill and gets more rain than I do even though our gauges aren’t over 250 yards apart. My 2 rain gauges, about a mile apart, never agree.

I sometimes remember what the Prime Minister of Egypt, Golda Meir, said. Her ancestor, Moses, roamed all over the place and settled down where it didn’t rain. I understand and can relate to that.

See this thread for pics and info - Bill's plankton pics and analysis.

https://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=321151&page=1