Pond Boss Forums MANAGING AN EXISTING POND Fertilization To fert or not from anaylisis?

Forgive me for reposting this in the fertilization topic. Its also in the water chem topic, but thought I might reach some knowledgable people who just look at this topic. Thanks:


I'm hoping for help with a lake on our southern MO property that we manage for fishing. The lake is 11 acres with an avg depth of about 7ft. The deepest is 17ft. The water is very clear and we have dense growth of mostly milfoil with some coontail. The fish have been stunted because, according to the biologist, they can't find their prey in all of the vegetation. We want to get the vegetation under control and we're thinking about fertilizing to create cloudiness to inhibit photosynthesis, but wanted to get an analysis of our water chemistry first. Test was conducted at Univ of Missouri.

ph........8.25
hardness....57
Nitrate....(.074ppm)
phosphate..(.013ppm)
Calcium....(13.17ppm)
Magnesium..(5.87ppm)
Potassium..(.881ppm)
Sodium.....(.927ppm)
Zinc.......(.001ppm)
Copper.....(.002ppm)
cabonate...(0)
Bicarbonate.(121ppm)
Amonium....(.260ppm)

Can anybody give any recommendations for lime or fertilizer or anything else that might help? Thank you very much

From my chemical back ground you could get away with some Phosphates. Your Bicarbonate will buffer the PH keeping it around 7.5 after you add some phosphate. This is what I understand will generate your phytoplankton bloom.

Dropping the PH a bit with phosphates because they are low, will free up some calcium, Magnesium, and potassium. When the PH is higher than 7.5 these are present but mostly tied up with a strong electron bond.

If some one would chime in with the perfect pond water I could calculate the % of fert to bring you in to that perfect balance. It may not be that easy. These numbers may change or fluctuate over the course of the day. I know the PH will I have seen it.

Cheers Don.

Just found out that the total alkalynity is 123 ppm, if that makes a difference. Also DonoBBD by adding phosphates, does that mean fertilizer? Thanks again, Doug

Those are really good numbers Doug! Fertilizing could start a bloom, but a little goes a long way and can be very easily overdone. Contrary to what DonBBB says, I would steer clear of adding any phosphate as it may promote a Filamentous Algae bloom instead of Phytoplankton.


FWIW, grass carp often take about 3 years to make noticeable changes in the plant dynamics. Since you are coming up on your third year, next season may be different. Next year, I would also try to kill one-third of your largest grass carp and replace them with new, 12+" GC.