Pond Boss Forums MANAGING AN EXISTING POND Fertilization How much clarity is needed before fertilizing

I have a pond that tends to be very turbid in the fall and winter months (2 or 3 inches of visibility). The reading I have done suggests that this level of turbidity renders fertilization useless because you don't get adequate sunlight penetration to have the desired impact on the food chain. I diagnosed the problem as clay turbidity and bottle testing showed that I could clear the pond with gypsum . This spring I attempted to clear the pond by adding 2 tons of powdered gypsum by hand. The pond is approximately 7.5 acre-feet (1.8 acres surface area). The gypsum did not work, at least immediately, however in the past three weeks or so the pond has cleared to approximately 1 ft of visibility. The pond immediately downstream has about 16-18" of visibility and I attribute this to our best water feeds this pond. Our pond overflows to the next one when it rains. Both ponds have similar bottoms, pH, alkalinity, hardness, and the watersheds look practically the same in terms of vegetative cover. I am afraid of alum as I worry about dropping the pH too much. The pond pH is approx 6.8 and alkalinity is only 30-40 ppm.

The pond was stocked with 200 channels - 8 to 11", 200 bass - 8 to 10", and 1000 coppernose bluegill - 3 to 5" last July. There was a preexisiting population of green sunfish of all sizes and a handful of channel cats. In spring, summer and fall I feed with high protein pellets - probably 15 lbs per week. Some of my neighbors feed as well although not as consistently.The bass we stocked were feed trained and they are growing but not as fast as the channel cats. Some of the channels have almost doubled in weight. Visually, I see quite a few small panfish since the water has cleared- 1 to 3" in size. I also put in 25 lbs of 4-6" tilapia about 6 weeks ago to add to the forage base.

My question is this, is 12" of clarity enough to fertilize the pond or do I need to try to get more clarity before fertilizing? I'm a newbie at trying to manage a pond so any and all advice is greatly appreciated. Adding gypsum was fairly expensive, time consuming, and was a lot of work as I simply shoveled gypsum into my trolling motor propwash, one shovel full at a time and I tried to distribute it as evenly as possible. I'll add more gypsum if I need to but hoping not to have to.

Our long term goal is to get a good mix of all sizes of bass, bluegill, and channels and be able to do some harvesting of each. I realize the cats might not breed without addition of the right kind of habitat (I put in 20 or so cinder blocks but I think that won't be enough by itself). We want to get the bass/bluegill populations breeding and self sustaining to some degree. I have every reason to think the bluegill (and greenies) are breeding and providing a reasonable forage base. Not sure if the bass are breeding or not.

Welcome to the forum!

Hang tight, I am sure someone with better knowledge in this area than I will be along shortly to give you a good answer...

I think that level of alkilinity should support fertilization. Magnolia gets quite a bit of rain with resulting runoff. Can you control sediment/clay from being washed into the pond?

The cats will probably reproduce but the offspring will most likely be eaten. They are pretty slow swimmers and very succeptible to predation. Generally, CC is a put and take fish.

I can almost guarantee that the bass are reproducing.

Yes I would try it in fact, one method to help "clear" the pond is with fertilizer spread over suspended clay pond. Probably go on the high side of application that is 8 lbs/acre water soluble. Wtaer solubel much better chance of workign than granular or liquid. You might get it to 18 inches but it now be a combo of phyto and clay. The only way to know is send a sample (Bill Cody)or measure DO it will change throughtout the day quite a bit if phyto. But yes I agree with thought process on waiting but now worth trying.

Dave, yes we do get an average of 50" of rain a year and it has been a wet spring. The last few big rains have not really caused problems though. I have noticed much of the runoff into the pond has been clearer than the average pond water. I am encouraging all of the homeowners to plant grass on their banks and most have done so.

Thanks for the answers folks.

Just to update on what happened and what I did.

I got some better test gear, a pool test kit instead of just test strips. It turns out that the test strips aren't very accurate. My pH fluctuates from 8.0 in the afternoon to 7.6 or so in the morning versus a costant 6.8 reading with the test strips. My alkilinity is 25 ppm rather than 30-40 ppm measured on test strips and total hardness is only about 60 ppm vs 100+ measured with test srtips. I believe the titrations much more than the strip readings.

As the water in my pond warmed this weekend , I got up to 22 inches of visibility on a Secchi disk which I felt like was plenty to proceed with fertilizing. I am guessing the combination of the gypsum I added to the pond and phytpplankton activity are the reason the visibility has increased so much in the past week or two.

I also removed an estimated 10 lbs of filamentous algae from the pond surface with a pool skimmer before I feertilized. The FA was not out of control but I felt like it was better to be proactive than have a big problem post fertilization.

I fertilized this afternoon with a gallon of 10-34-0 inorganic liquid fertilizer. I diluted the gallon of fertilizer with 15 gals of pond water and distributed it over the approx 1.8 acres surface area of the pond in my trolling motor propwash. The fertilizer called for a gallon of fertilizer per surface acre but I want to go slow and see what happens. I feel like you can't undo it once you fertilize so am taking baby steps. I'm shooting for 15-18 inches of post fertilization visibility.I'll let you know how it turns out.

I'm planning to add a few tons of limestone to the pond between now and next spring. I want to try to get my alkilinity up above 30 to feel more comfortable that ph swings won't be an issue.

Going slow until you have experience with a particular pond is a wise choice. Here is the archive on fertilizing.

http://www.pondboss.com/forums/ubbthreads.php?ubb=showflat&Number=96127#Post96127

Thanks very much ewest for the information and sharing.

I have 18" of visibility as we speak which is right about where I wanted to be. The water has what I imagined as the perfect pea greenish tint. I don't plan to fertilize again for at least a few weeks and won't even do that if the visibility stays near the 18" mark.

Should I expect the water to get muddy again in the fall/winter now that I have addressed the clay turbidity problem? My guess is muddy runoff will undo what I have done over time and I'll have to resume measures to address the suspended clay. I'm hoping it won't take such a big amount to keep the visibility up going forward. A good bit of the gypsum I added is laying on the bottom helping me, right?