Pond Boss
Moved to a new house 3 years ago with a 3 acre pond in the back. Max depth = 15 feet. Location is north texas. The pond shares land with a cattle ranch, and the cow manure gets into the pond and wreaks havoc.

Anyways, the 2 main nuisance plants in my pond are coontail and filamentous algae.

Here's a typical seasonal pattern:

Early March: completely clear
April: surface plants emerge (no algae or coontail yet), I don't mess with the surface plants and just let them be
May: small amounts of filamentous algae bloom
Mid June: Coontail emerges
Late June/July: huge amounts of filamentous algae and thick coontail -- can cover 80 to 90% of pond
Late August: filamentous algae starts to recede
September: coontail starts to recede

First I put in 2 aerators. Made absolutely no difference to the above pattern.

Next, I started using Mizzen copper algaecide. At first I diluted it according to instructions and used a spray to spray over the surface. It didn't work very well, at best may got rid of 10% of the algae/coontail

After that I tried using undiluted Mizzen with the sprayer. Again, no more than 10% improvement.

Finally, I nuked the pond. I bought 8 gallons of Mizzen and instead of diluting or spraying, I just used a pitcher and started dumping undiluated Mizzen straight into the pond in a concentric pattern around the boat I was using.

This finally worked. It got rid of 90% of the algae/coontail. I had to reapply it in the same amount on 5 separate occassions during the summer. So a total of 40 gallons was used in 1 summer.

The Mizzen instructions say that 4 gallons should cover 2 acres, or 5 gals for 3 acres. But when I tried that I got no results.

I also experimented with the timing of the application. The first year I didnt apply anything until the algae/coontail was visible from the other shore.

The next year I applied it in March before the major growth started. This helped curb the algae but for coontail it turns out that pre-treating the area before coontail emerges seems mostly worthless to me. The coontail was always massive in June/July even if I treated the pond 2X before coontail even emerged.

Another thing I noticed was that the time of day I applied the chemicals was critical. If I waited until evening to use the chemicals, it really didnt work. Also if I put the chemicals in and there was a sudden rain storm or overcast afterwards, the chemicals didn't work very well. I found out that you really need to put it in the morning at full sun exposure and hope that it stays sunny the whole day so that the algaecide will work its way into the algae/coontail. Otherwise you just wasted your money.

Anyways, just my experience.

I hate to use so much chemicals, but I am careful to treat only 1/4 of the pond at one time. I've never had a fish kill despite the huge volume of chemicals used.
Sounds like you're creating a copper mine. I hope you don't have long term plans for your pond? Keep up that rate of treatment, you'll never have a diatom, phytoplankton or zooplankton.

I have issues with Filamentous algae along the shorelines and 3 times a year I physically remove it and take it 200 yards away to the garden. I see a 10-15% reduction annually. I am sure I'll hit the law of diminishing returns relatively soon.

You may want to look into, sodium carbonate peroxyhydrate (SCP) and limiting phosphorous, which is ridiculously difficult. The USGA has developed some filtration for wastewater but I have never looked into consumer uses. SCP requires higher levels for coontail but is highly effective against algae and has less long term effects.

I have never used and have only casually researched it. Curious if anyone has?

https://pubmed.ncbi.nlm.nih.gov/27322608/

https://dnr.wi.gov/lakes/plants/factsheets/SodiumCarbonatePeroxyhdrateFactsheet.pdf
Would Tilapia and Grass Carp be an option?
Originally Posted by Steve_
Would Tilapia and Grass Carp be an option?


Yes, but he would need to get a permit from TP&W for the TGC.
I forgot to mention that I did use tilapia and carp already. I put in 20 carp and 150 lb of tilapia. Neither one made a difference.

Maybe if I put in 100 carp and 1000 lb of tilapia instead it might work better. But the TPWD would only approve me for 20 carp.
Originally Posted by Joey Quarry
I have issues with Filamentous algae along the shorelines and 3 times a year I physically remove it and take it 200 yards away to the garden. I see a 10-15% reduction annually. I am sure I'll hit the law of diminishing returns relatively soon.

I tried that approach too.

I spent 50 hours digging out tons of algae and dumping it. Within 2 weeks, the algae came back like I had done nothing.
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