Pond Boss Forums GENERAL QUESTIONS Water chemistry Filamentous Algae and Hard Water

I have a 1/2 Acre pond in lower Michigan. 16,000 sq. ft. surface area, about 7 ft. average depth. When I purchased the property 4 years ago the pond was in very bad shape. Full of chara and about 2 ft. of muck. I have removed about 50 trees that were very close to the pond, killed all of the chara using Cutrine Plus Granular and added aeration.

I've been adding beneficial bacteria and the muck is down to about 1 ft. at the deepest point. I am having a very hard time keeping the filamentous algae under control. Here is what I have tried in the last month:

6/12 - 3 gal. Cutrine Plus liquid
6/26 - 3 more gal. Cutrine Plus liquid
7/3 - 200 lbs. Green Clean Pro
7/6 - 2.5 gal. Earthtec Algicide
7/9 - 2.5 gal. Earthtec Algicide

I also keep the water dark using black dye since the water looks green if I use blue dye. I think this is due to leaves that are decaying and adding a brown color to the blue dye.

I just read today that water hardness may be contributing to my problem. Just checked the water hardness and it's around 400 ppm!

Before I add any more chemicals, I would love to have any suggestions.

Algaecides are only 'band-aid' fixes. Until you eliminate the source of the problem, you will be using them over and over. Perform a Phosphorus test. I would be willing to bet that it is quite high. Any level >5 ppm will cause algae problems, especially filamentous (it thrives on Phosphorus). You may have to apply a phosphorus binder to reduce the phosphorus level and 'starve' the algae. You seem to have already eliminated the main source, which were the trees. Leaves are a prime source of Phosphorus.

43,560 aq. ft. in an acre 16,000 sq ft surface = .36 acre.

+1 with binding P. Adding bacteria won't help if there isn't O2 at the bottom of the pond so they can do their stuff. Is there a bottom aeration system in place?

This isn't for most people but I have stopped FA using two different methods. The first was used by an old time ponder before the use of chemicals. It worked many years before my fish kill. For 1 acre I used 6 Israeli carp (I don't think you can buy them now) 20 KOI, about 50 CC when fully grown, and 18 GC. This kept the pond FA free and submerged plants and cattails in check. The downside was the water was somewhat turbid but not bad.


The other thing that has worked this year in 105, 104 degree days while ponds all around me are covered with FA and black with dye is this. My pond has excessive amounts of plants but this didn't work completely last year while I was restocking my pond. Remembering one guy on the forum in the past that had a pond with loads of Golden Shiners in it and didn't have any FA. Last year I put in Golden Shiners, FH and Bluegills with no bass, and it has plenty of tadpoles that eat FA. FH and BG probably don't do much but I just wanted them. Without bass to really thin out the minnows, they have exploded in numbers. I don't have even a trace of FA so far this year. I walk the pond a half dozen times a day and wade it once a week and FA is non existent.

See this wrt FA.

http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=92633#Post92633

I have about 20 Koi also and they tear up the FA looking for food before it has a chance to float

Instar, I did a Phosphate test and it shows 0. Is this the same as a Phosphorus test, or do I need a different test kit?

esshup - you're right, the pond is only 1/3 acre. (I'm in the habit of using 1/2 acre chemical amounts.)

Yes I do have a bottom aeration system in place that runs 24/7.