Pond Boss Forums INTRO Questions & Observations Black Algae

Kay - Kellie is partially correct about the algae being Lyngbya however it could also be Oscillatoria the two are closely related (Blue-green, Cyanophyta) and quite resistant to chemicals. Both can form blackish spongy mats especially on mud bottoms (epipelic - growing on mud). This type of algae can frequently be seen on the bottom of mud puddles when the sediment has lost its oxygen. My experience w/ it in ponds is that it basically develops after the sediments have turned black underneath. Disrupt or rake your sediment where this stuff is growing is it blackish?
Mark is not correct about an aerator "burning" up nutrients. There is no scientific research that has proven that an aerator can do this ie physically dissipate, dissolve, burn, or blow off into the air nutrients. This is especially true for ammonia (nitrogen type nutrient NH4 & ions).. Ammonia can not be air stripped from the water UNLESS the pH is ABOVE 12. Numerous papers (authors) say you can blow off ammonia with aeration but this is a myth. If this was true fish haulers would not have any trouble with ammonia build up in their tanks. I've always suspected that heavy aeration can help bind soluable phosphorus (ortho-phosphorus) in the water column but I never seen any proof or scientific research that it works. BASICALLY, ONLY PLANTS ABSORB NUTRIENTS FROM THE WATER. To my knowledge there are no large economical nutrient vacuum cleaners for large ponds except water plants. Aquarium filtration techniques can strip some nutrients from the water on a small scale.
A good aerator that produces a STRONG boil may? help you get rid of your "black algae". A windmill aerator probably won't do much; too weak of a boil, low currents, little spread of the water. Dragging a rake (like a Lake Rake on a rope) or disrupting the bottom and sediments will probably do MORE to reduce the problem than anything else you can do. Nature usu. does it in lakes with strong wave action. An aerator will definately improve your water quality!