I was at a buddies house today. He has a 1/4 AC pond that is about 8’ deep. He runs an aerator and fountain all the time. At least it seems like they are in all the time. I noticed his pond had a lot of algae floating on top. I’ll try to post a pic or two. He says he really fights it. My non-aerated pond 90 miles north has some algae a few weeks ago, but is clean now. Is it possible the full time aeration and fountain are putting too much oxygen in the water, and that contributes to the algae? Just curious. I’d like to help him if I could.
As Fishinrod says bottom aeration usually keeps DO on the bottom and can increase decomposition of organic materials that release nutrients that could help stimulate more plant growth. Canada geese are flying toilets that produce lots of manure. OSU did a research study that showed 10 geese make the equivalent manure of 1 cow. One cow pooping in a 1/4 acre pond is a LOT of organic fertilizer. I am pretty sure that algae likes organic fertilizer.
Question was - "Are there certain pond circumstances where adding aeration can clear the algal blooms?" It all depends. There probably are certain pond situations with certain types of algae were aeration either surface and/or bottom could cause an algae bloom to subside. When this happened the naive observer can wrongly conclude that aeration is a cure for too much algae. I have seen this happen with people who think ALL algae is the same. NOT! What was not known by the casual observer is there are many, many DIFFERENT species of algae, literally many thousands, with each type usually requiring different conditions to produce a good amount of growth or bloom. This is just one of the things that makes them different. For one example, I am sure that there are some algae that does not like moving water whereas some algae like moving water. Some algae species like cool or cold water as a narrow temp range (stenotherms) and some that like warm water or a range of temperatures (eurytherm). Most problematic algae grow best during warm water conditions.
Aeration does change the conditions and chemistry of the water. That is a fact. If the new conditions are unfavorable for the current algae, it will decrease in density. Whereas the new chemistry conditions will very likely favor another specie of algae. I always tell pond owners. No matter what you do to the pond, nature in its vast wide diversity of species will have something sooner or later that will grow in about every pond,,,, probably every pond. There are algae that grow in the snow fields of the Artic and algae that grows in the hot springs of Arkansas. Each has different growth requirements. The main stimuli of algae growth are nitrogen and phosphorus. It is very hard to eliminate those from a pond habitat. The nutrient concentrations in the water and on the bottom are constantly in a state of changing. The end nutrient chemicals of decomposition of organic materials are nitrogen and phosphorus plus all the macro and micro nutrients. Decomposition of organic stuff in the pond occurs all the time releasing nutrients. It is just slower in water with lower temperatures.
