Pond Boss Forums INTRO Questions & Observations Brown Surface Algae?

Ryan - do you feed the trout pellets when the water is cooler? Feeding fish adds nutriets to the water body depending how much is fed /ac per day. A higher phosphorus and lower nitrogen in the water could cause a bluegreen algae surface scum bloom as mentioned by M.Paris. If you use a copper product to reduce it, I would just spray the scum part and not treat the whole pond with copper. Trout and minnows are very sensitive to copper compared to bass and sunfish. Get some suggested dosages of Cu to water ratio here before doing a copper treatment. Note that killing all that algae biomass and allowing it to sink and while sinking and sunk, it will consume lots of DO in the deeper water stressing the trout. It would be best to try and skim out using a very fine mesh net or pump out the thicker surface scums to mimimize DO consumption.

I've been trying to think of an easy way for you to check if it is bluegreen algae without looking at it with a microscope. Try this: collect some of the surface scum with water in a glass jar about 1/3 to 1/2 full. Cap the jar for 8-12 hours in open light not darkness. Open the lid and carefully smell the air in the jar. If the air smells very moldy or a strong vile odor then it is very likely bluegreen algae. Note: some bluegreens will not have an offensive odor.