You may want to try our ...

You may want to try our ultrasonic biofilm control system for this application made by Hydro BioScience®,  From the tank description, our Mezzo-DB® unit would suffice.  Midge eggs are deposited in the biofilm layer where they grow to larva, then pupa before emerging as a fly. Eliminating the biofilm layer stops the process at the root cause.  The ultrasonic signature of our device is interpreted by anaerobic bacteria as water turbulence, a place they are naturally adverse to colonizing.  This prevents the first layer from forming so that subsequent aerobic bacterial layers do not continue to attach.  Device cost is under $2000.  george@algaecontrol.us