disclaimer: noob grower, do not listen to below post:

light will get through that blue res wall. paint it black, then coat it 4 more times, then wrap it in black duct tape.

also clean and bleach the hell out of it.

i'd go buy your res worth of RO or Distilled water from the store too, it could be bad tap water.

Then for a few days it might be a good idea to add some H2O2 for a few days.

--edit, i just bumped an old unanswered post, oops.

sorry
macro Reviewed by macro on . DWC Stealth Hydro - Nute Solution - brown foam / ph rises +1 Hello, my setup is: 4 gallon Stealth Hydro DWC 2 85 watt compact fluorescents (flowering and grow) Stealth Hydro Grow and Flower Nutes GH Flora Shield After about 2 weeks, my first change of nutrient solution, plants looked great and grew very fast. However, after the nutrient solution change, problems have started. I set the PH at about 5.5-6, every evening its back to 7-7.5, the solution started to foam and a brown residue formed, inside the tank its a mess - brown foam and residue, Rating: 5