I say get rid of the biowheel, many people have complained that it raises Nitrates levels.
You can place your fish in the other tank with the strong lights, just DIY a way to set 'em on top of the other tank. Check Seachem's deNitrate and/or Purigen.
You shouldn't use tap water. If you can't afford a full RODI system, a RO only would be better than what you're using now. Also, check Phosguard, it will take care of phosphates released by your carbon media (all carbons release phosphates no matter what the manufacturer says) |