1) Brown algea is probably diatoms. The silicone from decor/tank in a newly cycled tank is the nutrient culprit. Add 4 nerite snails or otos take get things cleaned.
2) Tap water is depending on where you live. I would get it analyzed for nitrates (chloramines) and Cu or other heavy metals. Alkanity and hardness are also critical for continued plant growth.
3) I would keep up with the weekly water changes, but follow directions as indicated. Circulation and a NPK nutrient rich substrate are also important. I inject my Flourish into the substrate and water my terrestial plants with my tank water.
4) I noticed the red plants look like the emersed form of ludwigia glandulosa, so those leaves might melt off in preparation for the submerged kind. Initially low photoperiod (8hrs) might benefit your plants' acclimation, but bump it to 10-12hrs once you notice new growth. Those lights should not be a problem but some other members might pounce on the actinic for freshwater tanks, i,e algea growth, human skin cancer, etc
Last edited by AirstoND; 11-28-2012 at 12:58 AM.