when you said you cleaned your tank, do you mean a big water change? this would drop nitrates and phosphates (hair algea food) in your tank. RO has no phosphates in it so you should use that. less light will help a buch. i wouldn't cut it in half suddenly though. 8 hours might be the magic number, but slowly decline your lighting time until it makes a difference. maybe have actinics on for 12 and have full light on for maybe 11. if that doesn't work lower it to 10 etc.