Algal growth questions

[Myka]

^ Yep...most likely from poor water quality.

[krschulz]

Tank is 5 months old with T5 lights, all water parameters have always been excellent (K,Mg,NH4,NO2,pH,KH,Ca) so I'm assuming flow problem. Thanks. I have checked my flow rate and it is adequate for the 90 gallon tank, maybe just have my 4 powerheads improperly aligned. Any hints. Do most people have them aimed toward the overflow (as I do), 3 low and 1 high beside the skimmer opposite to the incoming water? Sorry if unclear, just don't know how most are set up.