help with an algae issue..

[dclegern]

A 3 year old tank, consistently kept up.
1st year I dealt with a brown slime along the substrate. (now under control)
2nd year I dealt with red Cyano along the substrate. (off and on, but under control)
Now 3rd year............. Green hair algae. (NOT under control)
Water parameters are almost too good, everything is happy and healthy.
Just Green algae popping up everywhere.

I've got a 75 gal. drilled, rolling into a 20 gallon sump, Mag 9.5 return.
Sump is 1/3 loaded with tonga rubble-1/3 skimmer section-1/3 filters and return.
4 strip t-5 lights w/ all new bulbs that only runs for 6-8 hours per day.
6 small fish, w/ plenty of clean up crew. and all softies.
water stays at 77*-78* all the time.

I got off RO water for a while, but back on it.
Just getting frustrated with the whole algae issue on an otherwise beautiful tank.