Mister Gardener and Altum,

Must be my water - comes out of the tap with nitrAtes between 10 and
20ppm depending on the time of year. Any direct sunlite at all = green
water. Funny though, lights are on a timer and at peak light, I'm
putting 4 watts per gal. in the tank (4 hours). Late afternoon sunlite
would hit the tank if the drapes were open - every once in a great
while one of us will forget and leave them open - by the next morning
we have the start of an algae bloom. Hmmm - mabe it's just that little
bit of extra light that does it (?)
................... Frank