Green water fallacies?

I've got another question for you all. Someone on the Goldfish List has
stated firmly that green water is caused by incomplete biological
filtration, that if our filters were working, there would never be green
water. His reasoning is that green water algae can only live when there is
ammonia around whereas "hairy algae" (his term not mine) can thrive on
nitrates and phosphates. He claims this is why green water is *never* found
in planted tanks.

Neither his conclusion nor his assumptions along the way sound right to me.
Advice? TIA.

Greg. Tong
San Francisco, CA, USA
gtong at sirius_com

"Every infinity is composed of only two halves."