Actually you are absolutely correct about the green spot algae ( BSA ) propagating when there is a low PO4.
The tap water I have and have tested many times shows 0.0 PO4 and a Ph of 7.8 and a Kh of less than 1.0
My tank has show a PO4 count of 2.0 before adding SeaChem's Phosguard and now the water shows 0.5 ppm PO4
I suppose I made the decision that BSA is a more acceptable algae than black beard algae or cladophora or blue green algae. And I seem to have a bit of BSA in the tank - but not really on the plants as much as on the back glass, the rock, or the driftwood.
Am I to understand some algae is considered a marker of a good, healthy tank?
If so - I have decided I would accept the type of algae that does little damage to the fauna of the fish. And prevent the more damaging algae altogether.
What do you guys think?
Buy the way the vals are now 12" long in just 2 days... I suppose they are happy plants
If you like I can provide another photo of the vals to show the grand progress I have been able to make. I will definitely post again within a few weeks.
Believe it or not I have clipped the cambia 4 times in month and propagated the other plants from just two of them.
And for those out there that want an excellent resource from planted tanks take a look at Rex's planted aquarium site. This guy is a mad man genius character. I like his tell it like it is style and he seems dead on with his advice. http://www.rexgrigg.com/Algae1.html