In my 10g I have 2 x 13watt 6500k CFL's and I dose 1.3-1.4ml of excel and 0.17-0.2ml of comprehensive daily. The daily dosing of the comprehensive add's up to the recommended weekly dose. I believe that dosing daily is better.
Anyway, I have GSA on most of my plants and on my glass. I was told that PO4 will stop the GSA from growing.
Is that true?
Where can I get PO4?
Should I increase my current dosings?
What should I do?
You can get phosphate from anyone that sells dry ferts. You can also get it from fleet enemas. Low phosphates seem to be the reason GSA occurs, you may also have GDust A that is caused from high light, reducing photo period helped me.
You should dose dry ferts if you want to control the dosage of what is going in your tank. And it is normal to have gsp on the glass. Just scrap them off during water changes, imo. A better dosing plan might reduce the gsa on your plants.