I have a ten-gallon tank with a flourite substrate. I also use DIY CO2 to get the pH in the mid six range at 3 dH. It loaded full of plants and I never get any algae except hair. Here's my fish load: one oto, one harliquin rasbora and recently, one platy and one xiphophorus variatus, which have had no effect on the algae. No green spot, film, brown, red, grey or whatever algae - just big balls of green hair. Much of it grows off the substrate as well as the plants.
I also have a five-gallon no-tech tank with a soilmaster substrate. It's full of young xiphophorus variatusis and platies. There is significantly less algae on the substrate and plants. I suspect the iron and the addition of CO2 is the only physical difference other than the plants. To me, it looks like the high iron and CO2 levels promotes the growth of hair algae. I could add nitrate and phosphate but I've been resistant because I don't want to introduce other problems. I just pull out any clumps of hair alage I see during the water change.
I will never use fluorite as the substrate again. I may use it as a first layer, but never alone again.
Andrew, MASI Treasurer
This message is always under construction: 75-gallon tank; 2, Eheim 2026 filters - one twice broken; Tek Light with 4, 54W T5s (6000K) ; Sand on top of 4:1 sand:clay mixture; Milwaukee CO2 controller; PlantGuild vortex CO2 reactor; pH = 6.6, kH=70mg/l, GH=120mg/l; EI; Flourish excel on 50% weekly water change: AGA Member.