pale microsorium any ideas?

[Hardstuff]

I have prior experience with high tech planted tanks but where I live now the water is liquid rock. 400 PPM Gh even higher Kh. So I reluctantly decided to go with r/o blend with some tap, say 20%. I am running Gh of 9 now & Kh 5, Ph 6.8 with co2 running & 7.4 without by morning time before lights on. The tank build is:
10 gallon
15 x 2 watts wide spectrum old school T8
small external canister, very small.
small powerhead with sponge injecting Co2 via compressed tank
flourite substrate
dose: potassium nitrate, monopotasium phosphate, flourish Fe, flourish
comp, plantax with boron

The plants are doing well, some anibias, wisteria, pearl grass, & some fast growing stems. Some of the plants I have to prone weekly. (The problem is the microsorium looks pale almost yellow unless I dose lots of Iron & K). Then I get algae problems with heavy fertilization. My only fish , a bleeding heart tetra does not like fertilizer.Most of the plants are growing well but NO Pearling. The microsorium roots are growing off the rock & into the soil. Is this bad? The plant itself is making babies & new leaves. Could the plant just be adjusting to new parameters. I feel I am close but the tank is low in 1 or 2 elements. Thats what you run into with R/O lots of tweaking. I make my own GH booster: calcium sulfate, Mg sulfate, potassium nitrate all 3parts except the mg which is 1 part. waiting on potassium sulfate so I can have less nitrates. Any ideas????