Actually, the CO2 is fine. In my 75G, I keep it between 37-54ppm. And it's virtually algae free now, under 520W CF lighting.
As for my water here, it's also fairly soft. Just recently tested at kh 60 and gh 60. gh used to test at 70, but the last couple weeks has been 60. For my potassium, I dose just a little more than the EI, plus with the potassium nitrate dosing, since my plants don't seem to be growing alot, the nitrates just keep increasing with my dosing. And for my swords, they all have root tabs under them as well.
As for the algae being diatoms, well, mine only gets like this under 130W lighting. When I had it cleaned up and under 65W, things looked pretty good other than the corkscrew vals still looking shabby after the last blackout. But I still have yet to conquer this, like I did on my 75G when it looked like this. Switching to Travis' schedule worked wonders for that tank. But I tried with this for over a month, and then switching to EI with the same results, just not working for this tank. So I'm guessing his dosing is for very high light, large tanks, and heavily planted. So maybe we just need more plant mass. I definitely need more stem plants as well.
My goal is to succeed. So no, I'm not going to use a hammer, LOL. If I can get it to work, then it's just that much more I've learned in planted tanks. And as you can see, I still have a long ways to go, LOL.