[Jim]

I just purchased the following fertilizers (85G planted discus tank) from Greg Watson, but am confused about exactly how to go about mixing these and frequency of the dosing.

Plantex CSM+B Plus Iron
Mono Potassium Phosphate (KH2PO4)
Potassium Sulfate (K2SO4)
Potassium Nitrate (KNO3)

I think these are the right macro/micro nutrients, but the more I read online to figure out the dosing question, the more confused I become. I typically do 40-50% percent water changes once a week and think the estimative index method would be the right way to go.

Based on the following about my tank, can someone please help me figure this out in very simple terms? I have used Flourish products in the past and am new to this method -- I'm finding the calculators, etc. that are online to be a bit confusing.

Here's a rundown of the tank:

85 gallon
3.5 wpg light for 10 hours/day
Approx. 20 plants in the tank (a combination of swords, anubias, anacharis, hairgrass)
Fish load is moderate to heavy
Pressurized CO2 - 25 ppm
pH - 6.9
KH - 125 ppm (7 degrees)
GH - 143 ppm (8 degrees)
Nitrate - The test is not totally clear, but its somewhere between 0 and 5 (closer to 0)
PO4 - 5.0
Nitrite & Ammonia - 0
Temp - 84

I'm in the process of switching from very hard tap water to RO water (for my discus). I just introduced the RO water into the tank this wekeend (50 percent RO mixed with existing tap water in the tank). I wanted to avoid stressing out my fish, so I went for a 50/50 mixture. So far, so good.

Among other things, I'm trying to get my PO4 level down because I am dealing with an ongoing green algae battle (you'll notice its high at 5.0). This is another area of concern -- I know that I'll be adding PO4 as part of my dosing -- should I leave this out of the ferts mixture until my existing PO4 levels decrease?

I also added RO Right to the new water, but in hindsight I probably should have added less than it called for (given the high KH and GH already in my tank).

Any recommendations are greatly appreciated!

Jim