Can you explain why? I'm trying to understand.
Plants when driven hard enough "prefer" higher concentration of nutrients. So a large dose after a water change to bring up nutrients into high enough concentrations to feed the plants what they need. Remember, light is driving growth. So more light require more CO2 and nutrients to fulfill the plant's demands. If you're slowly removing nutrients daily, you'll have to dose more to keep them at a high enough level to feed the plant's fast growth, which may by troubling because of the daily water changes.
All i can think of is possibly having to use more of both.
If you run 8 hours of light a day, say from noon - 8:00pm, you'll be fine if:
CO2 on @ 10am.
Fertilizer dose @ 11:45am.
Lights on @ 12pm.
CO2 off @ 7pm.
Lights off @ 8pm.
Water change(s) anytime up until CO2 goes on for the next day.
If you can determine how much you are removing per day, your livestock load (NO3 + PO4 production) you can determine your amount needed to maintain a target level.
For example, if your targets are:
And you know how much your livestock are adding and how much you are removing daily, you know how much fertilizer to dose per day to maintain these target levels. Watch these levels, watch TDS, and perform a formal water change if they start to creep up. If TDS and these levels are lowering, we can safety dose more to meet your target goals.
What is "EI"?
Yes, I have a 4 head dosing pump. Could always add another unit if needed.
4 head head pump is all you need.
1 for macro's (NPK)
1 for micro's
1 for Excel / Metricide 14 (if needed / wanted)
1 spare of for a ferrous gluconate or similar product (if needed).
EI stands for Estimative Index -- a dosing regime based around 3 x macro doses and 3 x micro doses per week, on alternating days, with 1 day as a rest / 50% water change day.
I don't think a standard EI regime would work in your case.
Another thought. Dose your RO water with everything so your tank will always be at the exact same level... Exact same theory as your reef only with all plant nutrients instead.
Target your RO water with nutrients, supply that to your tank @ consistent levels, and your levels shouldn't move.