Flourish trace has all the micros with no Fe, just follow the directions. And feel free to spam away, no worries
Can't understand how your tank is 90par at sub.
I have the same light, same bulbs and I have 130par max in front of the tank.
Could you please post your 20H dimensions?
Mine is 22x14x16 inches.
Its 24x12x16 inches
Does your light have one reflector for all four bulbs? That sounds like a lot of PAR, especially if we have the same bulbs
Could be your PAR meter is better than mine. PAR meters begin to struggle with extreme red and blue spectrums. A 660 red will be giving the plants a lot more than what the meter reads.
My par meter is a converted lux meter with a different sensor and calibrated to read PAR. Its probably ball park at best, esp when it comes to extreme sides of the spectrum.
But all par meters fall short in that regard so Im not sure how much difference a better meter would actually make.
I just measured it again, last time the bulbs were only a day or two old, thought they may not've been burned in yet. Yep, mid 90s
Bulbs are front to back: 3000K, 420 actinic, powerveg 633, Giesemann flora