Here's my thing -
My tanks are lightly to moderately planted, all have decent community bioloads as well.
I don't use PMDD for one reason: I've got it stuck in my head it'll add too many nitrates, which I struggle with as is.
Here's a recent pic of my 55 gallon, to give an idea of plants:
In that tank there is about 30" of fish (4 dwarf cichlids, 3 small rainbows, an oto, 4 pygmy gourami, 2 male guppies). Nitrates are 20 ppm for weekly water changes, changing out 15-20% water weekly. That tank has 160 watts of t12 6500k light, on about 12 hours a day.
I recently finally got past the diatom bloom of h-e-double hockeysticks after adding a bunch of newly found hygro.
Then I added DIY CO2 to that tank... and the algae blooms are coming back.
I know I need to add ferts, but am scared of skyrocketing nitrates... am I being silly, I hope? PMDD ala Greg Watson help, hurt? Help me out here understanding.