i have 96w over my 20H and everything seems to be growing great!
i dont have hc but i do have hm that grows low to the ground and all over the foreground actually. dose seachem's line of ferts per their rec. chart and ~30ppm of co2 i plan on switching to GW ferts that i have when the seachem stuff is gone and i have switched to pressurized already.
i had the HM growing all over the front and covering the downoi but i have since cut all the HM from the downoi area to the diffuser out for another tank.
also to add i have a 2.5g with 18w coralife pc over it and it grows riccia and HM low to the ground as well and that tank has no co2 or ferts just flora base and weekly w/c's