Help! Slow recovery

Ok so I had a bout with some brown algae/slime crap. It seems to be gone now but I cannot get new root development. The plants look pretty healthy but the roots aren't popping out. I am using an 18 site aeroflo2 with Canna nutes. Water temp is 68 pH is 6 all under a T5 ho floro.

Any suggestions to get the roots going? I dont want to lose my girls.

Hygrozyme and/or h2o2 and /or root stimulater and /or superthrive

thanks...anyone else have comments? I have used hygrozyme regularly and got this slime. Cleaned all the slime and let it run for a few weeks ...no slime....add hygrozyme....got the slime. I had always used hygrozyme in my last runs but I can't add it now for some reason.

Maybe high temps in root zone or low oxeygen