Hello fellow s.fl.'er
What is your fertilizing regimen? Look into this link about balancing your nutrients with your light and co2
. Consider doing some form of EI since you have pretty decent lights.
I feel that H2O2 is a last resort. It works.. but perhaps too well as it'll get rid of some other things. You can spot dose (a limited amount!) with a dropper onto the leaf right before a water change if you want to go a little more conservatively. What's a limited amount? I figure an amount that totals to half of the "safe" amount of h2o2 from the one-two punch method mentioned above or less if you don't need it.