Oh dear....where to start? Ok....I will tell you the things I see that you are doing wrong. There are so many that I'm only willing to give answers.....not explanations. Feel very free to disregard my advice.

ph..should be 5.6-6.2....not outside that range. 7.8 isn't going to cut it. It's YOUR job to keep ph in check.

A one gallon res that you change every two weeks? Are you keeping them in a milk bottle? Your rez....(especially YOUR res with those nasty roots) should be changed completely every seven days no matter what size it is.

Your plants are three months old? They should be several feet high by now so they haven't been "flourishing" for awhile.

H202 3% percent should be used at 2-3 teaspoons a gallon.....try two and then kick it up to three if it's not enough.

I'm not even sure what to say about your roots.....that's just plain scary.

PS....I just learned yesterday from rhizome that the fox farm nutes are three part nutes and you only have one of them.....where are the other two parts to your nutrients?

All in all....not great. I Let me dig up my link to plant problems. You have a very large amount of work ahead of you.