Needing Help Growing Plants Successfully

I have been in the hobby for awhile. But I am unsure with what is causing the plant growth in my year old planted 55 gallon aquarium to be poor . Been trying different things to help with the plant growth but doesn't result in good plant growth. Here are the details of the aquarium

55 gallon

Lighting: 45" Fluval' plant 2.0

Par level 70 at substrate

Lighting period: 8 hours

Substrate: Turface' pro league

Fertilizer: nilocG' thrive plus liquid and aquarium plants.com root tabs

Dosing: 3 pumps twice a week

: Co2' automated with ph controllerand runs into a
external reactor.

Co2' 30ppm tested by ph test and kh test then using c02 chart

Ph:6.6

Kh:4

Gh:5

Nitrates: 30 ppm

Plants: Hadi' red pearl, jungle val, cryptocoryne' undulata, juncus' repens', micro chain sword, Christmas moss,amazon frog bite.

Jungle val is currently melting along with the cryptocoryne undulata. The only thing I can think of that made them melt is adding hydrogen provide to kill the black beard algae on the micro swords. There is one Hadi red sword that is staying small and not growing tall. It produces new leaves but stays small. It is in the middle of the 2 swords. All the swords look like they have either nitrogen defiency or chlorosis.Juncus repens is not growing.

All of my plants are low lights plants. Is the par' at 70 to much for them? Any advice on what I can change? Is there a better way to distribute c02 then a reactor? Should I be using a ph controller?

Thanks I'm advance