what can I do to help my plants?

[dreamwallaby]

This is my first post I didn't think I was going to care too much about plants when I started redoing the tank but now I am obsessed. However, my plants don't seem to be that happy. I have moneywart, red foxtail, green foxtail, java, anacharis and dwarf sagitaria.
The java is getting black/brown splotches, the moneywart has some leaves also turning brown and others that are drooping. The red foxtail has lost most of it's lower leaves(possibly my gouramis are eating it?)
Gravel bottom, I add API plant food once/week.
Light is T8, 15w, Aqueon floramax but there is a thin plastic top on the tank between the light and tank. It's a 44gal tank but only 35 gallons is water, 12-14" water depth (top of tank belongs to frogs/newts)
Ammonia, Nitrite are 0, Nitrate is 5ppm. Water is on the harder side. Ph7.6
I don't have a CO2 anything but I have a bubbler and the spray bar from the canister is set high up so I am sure atmosphere CO2 is getting in the tank.
Any suggestions or ideas?