75G Bow front planted tank -- need some help/advice

[Kwis]

After looking through all the beautiful planted tanks that people have, I have to say I'm a little embarrassed to share pictures of ours! But I'm going to have to, because I could use some help..

About a year ago now we started a planted tank in a 20G long planted tank filled with 3 inches of black flourite substrate. We had a horrible light system ( my husband built one for the tank with 4 regular curly daylight bulbs ). Yes I know it sucks, but it's all we had for the time being. Anyway, things weren't working out in there at all. Constant algae blooms and I could not get rid of the diatom algae. So a few months later we transplanted everything into a 75 bow front.

Everything is currently in the 75 now. For substrate we actually have potting soil topped with a couple inches of regular river rock. For lighting we were using 3 T5 bulbs and this weekend just switched over to LED. Also have 2-2L pop bottles for c02. PH in both tanks has stayed the same and has been fairly high (7.6+) But this has more to do with our city water as it's pretty hard water. I can honestly say I've never tested for Nitrates and other recommended things. If I do and they are low/high - how do I change that?
The plants are doing OK, but they're not thriving either. Every now and then they will look great (perky and green) but then we will get a nasty bloom of diatom algae that just won't seem to go away. Could definitely use some advice, please!

I use flourish fertalizer in the tank a couple times a week.

 

[Kwis]

Here's some pictures of the tank now. For fish we have 1 rainbow shark, 1 dinosaur bichr, 1 gold ram, 2 platinum gourami's, 1 blue dwarf gourami and 2 angelfish. For plants: LOTS of wistera, that's pretty much the only thing that will grow in the tank. 1 little crypt plant, some dwarf sagitaria and a type of large sword plant ( I forgot what it's called but it's red and green ).

Oh yeah, also have a 300 GPH external canister filter. That was newly added about 2 weeks ago. But as you can see, the wisteria is still covered in (what I think to be) diatom algae and has just been looking a lot more droopy lately.

 

[Kwis]

I should add we are completely new to planted tanks. I have had many, many fresh water tanks throughout the years so aren't new to the fish. But plants are another story. My husband knows very little about fresh water plants, as he is used to salt water aquariums.

So no judging.

We want to add more plants to the tank, but everything we had added so far has pretty much died out. Aside from the wisteria and sagitaria. We've tried Ludwigia Peruensis, Dwarf Grass and most of the java moss is gone. There's a little lump of java moss I was able to salvage and I stuck to one of the pieces of drift wood. It looks like it's been doing OK so far.