tank in balance but not the light nor plants

Ok I do not have an aquatic green thumb!
This is my second tank in 4 years. I started adding plants 3 years ago. I failed before but not like this.
A couple of weeks ago I tried to treat the leeches (2") and nematodes and I managed to kill off several fish (an Oto, 3 sids, 4 neons). My Discus are breeding again so they must be hardier then most. Now all I am doing is 50% wc weekly and daily Seachem dosing.
My rooted plants don't get good root systems going. The Diatoms seem to just move around the tank. I have new growth on most plants. But since I only use The Seachem products and not CO2 they are growing slowly. I now have a lot of GSA and not sure but may also have some GDA. Some of the green came off in small sheets.
I want to find a balance for my tank but I don't seem to be able to do this.
The only other new thing I am doing is putting heavy bath towels on the front of the tank. An hour each morning the tank has direct sun. I have read that some fabric can still let UV rays get through. So I wonder if this is my problem?
As everyone here has said reading the web for info is to confusing. You never know what info is erroneous or not. So how do I find a balance? Several of my plants died from the Diatoms. Three of the fast growers have a lot of new growth and I think I need to cut out the lower part of the plants which are gross with Diatoms. But then I think I will reduce my plant load again and this will not help my situation. Diatoms going on 8 weeks. Most of the plants left below are wasting away.
I have run all my tests on my water even though EI says there is not a need. Those parameters are fine. So it's my light (size and or time) or something else.
I am so frustrated. Since my health has failed this is my only hobby. I want to get this right. Besides I love planted tanks with fish. Have any idea's?

 

The lights are on for 10 hours. I use uncoated tiny gravel and about a quart of Ecco complete.