My tank is a community tank but I like having a background full of plants.. the problem is everything keeps dying on me! A few of my plant have just rotted from the roots up. My bogwood plants have black dots all over them which I don't know what they (see pic) are the rest have brown spots.

This is what my plants are:
1x Vallisneria gigantea
2x Moss balls
1x Amazon Sword (Echinodorus bleheri)
1x A plant that looks like Vallisneria gigantea but with thinker leaves
1x Bog wood plants (3 species growing on bog wood, 1= small round green leaves, 2= Kind of moss like long threads 3= Java Fern)
I feed weekly with plant food and have removed my carbon.
My tank is a 50 gallon (200 litre).
Ammonia= 0
Nitrite= 0
Nitrate= was 10-20 but my test kit is faulty so haven't been able to test for a week
Any advice on how to keep my plants alive without damaging my fish (in my sig.)? Or are there better hardier plants that I could buy?
Thanks
Gemma

This is what my plants are:
1x Vallisneria gigantea
2x Moss balls
1x Amazon Sword (Echinodorus bleheri)
1x A plant that looks like Vallisneria gigantea but with thinker leaves
1x Bog wood plants (3 species growing on bog wood, 1= small round green leaves, 2= Kind of moss like long threads 3= Java Fern)
I feed weekly with plant food and have removed my carbon.
My tank is a 50 gallon (200 litre).
Ammonia= 0
Nitrite= 0
Nitrate= was 10-20 but my test kit is faulty so haven't been able to test for a week
Any advice on how to keep my plants alive without damaging my fish (in my sig.)? Or are there better hardier plants that I could buy?
Thanks
Gemma