Help with dying plant

[huangism]

I bought these plants from a chinese fish store, they were very healthy when I bought them. They have been in the tank for over 2 weeks now. They are growing very vertically and leaves are smaller than they should be. They should be carpeting the floor but it is doing the opposite and now the leaves/plant are turning yellow from the bottom up. I think the tank is a 10g, the lights came with the tank. I have a white fluorescent and a blue light as well. I am not very knowledgeable about these things. The fish has been in the tank for a long time and so have the moss ball and those needle like plants. If someone can ID both plants it would be greatly appreciated it. The chinese store person called it pearl plants (in chinese). Here are the pics, I want to save them but I don't know why they are dying. I had the really common plants before (the one with mesh leaves and sells from every pet store), they died as well. It was growing nicely but after a week or two the leaves seem to grow smaller and the bottom of it just starts to fall off.

I just started feeding liquid food a few days ago. I was told to add it every 2 weeks, 5ml per 38 liters.

This is really frustrating as I want a nice green carpet but just can't seem to get there. Please help in any way you can, thanks for your time and efforts

 

[Atxpunx]

I see glossostigma. Look that up and see if that's your plant. Glosso(for short) is a high light plant that requires carbon dioxide injection. They seem to be reaching for the light which means insufficient light. If your unsure of the bulb type a picture might better aid us solving your dilemma.

 

[huangism]

yes that's the one, I did look it up now and it looks exactly like what I have got.

The light I can switch but CO2 I don't have, is it required for it to survive? how much do they usually cost? what standards of light should I be providing it with? the light I have got seems bright but i guess it is only a perception