Plant Supporting Substrate?

[KrystaK]

To be honest I'm looking for a sand substrate (As I have cories)
I currently have Tahitian Moon sand from Carib sea, which is great for the corries and looks really nice, but my plant's aren't doing fantastic.
I have a small bag of fluval plant stratum which I have used with the potted Amazon swords I have... I don't want to use it on the whole tank floor as it comes in small loosely compacted balls, and when disturbed they turn to dust - and it's expensive!
 
I dose  rougly weekly with plant ferts, have the light on for 8ish hours a day and have a fermentation based CO2 system in the back 9And a bottle of CO2 booster which i don't use, but may try to see if it helps. 
 
I've been told that sand isn't ideal for plants as it's harder for their roots to get into, but I don't know if I believe it

 

[ythao01]

black fluorite sand sounds like exactly what your looking for. there might be even better substrates but as far as I know fluorite sand is the best and it's safe for Cory's. it requires a lot of washing tho just like many other sands. N I actually think sand seems better for plants then gravel, but I could be wrong.

Your plants may just be getting use to your water if they're new. new plants will do that and melt but once it gets use to the water it should come back super healthy. I don't see why else they would not be doing good, I mean you're doing everything right for your plants.

you could also try root tabs to substitute for a plant supporting substrate, but you're already using frets and I don't know if over doseing on nutrients is possible or if it will have an ill affect on the fish.