Pogostemon and bad gravel?

[neelhound]

Hi its exteemely difficult to get new gravel for the running tank ive got as its all been set up and theres a lot of gunk deep under the gravel that the gravel cleaner doesnt get(not anaerobic,plants make use of it, but still not enough space to come up everywhere ,its settled). I mixed in some 'ECO' substrate, but onyl a bit a while ago, its decorative gravel with some white sand that tends to go underneath. Im growing a few plants in this gravel with tropica plant nutrition + and floursih excel, co2 AND about 55w of t5 lighting and 2x36w t8 lighting in a juwel rio 180. What low growing plant would be ok in this gravel and also tend to not float as im having problems with some blyxa(although its growing well, thanks tdi-line(originally owned by))?thanks