You clean sand like this;
put a small amount of sand in your bucket (no more than a quarter full; large loads take longer!)
fill the bucket with water and give it a good stir
pour off all the dirty water; don't worry if you lose a little bit of sand
keep on doing that until all you have left in your bucket is good, heavy sand that sinks after a minute or so. It's a long, tedious job, there's no way of pretending it isn't, but it's well worth it
I have mostly Java ferns and anubias that grow on rocks and wood, but I have a few cryptocorynes that grow in the sand and some cabomba. I used to have some sagittaria that grew beautifully, but I moved it and it didn't like its new spot and died! You could try vallisneria; it does well for a lot of people, but doesn't like my soft water. Amazon swords have done well for me in the past, as has Indian fern/water wisteria.
My user name doesn't have anything to do with my career (don't have one of those, as I'm disabled
) I'm a big Chris Cornell fan and it's a combination of two of his song titles; Flutter Girl and Moth (and I really like moths
)