we switched our tank over to sand this weekend, looks loads better. just used playsand, it takes a fair bit of washing but it's not too bad, here's my little step by step guide
1 - get about 3 times as much sand as you want to put into the tank
2 - get half a bucket full of sand, run a hose pipe into it and stir it all up so the sand is mostly floating in the water, you'll get a load of scum rising up, when the water level is at the top of the bucket remove the hose pipe and scoop off the scum from the top, give it 2/3 minutes and most of the sand will settle, if you put your hand in the water it's easy to tell when most has settled. pour off the water form the bucket, you will loose a load of sand too, don't worry about this. The actual clean sand particles will sink quickly, all the other bits of debris will stay floating longer so you'll end up getting rid of most of the mank.
3 - repeat this process several times, you'll only get the sum the first 2/3 rinses, then you'll start to see loads of particles of debris being washed away.
4 - keep repeating this process until the sand settles within a few seconds and there's no debris left on top of the sand, you'll loose a lot of sand in the process, don't worry about it. You can expect about a third of what you started with.
repeat the whole thing until you have enough washed substrate for the tank.
this is best done in the middle of the day in the summer....... done it at 10 at night in the winter once and it was very very cold!!
