I've gone with sand substrate for the first time..it looks lovely... I have one problem though - when I do the weekly clean the suction doesn't suck up about half of the fish poo [sorry] but does suck up sand. As part of the clean which will sit there and cause nitrates presumably.

Anyone else have this problem? Am I doing something wrong?

Thanks

About an inch above the sand you can swirl the syphon in a circular motion and this should create a little 'tornado', this should bring up the poo but not the sand (obviously though, you are going to get some sand sucked up)

Siphoning off sand is a technique that takes a while to learn. It's a much more delicate technique than vacuuming gravel. You will inevitably get some sand but with practice you won't lose too much. I actually prefer to use a piece of airline tubing for this. It's a bit more time consuming but very effective. For bigger tanks though it just wouldn't be practical. Keep at it and you will eventually get the hang of it.