Don't use playsand... it's really no good for fish.
It compacts underwater.. nasty pockets of toxic gas form in it, and all the fish poo etc sits on top of it..
Pool filter sand is the way to go. I didn't have to rinse it, and it doesn't compact underwater.
I paid $12 Canadian for a 50 pound bag.
If you read the original post you will notice that the guy wants to put plants in it.
Playsand is perfectly OK for a planted tank as is Silver/Dry Sand (which is the same sand just sterilised).
I have used playsand in my previous set up and dry sand in my current setup and never had these problems you are explaining.
With plants in it as long as they are allowed to grow their roots there will be no problem with anaerobic pockets.
To say that it is harmful to fish is just scaremongering.
Andy
you can not call a warning of this type, that is backed up, scaremongering. its a fair point well made, playsand, can and does, according to these posters, humm and you, compact and trap noxious vapors. though it is fair enough to say it will not happen in a planted tank. how can it be scaremongering to warn people?
indeed it would be remiss of anyone who knew this, not to have warned those who don't, kinda one of the points of having a forum.