When I had a shallow sand bed I used a gravel vacuum when I did water changes. They don't seem to make the one I have anymore. To start the syphon you just pump it up and down in the tank. It's nice and long which gives the sand plenty of time to separate from the crud.

Will 1" of sand bed support a sifting star and nassarius snails? What would be a feasible method of "washing" the sand free of nitrate and phosphate?

Would replacing it with a coarse crushed coral be more beneficial and would that support the livestock?

Magickiwi, short answer is no.
Longer answer is some reading here:
http://www.reefkeeping.com/issues/2004-12/rs/index.php

I use a gravel vacuum and vacuum all the sand to its full depth on all waterchanges. The sand is only 1/2" deep.

If your sand is more than 1/2" deep and you do not regularly vacuum it you do risk exposing black anaerobic areas and releasing hydrogen sulphide. So if you haven't vacuumed, but you want to, you have to start slowly by only going through the top 1/2" of the sand, and continually going a bit deeper on each waterchange. I've had tanks with up to 6" sand beds that I vacuumed to their full depth, but it was done regularly and no anaerobic areas were allowed to form.

Vacuuming your sand bed used to be common practice until the DSB sand bed craze/fad started, now 15 years later we are wondering if it is OK to vacuum again. generally I feel that if you have a shallow sand bed vacuum away (1" or less) if you have a deep one and haven't vacuumed be for be car full as you could release pockets of nasties that can with out your tank. if you have a deep one you have to vacuum regularly to prevent these pockets for forming (as in weekly)

as for the argument that it is taking stuff away from our sand bed that needs to be there for the bio diversity of a functioning sand bed, thats a bunch of bunk, there is no way a hobbyist can create a fully functioning DSB as we cannot support the biodiversity required for it to work properly.

Steve

i'm pretty sure our tanks are too small and have too many predators of the sandbed guys to worry about much biodiversity in them.

SUCK IT!

^ your sand...

How much sand do you have to replace when you do this in your 90G ?

I am just going to siphon out all the sand into a bucket. Might replace it if it ends up looking to ugly but it will only be thick enough for aesthetic purposes.

I don't vacuum but I do rake it. Or at least unused to before I inherited a sand sifting goby from Brettski.

I used to use this..

http://i1002.photobucket.com/albums/...ps86maip54.jpg

.. And let the particulates that I kick up filter into filter socks on my return. It's the only time i'll use filter socks too. General I keep the socks off otherwise.

Do you miss all the forking you used to do before I helped you out?