Kiko said:
What are the benfits of having a sand bed?
It provides a habitat for detrivores such as
pods and worms.
How thick should the sand be?
Depending on whether you want a
DSB or not, the depth can vary from 1" to 6". I used to advocate
DSB's and still have a 180g tank with a
DSB. However, after seeing some of the problems that seem to crop up with
DSB's in some peoples tanks, I now suggest that you research them and decide for yourself. You can certainly have a successful tank using a shallow sand bed.
Can I just use sand taken off of a local beach?
I would not suggest doing this for a couple of reasons. First, it's illegal in most places...not sure about Hawaii though. Second, beach sand tends to contain pollutants that you don't want in your tank. Have you ever noticed the foam that washes up on the beach with the waves? That is natures protien skimmer...most of the crud from that ends up in the sand. I would buy some sand if I were you...
JMHO.
What sort of sand should I look for?
You want a fine aragonite sand. You can use silica sand, but aragonite will help stabilize your alkalinity because it dissolves at a relatively high pH adding a natural buffer to the water.
Would it be unwise to add sand to an established aquarium?
Not at all...we do it all the time. One thing you don't want to do is mix sand with crushed coral or other coarse substrates. The sand will settle to the bottom. If you have a good pod population in your tank already, I would just change out the current substrate with the sand. Your critters will populate the sand quickly. One thing you might want to do, just for extra diversity, is add some sand from another established reef tank. Put it on top of the sand you add to your tank. If you wish, you can add some rubble on top of the sand in a few areas to give the
pods a hiding place.
