Do I need to use any substrate?
• No, a lot of people run reef tanks without any substrate. If you don’t put any substrate in a reef tank the glass bottom will soon be covered with natural life anyhow e.g. coralline algae
• I use substrate because I prefer the natural look of it and like to have extra space for beneficial microorganisms to inhabit.
• Substrate can harbour organisms that can be advantageous to the tank (see live sand).
• Ensure that you wash any new substrate very thoroughly.

What substrate should I use?
I always recommend fine coral sand (2mm particles).

What and how much Substrate should I have?
• For a Salt-water tank make the substrate as thin as possible so it won’t harbour as much organic waste. The thinner the substrate, the less anaerobic-bacteria will be able to form in it that may later be disturbed.
• If you are trying to create a live sand system the depth will vary depending on what method you use (see the questions on live sand).
• Any substrate that is added to a tank with live rock will soon become live.

When should you add the substrate?
• The way some people establish their tank is to delay the addition of the substrate for up to a month. The advantage in doing this is that any debris that comes off the rock can easily be siphoned off. This would mean that the tank would mature earlier.
• The way I suggest is to add a layer of substrate about 2-3 cm thick at the same time as the rock. Ensure that it is stirred regularly. This method takes longer though it has its benefits. This way you can establish a stronger colonization of microorganisms thoughout the sand, which may have been previously siphoned out. This will result in extra filtration in the long run. If you adopt this method the rock will take a lot longer to cycle and delay the safe addition of fish for a bit longer.

Why is my substrate binding together?
• You need to stir it more regularly or introduce creatures that will stir it for you.
• This can occur if you are adding too much calcium or buffers.

by Paul Talbot