Keeping the aquarium clean is imperative to maintaining excellent water quality but should you clean the sand?
Well this depends upon what type of sand bed you have implemented into your aquarium.
If you have installed a deep sand bed to aid with aquarium filtration then no you should not manually clean it. With a deep sand bed the cleaning needs to be performed by what I call critters. These are things like small starfish, micro fauna etc. The burrow through the sand and keep it clean on your behalf – natures cleaners.
If you have a shallow sand bed, use sand for decorative purposes etc then yes you should clean it. Over time a sand bed which is not used for filtration will end up with uneaten food, fish waste, detritus etc contained or clogged within it.
I always recommend to install a clean up crew into an aquarium. Putting a clean up crew is basically purchasing hermit crabs, snails, shrimps etc to assist you with the cleaning of the aquarium. Some of these animals will assist in the cleaning of the sand and others will not.
Even if you have a clean up crew in the aquarium I would still recommend that you manually give the sand bed a bit of a clean.
Basically all you need to do is gently stir the sand when you are doing your water change. When you stir the sand all the detritus etc will lift up into the water column and you can siphon it out with the water. Dependant upon the size of the aquarium you might not be able to clean the entire bed so just start at one end and clean as much as you can. The next time you do a water change start where you left off.
Simple to do but definately worth it.