How do you wash sand so it becomes clean enough for fish to survive?

Answer 1

If you mean before it is put in the tank then a good wash in a bucket is the normal thing. If on the other hand you mean how to remove the rubbish from gravel/sand in the aquarium already, then a syphon will usually lift the rubbish off the top. There are commercial air driven gravel syphons available at most pet shops.

Answer 2

When you purchase aquarium substrate at a pet store or aquarium supplies dealer, you only need rinse it with clean water, prior to setting up the aquarium.

If for some reason the aquarium environment becomes contaminated with toxins or pathogens from a diseased fish, you will need to remove all healthy fish to a different aquarium, or completely clean the aquarium and start with fresh substrate, filter and treated water.

If you want to clean your substrate instead of simply replacing it, you'll need to ensure that all pathogens are killed and toxins removed. To do this, clean with natural agents only (vinegar and baking soda, hydroxen peroxide, and/or washing soda), rinse multiple times very thoroughly to remove residue, and then spread your cleaned substrate to dry in a tray outdoors where the sunshine and fresh air will have a natural antiseptic effect. For fine sand you'll need a large wire mesh or plastic mesh strainer to do this. But in most cases it's easier simply to purchase new substrate, and spread the old substrate on your garden or houseplants - the plants will love the nitrates, you will save a lot of time, and you won't need to worry about pathogens or toxins lurking in the substrate.

Answer 3

Do not use any special tank cleaner or anything. Just use plain old water and this is the same for cleaning your tank. It may harm the fish and they might become stressed or even ill.