replacing the gravel?

[Lauren]

I have this cheezy blue gravel that I want to switch out for a natural color. What is the easiest way of doing this? I was thinking about removing my fish and plants, then netting the old gravel out. That way, I won't have to remove my water and say so long bio filter. Is this the best way of doing it?

thanks,

Lauren

[OrionGirl]

Do you have an under gravel filter, or a reverse flow UGF? If not, then you won't lose much of the bacteria replacing gravel. The water does not contain the bacteria that consume ammonia/nitrites, but you will want to keep some of it for the other beneficial organisms that colonize healthy tanks--maybe a gallon or two. I'd also retain some of the mulm from the gravel, as the plants will benefit from it. I'd pull down the whole tank, replace the gravel, and put everything back in but use new water.

[Lauren]

use new water? wouldn't that just absolutely destroy my bio filter? I was hopping to retain the water in changing the gravel, so that I don't shock my fish when I return them. I don't have another aquarium they can live in as the biofilter reestablishes itself. I have a VERY healthy biofilter that I’d prefer to keep as in tact as possible.

[OrionGirl]

Your bio filter is not in the water. It is in either a) the gravel, entirely if you run UGF, partially for most other setups or b) in the filter media in your filter. Sponges, bio balls, ceramic noodles, etc. The water does not contain the bio filter.

As long as the new water matches the existing conditions (pH and temp, GH and KH) replacing all of it will not shock your fish in the least. If anything, it will invigorate them by giving them clean water.

[Lauren]

so keep a gallon or two, but replace the rest of the water. Looks like I found a sunday project. Oh, and no, no under gravel filter or heaters.