# Maintaining bio-filter without fish



## darkfalz (May 7, 2006)

If I have a tank with no fish in it, how long until the biofilter dies off?

Any cheap way to keep it going? I'm not sure if I'll be able to find pure ammonia. Maybe a small pinch of fish food every 2 days, then a vacume and 50% change before I put a fish back in?


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## emc7 (Jul 23, 2005)

Feed the tank the same amount of food you would feed the fish you intend to keep it the tank, or that amount of other organic stuff (frozed vegies, shrimp) then do a 100% water change before you put the fish in (the biology is in the filter and the substrate), if you feed it less the biology will survive at a lower level and you will get a mini-cycle when you add fish. A 50% change may not be enough to lower the nitrates (depends on how long the tank has been set up and if you are doing regular water changes in a tank with no fish). 
Or since you have multiple tanks, move the filter (unless its a UG) to another one with fish in it and move it back when you get more fish for it.


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## darkfalz (May 7, 2006)

How long with no fish before the bacteria die off? Could it go a week?


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## TheOldSalt (Jan 28, 2005)

It'll have some fallback/dieoff in a week, sure, but not enough to likely cause you any real problems. 
Ammonia works a lot better than feeding, since you don't have to grow other bacteria first which make the food rot, along with the fungus which often accompanies it, and of course you wouldn't have to make a massive water change afterward.


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## darkfalz (May 7, 2006)

I'll see if they have any at the hardware store.


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## dwool36 (Jan 31, 2006)

Dollar stores are a great place to get pure ammonia.


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## rcomeau (Apr 23, 2006)

badmanstropicalfish.com helped me understand that you should use Ammonium Chloride instead of Ammonium Hydroxide to avoid low PH as a result of loss of buffer. I looks like you can get Ammonium Chloride at sciencelab.com.

My guess is that you need very little Ammonium Chloride to keep the bacteria alive. Much less than trying to start a cycle.


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