How long can a filter be turned off before bacteria die?

[Topkath]

I've heard that you shouldn't start running a filter that's been turned off for some time, as the bacteria die, and then you pump toxins back into your tank, but how long is OK? :?:

[Nathan]

im pretty sure they live for about an hour hour an a half, not 100% sure mate. why do you need to turn it off in the first place?

Nathan

[Topkath]

My tank cracked overnight - visualise water all over the lounge room floor - fish swimming in 1 inch of water in base of tank.... - obviously filter was running dry for some time. Am getting a new tank with new fish and just need to get a head-start on getting the filter back up and running before the new tank arrives.

[sharn]

ohh bummer!

just hook it up as usual (it will probably chuck some gunk out into the water) and let it run for a bit, you will probably see a mini cycle, if not a full one if all the substrate and media has gone dry. if its still wet hook it up to a mates tank, hooking it up to the bath etc probably wouldnt work cause the bacteria would die from temp/chlorine shock (could always put heater in bath?)
basically as long as its wet it you should still have a bit in there, the can die of oxygen starvation also.

[FishLover]

No, no, no. Don't just turn it on. You need to clean up the filter before turn it on. The dead filter could be deadly to your fish.

After about one hour or so, maybe two hours if you push it, the bacteria in the filter is dead. You need to clean it up before turn it on.

[Merrilyn]

I'd begin to worry after an hour. The bacteria in your filter will begin to die off soon after the filter is turned off, and there is no water flowing past the bacteria bringing fresh oxygen.

If your filter has been turned off for longer than that, then you need to clean it out thoroughly and restart your cycle.

Save as much as you can from the tank in the way of gravel and plants. So long as they remained damp, there will still be some nitrifying bacteria clinging to it, and this will give your cycle a kick start.

Watch your ammonia and nitrite levels, and be prepared for daily water changes while your tank goes through a new cycle.

[sharn]

would the dead bacteria not give the new ones something to feed on? i didnt mean turn it back on if the fish are in there, sorry for not explaining better :)

[Topkath]

Thanks All...

Am running the filter in a plastic crate with fresh treated water to start cycling it and have put some of my plants into the water to help. (My fish are currently in another plastic crate with an old smaller filter getting lots of water changes.) My new tank is coming tomorrow, :D so, here's hoping!!!

Thanks again for your help.