Daft Question

[sif]

Thgis is probably a daft question but... If you put the filter from a new tank into a mature tank for a couple of months, then fill the new tank with 1/2 old tank water and 1/2 tap water the new tank should be to all intents and purposes cycled and ready for fish - right?!

I know there will be min-spikes after the introduction of fish etc but the filter will be fully populated with bacteria and thats it?

 

[andywg]

I wouldn't worry about the old tank water, it contains next to no beneficial bacteria. But what you have described is known as "cloning" and should work fine.

Just make sure you don't go mad and try and fully stock the tank at once and you shouldn't have any problems.

 

[rdd1952]

andywg is correct about the tank water. All you're really doing is putting dirty water in the new tank. It won't help with the bacteria. Cloning does speed the cycling process but by no means will your new tank be instantly cycled. You will still have to go through the process of adding ammonia (fishless cycle) and testing but it will definitely be faster than cycling from scratch. If you cycle with fish, there will probably be enough bacteria on the filter for 2 to 4 fish to begin with. After that, you will see a mini cycle everytime you add new fish. Just be careful not to add to many at a time or you will get too big of a new spike.

 

[andywg]

I beg to differ, it all depends on the stocking level and size of the fish in the tank before. Especially when trasnferring from on eto another.

I successfully cloned enough material to instantly cycle a 55 US gallon tank from my 100 gallon which was cycled from my old 35 gallon tank. There was no spike or anything, I just moved the filter media from one sump to the other and put the fish in.

I agree this will not always work, but if you are using established filter media then the tank is instantly cycled. There are bacteria in the filter media to converte ammonia to nitrite to nitrate. If you are unsure, then err on the side of caution with the stocking levels.

Another useful thing is to take some of the substrate (especially if it is gravel) from the old tank and put it in the new one (in a tights foot if you want to be able to remove it).

 

[rdd1952]

I'm certainly no expert on cloning tanks but if you take enough bacteria (via the filter media) from a tank (your 100 gallon) to fully cycle another tank (your 55 gallon) it would seem to me that even though your 55 was cycled, the 100 gallon would suddenly experience the spike as you have basically cut the bacteria colony in that tank in half. As I said, I have no experience with that, just seems to make sense. There is only enough bacteria present in a tank at any time to process the waste of the current inhabitants. If you remove a large portion of that, you should get some kind of short term spike.

 

[sif]

Ok so you are saying that it will work, thats going to save me some hassle!

I must admit to being a little confused by the bacteria thing. I suppose that the number of bacteria is directly proportional to the amount of waste? If i therefore put an internal powerfilter into a tank that is mature running with an external filter will the internal colonise with bacteria at the expense of the external... OR does the bacteria just grow anyway to a limited degree everywhere?

 

[andywg]

It will grow everywhere, and the fact that the bacteria are already present and established means that they will be able to colonise the "spare" media - once the two tanks' filters are split - in a swift time preventing anything other than a mini-spike of the like which happens when we add fish, over feed etc.

The bacteria will not be running at full whack, but will recover quickly enough.

 

[frannyscho]

I have just done this with the filter from a 6.5gal tank, I ran it in conjunction with the new virgin large filter for a 45gal. I gently squashed the dirty old filter sponge onto the clean new one to set it off, and then ran both filters together. I put a net bag contaning some of the dirty old gravel and a dirty carbon pad next to the sucky bit of the new filter, and introduced my old fish from the smaller tank straight away after the tank water had settled down a day or two later. The recorded mini spike was as follows including new fish during the lowering nit spike
Day 1
Am. 0.3max, Nit. 0.1, Nat. 8-10ish
Day 2
Am. 0.3max, Nit. 0.2, Nat. 8ish
Day 3
Am. 0, Nit. 0.3max, Nat. 8ish
Day 3,4,5,6
Am. 0, Nit. 0.3max, Nat. 8-10ish
Day 7,8,9
Am. 0, Nit. 0.2, Nat. 11-15ish
Day 10
Am. 0, Nit. 0.1, Nat. 8ish
I then have put half of the old sponge off the first filter in the centre of the new filter, and replaced the old filter half with a new in the first one and popped it back in the smaller tank for a nearly instantly cycled first tank Am 0, nit 0.1, nat 8ish

All fish look happy so far in spite of being over enthusiastic myself with the new fish, plus three tiny platy fry only 1 day old. Water can't be that bad if they stay alive...keep fingers crossed.