Maintain cycle temporarily

[Oli]

Hi guys, after shifting over existing media into my new tank to quick start the cycle, I have found the fish I want won’t be available for a few weeks. Is it worth shifting over my two dwarf gouramis into it (from 60 litre to new 200 litre) just to maintain the cycle for a few weeks? Then moving them back. Would this be cruel/stressful?

 

[connorlindeman]

Hi guys, after shifting over existing media into my new tank to quick start the cycle, I have found the fish I want won’t be available for a few weeks. Is it worth shifting over my two dwarf gouramis into it (from 60 litre to new 200 litre) just to maintain the cycle for a few weeks? Then moving them back. Would this be cruel/stressful?

As long as the parameters and that far off it should be fine for the fish. You could ghost feed the tank. Add some fish food into the tank so that beneficial bacteria have something to eat. I've never tried it though.

 

[TwoTankAmin]

It would be a much better idea to add ammonia to the tank. There are a few facts about the bacteria of which most are unaware. Because they do not form spores, they have developed a method for survival longer term when they sense they have lost their food source and/or oxygen. They go doprmant- that is they basically go into a deep sleep. When what they need becomes available to them, they wake up and go back to work. Morover some of them will become motile and be able to seek out better places to live. Of course in a tank this doesn help since there is nowhere to go. But im nature is can and does work.

But what happens if an established colony experiences a drop or an increase in ammonia? The bacteria reproduce when there is more ammonia or nitrite than the colony can handle. This is how they increase their number in response to an increase in these things. Conversely, if the amount of ammonia.nitrite being produced decreases, they do not reproduce and as individuals die off, they are not replaced. If the supply of ammonia or oxygen is not shut off entirely, they will not go dormant, they will adapt their numbers accordingly.

What does this mean for your situation? If you put a couple of fish to hold the cycle, their bio-load needs to be close to or greater than what you will be adding with the new fish.

I would suggest a much easier method would be to add ammonia to the new tank. Depending on the size of the new tank and the planned fish, I would add 1 or 2 ppm of ammonia (or ammonium chloride) to the tank. Think of it as doing a fishless cycle with seeding. The easy part of this is you dont have to worry about a rigid ammonia dding schedule. You only need to add ammonia every few days. Just test the tank for ammonia before you add the next dose to make sure ithe tank is at or near 0 ppm before you add it. If it is not, then wait another day and test again. Also do a weekly water change. This will keep nitrate from building up too high.

An interesting thing about the bacteria is that research has shown that once established they respond really well to pulsed ammonia. That is a decent dose and then nothing for a while and then a decent dose again. This research came from the waste water treatment industry which deals with high ammonia levels that are not consistent. They worried that the bacteria would die back under such conditions but discovered the opposite. The bacteria were able to resume activity as soon as what they needed returned. Of course this was not over extended periods of starvation but rather days or weeks.

So by adding 1 to 2 ppm of ammonia while you are waiting you should have the tank well cycled by the time the new fish arrive, The gouramis need not be caught and moved twice.

The problem with moving media is there is a point at which one can move too much and that can causes issues in the tank from which it was taken. Also, how much bacteria actually makes it to the new tank will determine how long it takes for one to make that tank ready for new fish. I normally suggest trying to move no more than what would be about 25% of the bacteria out of the established tanbks and then using ammonia to get the 25% to increase in the new tank so it can be stocked without worrying.

Under good conditions one can double the amount of bacteria in under 24 hours. So if you can move over 25% it should only take a few days to get it to double twice. Once it has then feeding ammonia every few days will keep the tank safe for the new fish. Just be sure to do a huge water change before you add them because you should have nitrate building up.

If you have live plants involved and there are more than just a few, you should be able to use 1 ppm of ammonia to get the tank to where it should be safe for the new fish.