Swapping out brand new aquarium with 4 fish

[SnowMonkey]

Hello all!

I am completely new to this forum, as well as this hobby. A couple weeks ago I purchased a 60g tank/stand kit from PetSmart, and set it up about a week ago with 2 platies and 2 mollies to get the nitrogen cycle going. Almost immediately after putting them in, I noticed a small scratch/crack in the tank. I didn't think much of it but took it to a local aquarium store and they advised I lower the water and replace the tank ASAP.

Petsmart has agreed to replace the tank. However... they will not get another in stock until Saturday. This past Monday, I lowered the water to about half so it wouldn't cave, but the filter won't work with water that low. Fortunately, my neighbor happened to have a tank of equal temperature and fish compatibility, so they are staying there for now.

So my question.. When I replace the tank on Saturday or Sunday, is it better to fill it up with the water that is still in the old tank, even though it has been sitting there idly without a filter running for a week? Or should I just fill it up with dechlorinated tap water and start the cycle over? Any other advice on the situation would help as well.

Thanks in advance for the replies!

[ScotJudd]

Hi. The cycle in the new tank will depend more on the state of your filters rather than the water you put in it. Personally I would rebuild and fill with conditioned tap water and do a fish less cycle to prove the tank is suitable for fish. When 4ppm ammonia is reduced to zero with zero nitrites in 24 hrs, then do a major WC to reduce the nitrates that will have been produced and add the fish 24 hours later. If all the test results are good after a week then I would slowly increase stock, but only a few fish at a time. A good liquid test kit (avoid test strips, they are really unreliable) will be your best friend! As I said, that is what I would do but others may have different opinions. Good luck with the new tank.


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[jvann]

Personally I would say it depends on the type of substrabe you used. If you used gravel, it should be fine, however if you used sand, it'll cloud everything up for a day or two (not including the bacterial bloom).

However, one thing to keep in mind is that the bacteria "lives" in the water, but it doesn't stay in the water. It attaches itself to porous surfaces, hard surfaces, etc. The best place it grows is inside your filter. However, I would think that using the water from the tank already in your cracked one would absolutely save on the water bill if you're concerned about that. There shouldn't be anything wrong with using the water since the fish weren't in there long it really didn't have time to obtain a lot of waste.

[dalto]

I would use new dechlorinated water. You won't be saving anything except a few gallons of water by using the old. Also, water that has been stagnant for over a week would not be my first choice to use in a new tank

As others said, your bacteria is not really in the water it is on surfaces. If your filter has been dry for a few days there probably is not much there to begin with.