I am thinking of building another stand and getting a 125g tank. The problem is the only place to put this tank is where my current 75g sits. I would need to move my 75g to the opposite wall (125g tank is too big to go there).

I will have to nearly empty the 75g tank of all water since the gravel alone is 100lbs and will have to move the fish to something temporary. I have an old 20g tank that I may setup and put the fish in there while the move takes place. I think I will be able to keep enough water to keep the gravel in water, but will taking the water down that far cause my tank to cycle again? I am assuming it will, but also assume since the gravel/filter media will be largely untouched it will be an abbreviated cycle?

If I use the spare 20g tank to hold the fish during the move I would only use it for a day maybe. This would be to give the water heater time to warm up the new 65 or so gallons. I have a deep well system and the water can be pretty chilly. I don't have city water.

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i would think that a large percentage of that beneficial bacteria live in the gravel and inside your filter. i would try my best to keep some of the old water from the tank somewhere so to limit the amount of new water you're putting into the tank.

maybe fill up the 20gal and maybe a few buckets to pour back into the tank? i wouldnt think you would cause the tank to cycle again by draining it that much =)

keep your filters running in a bucket of the tank water, try to keep the water like an inch above the gravel and save a few buckets of the water to put back in.i did read something somewhere about if you do a 75% or larger waterchange it tosses your tank into a mini cycle same thing as a regular cycle just way shorter. (1-2weeks maybe) if your able to save about 50% of the water you should be fine. so figure 20gal. tank+ water to keep gravel wet + another 3 5gal buckets should be enough to keep you from cycling

Thats not true, I do lots of 75 to 90% water changes all the time. There is no good bacteria in the water column, its all on the gravel, tank glass, deco, plants and filters. In moving just put the fish in the tank, keep filter running in a bucket of tank water, all deco and rocks needs to be kept wet. Add new water, close to the same temp as the 20 gal, dechlorinate and you should be fine. If you clean the gravel before putting it back into the tank do it with tank water so as not to kill any bacteria, or wait for the tank to settle then do a good gravel cleaning, using what ever python or such that you vac the gravel with.

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Sorry O_O. need more internet police cleaning up bad info on the web.

I moved the tank and saw a small reading (.25ppm) of ammonia, but it went away after one day. I thoroughly vacuumed the gravel while i was pulling water, kept my filter media in a bucket of tank water, and moved all 41 fish to a 20gal tank with a pump in it to move and aerate the water. Pretty happy with how well the move went.

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