change from my 15 gallon column tank to a 20 gallon long tank, could I simply transfwr over my existing water in my 15 gallon and my filter and have jt cycle? I'm nkt too thrilled with my column tank...
No need to transfer the water as well, there's nothing but nitrates and other wastes in it. Just move the old filter and if possible the substrate as well, then refill and add the fish back in once the water is at the right temp.
When I switch/move tanks I will use a 5gal for all the fish, often times a good portion of that water goes back into the tank.
ok thanks so just transfer existing filter and heater
(I like transferring about 30-50% of the old water just to avoid any potential shock to the fish so it's more like a large water change... but it's not necessary. 100% change is fine as long as you follow the advice above )
good plan on transferring the current filet with all media. that's what's gonna make your tank stay cycled & safe. if you do see any blip in ammonia it will be brief and probably easily managed with prime
I probably would do the water as well simply because its what they are used to and you wouldn't have to acclimate them to the new tank.
I'm the same, I like to use 50% of my old water if the parameters are good.
Filter, substrate & decore getting move over is enough to maintain your cycle. Changing the water is a personal preference issue.