I've got a 10gal fully cycled tank with a few fish in it and a couple of weeks ago bought a 29gal from Petco. I asked a question I think a day or two ago about transferring everything to the new tank and would my cycle start all over again, answers assured me that as long as I ran my old filter along with the new for awhile to let the new one start it's own BB, everything should be Ok.

Well, now I've thrown another kink into that plan and basically going to ask the same question again. I was in their store today and they had a 40 gal tank, with hood and glass top on sale for almost what I paid for the 29 gal.

The 29 gal was at home and still in the unopened factory box, so they let me bring it back and I've now got a new 40 gal tank. I also bought a fluval 150 watt heater and an AquaClear filter for 50-70gal tanks, figured the more horsepower the better maybe over the 30-40 gal filter.....

The filter I've been running in the 10gal that has BB in it already is also an AquaClear, however it's size rating is for 10-20gal tanks.

With this now extra volume of water over the 29gal, will I still be OK running the old and new filter until the new one is ready to go or am I looking at trouble with the BB in the old, small filter not being able to keep this much water in check ?

Should still be ok. youre only talking about another 11 gallons. Are you transfering everything to the new tank? Gravel, plants, decorations... If so, then use the same water from the 10 gallon as well, You should have a bacteria colony in the new tank in no time.

dante322...... Hey, now that's not a bad idea with the gravel. The AquaClear filters have 3 compartments, one the say to use charcoal in, I don't like charcoal so that's the perfect replacement for that..... Thanks

With an aquaclear, it's all in the sponge - it won't be up to speed immediately, and I would go slow on stocking, but it'll get you there quickly. You have to give the bacteria time to multiply to fill the new medium, but it will.

I guesstimated 30 days, maybe 6 weeks running the old finlter along with the new filter, you think that's enough time or need more for it to take a hold ?

Just so you know, no need to transfer water as the water holds no bacteria at all.

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I wouldn't put the gravel in my filter. I think what was meant is to trabsfer all of your gravel to the new tank. Gravel will have a lot of your beneficial bacteria and will help transition the new tank. I would also consider plants as an option.

If you are planning to change the look of the new tank, and want a different color substrate. You could always put the old gravel in a mesh bag of some kind, (posibly a sock or an old pantyhose) place it in the new tank, and after the cycle is complete take it back out.

Are you planning on keeping the 10 gallon running?

Well, I'm in a quandary over what to do actually....... I've got the regular sized aquarium gravel (black) in the 10 gal and I like the black bottom, but to buy enough more of that size gravel for the 40 will cost a small fortune. Was thinking about the black blasting media at tractor supply for the new tank.

Only problem with that stuff I've heard is keeping live plants planted in it. I've thought about using what I've got and mixing it was the blasting media but think that would look kind of weird with the mixture of both sizes.... so right now, I don't know what I'm going to do Saturday when I put it together and change tanks.