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post #1 of 4 Old 08-26-2009, 08:30 PM Thread Starter
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Tank upgrade


I'm buying a 46g tank to replace my 20. I know some people do this all the time, so maybe there's a 'best practice' you can share?

I'm assuming I can do some sort of short cycle, but would love to hear about your standard practice. Can I just move substrate and filter and be fine??

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post #2 of 4 Old 08-26-2009, 08:56 PM
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If you transfer everything from the 20 over to the 46, including the filter, you should not experience any cycle problems. If you add on to the number of fish you have, that can cause problems. Add any new fish slowly and test water daily for a while.
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post #3 of 4 Old 08-27-2009, 12:44 PM
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Agree with Twistersmom. The issue is to ensure sufficient bacteria are in the new tank when the fish are added. If they are, the tank is immediately cycled, plain and simple. I always dose the tank with a biological supplement--partly to be safe, but also because I usually clean the gravel and clean or replace the filter media and this removes bacteria. Seachem's Stability is very good, it is live bacteria and immediately seeds the aquarium. As long as the fish load is not greater than the bacteria in the tank (from seeding and Stability) there will be no more stress on the fish other than that of being netted from one environment to another. And of course assuming your water parameters are basically the same (temp, pH and hardness).

In July I set up my (empty) 115g and moved the plants, wood and 112 fish from the existing 90g into the 115 the same day; gravel was pre-washed and dried, and new filter media. Later in the week I tore down the 90g, cleaned it, new filter media, and moved the plants, wood and 85 fish from the existing 70g into the 90g the same day. No fish losses in either case. I also dosed the tanks with Stability for two days just to be safe. I consistently had zero ammonia and nitrite readings.

This is really no different than adding some new fish to an established aquarium. The bacteria in an aquarium exist at the level in porportion to the ammonia and nitrite available from the fish and biological processes. When you add new fish, the bacteria have to increase to handle the additional ammonia and then nitrite. They can do this quite quickly--about 7 hours for nitrosomonas and 13 hours for nitrobacter/nitrospira in normal aquarium conditions. They multiply by binary division, so in 7 hours the nitrosomonas bacteria have in actuality doubled in numbers--provided of course there is enough ammonia in the tank to warrant this. Having plants in the tank is even better, because they consume more ammonia (and it is now believed nitrite) than all the bacteria. I've explained this in another thread.


Byron Hosking, BMus, MA
Vancouver, BC, Canada

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian. [unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]
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post #4 of 4 Old 08-27-2009, 01:59 PM
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When I did these 'upgrades' I simply took ALL filter media out of the 'old' filter, placed them in the new one (which was usually larger) and filled the rest with new filter media, took all plants & rocks over to the new tank and filled the new tank up about 50% with water from the old tank and added the rest fresh, had that Combo run for few days and then went fish-shopping. Hadn't had a problem once with it.

BUT if your current tank has any sort of sicknesses going on I'd not suggest that and rather start from scratch with the new one (you'd not wanna also transfer diseases to your new tank)
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