Cleaning old aquarium?

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Suzisuzisuzi

Black Skirt Tetra
MFK Member
Jun 19, 2019
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I have a small tank (5 gal) that I am considering moving my betta sorority to so I have room in my larger tank for the danios my child wants. This was my first ever tank and aside from its small size it is sitting unused because it last housed a group of fish that all suddenly died when a new fish was introduced, I'm assuming from some disease I don't have the experience to recognise since water parameters looked good.

I'm worried the tank and filter pump might still have remnants of whatever disease killed off the previous residents. Is there a safe way to sterilize an unoccupied tank?
 
Empty everything and clean with bleach.
This. Soak all equipment in a weak bleach solution, I believe 1:10 works, and spray the tank down thoroughly with the same solution. When all soaked and done soak again in a concentrated dechlorinated solution (5x normal dosage) and also overdose dechlorinator when filling the tank again. You'll be safe then!

Also, make sure to use completely plain bleach. Unscented, no foaming agents or anything. Plain bleach
 
Bleach works but I tend to scrub my aquariums out with Bar Keepers Friend, which has oxalic acid in it, and it removes the water stains really well.

The acid is not that potent to humans but you should wear rubber gloves.

This Will Destroy any stray microbes in the tank.

Tank ornaments and lids can all be washed with week bleach.
 
Thanks guys! It makes total sense that extra dechlorinator would help remove the bleach residue.
 
Not that it won't work, but you could just spray the whole thing down with peroxide and then add water and add fish. It is highly unlikely that you have some fish disease in there that would survive a bath in peroxide. Peroxide will kill MRSA. Bleach requires a clean surface as it is a disinfectant and not a cleaner and its disinfectant properties are hindered by the presence of dirt.

Also, if you use Vinegar and Bleach separately, it could be more effective than bleach. I can't find the study I read on that now (only mom and pop health websites), so I won't say so definitively. Still, it is as effective on MRSA as bleach. However, the two substances would be harmless to fish given a rinse out with some water (peroxide would be fine without a rinse given a few minutes to turn into oxygen and water). No dechlorinator necessary. It is also safe for your kids to help with.

Basically, unless you're trying to make sure you're not going to get HIV from touching it, peroxide by itself would be all around safer for you and your fish and neutralize any microbes or pathogens that would be dangerous to your fish.

Just figured I would offer an alternative.
 
I give old tanks a good wipe down to clean off the glass. Then I fill them up, put a HOB filter on & dump a healthy dose of bleach in. The HOB will circulate the bleach water solution. I do this for 24hours, then completely drain & refill with a healthy dose of Prime/Safe
 
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I like to allow everything to completely dry out for 48 hrs after cleaning with bleach. Then refill and start over with Prime/Safe to neutralize the oxidizing agent. Peroxide should be fine as well, as previously mentioned, but personally I feel better after allowing a complete drying period before placing the tank, filters etc back in action.
 
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