Old tank cleaning/disinfecting

[earhtmother]

So I've had a couple of tanks develop slow leaks at side and bottom seams. This has necessitated aquiring some cheap tanks for temporary housing while getting the original tanks resealed. I'm reasonably sure none of the **new** tanks and filters etc would have contained sick fish etc before being sold but.....
I can't use bleach so vinegar & peroxide are my usual cleaning go tos. How paranoid do I have to be about leaving residue once I clean them? I need to get these tanks up and running ASAP so any help is appreciated.
I guess I should say that the *fish* going into the tanks are a Betta, some Amanos, L144s(BNs), Bumblebee Cats, Upside Down Cats and Hoplos

 

[BBradbury]

Hello mother...

There's nothing that could infect your fish in the old tanks. Whatever bacteria or anything else has been gone for some time. So, what's left is simply old, dried organic material. A bucket of warm tap water with a couple of tablespoons of aquarium salt and a new sponge is all you need to clean things up.

B

 

[earhtmother]

I was hoping for an *easy* fix but wanted to make sure