The best cleaning method for used tanks

+1 Use bleach to clean and disinfect and use vinegar to remove calcium deposits (if any).

 

Bleach works very well. You can use sodium thiosulfate to neutralize if that concerns you. A 1:1 ratio of sodium thiosulfate to bleach works. The other advantage of bleach is that a little goes a long way.

 

What should I use to clean a used 55g tank? It was freshwater but I will have saltwater in it. When I got it it was covered in algae. It had 4 large circles of green algae on each side, but it was dry. I've got almost all of if it clean now, using distilled white vinegar(I think I used 1/3c vinegar to 1g tap water) Just some algae in the scratches in the glass left to get. The silicone seals on each corner are dried with algae too. I think I'll have to cut out these silicone seals one at a time and re-seal them with aquarium-safe silicone/epoxy.