Waterproofing Chest freezer, silicone, liquid rubber, polyurethane ?

[jlc123]

Hi, I have been given a large chest freezer (not working) but I would like to convert it into a tank. I tried to silicone the seams on the inside but unfortunately it had a small leak, I am in the process of removing the silicone and was wondering if there there is a better option to make it water tight ? liquid rubber, polyurethane anything else ?
Thanks

 

[jlc123]

Also the inside appears to be powder coated aluminium.

Thank you

 

[BIG-G]

I think probably the best option would be a pond liner.
Then you wouldn’t need to worry about sealing or metal coming in contact with the water.

 

[fishdance]

Pond liner is the safest.

PU sealant - polyurethane will stick to old PU so if the first attempt leaks you just add more and more.... Some brands will yellow with sunlight /UV if tank is outdoors so choose carefully if that's important to you. Structurally integrity remains the same.