If you are buying a classic round tank, we recommend a base of 7mm bluemetal with a depth of 100mm. Allow 100mm extra around the diameter of your tank. Treated pine, bricks and pavers are all common materials used to make boxing for a tank base.
If you have a slimline tank, we recommend a concrete base of 25MPA, 100mm thick with F62 mesh through the middle of the mix.
We do not recommend sand bases for our tanks unless they are built on site.