Backyard Aquaponics
A place to discuss aquaponics

reference .Going to start work on fish tank ,just been undercoating and painting facia boards etc. getting ground ready for foundation to house fish tank, sorry about picture

With the work you're putting in, i'd have just made custom growbeds and lined with a good pond liner..
IBC's are not the best growbeds as i've found out - The uneven bases cause lots of nooks for rubbish to get stuck.

I'll be (once i can afford) ripping out my 5 x IBC growbeds and replacing with 3, 2mx1m timber boxes lined with pond liner.

Hi thinking about grow beds rather than replacing your existing grow beds ,why not fix wooden board to the bottom and seal to make water proof, this would give you a flat fitted surface then add pond liner or other material that makes wood waterproof.