Permanent structural Acrylic construction requires a "weld" achieved with a solvent cement.
Weldon 4 for bonding close fitting joints and I think it's Weldon 14 that's a gap-filling version, (I think 14 is effectively 4 with acrylic dissolved in it to allow it to fill gaps).
This might be an ideal application for Finite Element Analysis software to ensure your wall thicknesses keep distortion within acceptable limits, don't forget permanent cross bracing at the top of long tanks to prevent the long sides from splaying,

- Nick