can you buy acrylic silicon from home depot that is good . i seen that theirs like an acrylic based one . butt i dont think that means anything i was thinking of sealing my acrylic tank just to do it .
Silicone and acrylic doesn't mix. You won't be able to get a stable bond. You need to use solvent based acrylic cements. ie. Weld On brand products. Not sure if HD sells that. If you are thinking that you need to maybe reinforce some seams, I would recommend Weld On 16. It's a bit thicker than the usual solvents which are like water. Easier to lay down a nice bead where you want it.
You have to understand that acrylic tanks are put together entirely differently than glass tanks.
The silicone in glass tanks serves as an adhesive and sealant between two separate panes of glass - a glue if you will.
The Weld-On products used in acrylic construction is actually a solvent that literally melts separate sheets of acrylic and re-forms them into a single solid piece. That is why it is called "solvent welding" rather than glueing. It is the same principle as welding two sheets of metal together.
The result is that you cannot "re-seal" an acrylic tank like a glass tank. You can make repairs to cracks by applying the proper Weld-On to the crack then refinishing with increasingly finer grit sandpaper like you would repair a sheet metal damage on a car, for example.