This tank is junk now, eh?

[UncleJT]

Add a thick block of glass at the inside corner and silicone the hack out of it. It will be buried in the sand and won't have cosmetic issue.

Couldn't this potentially cause more problems since I'd have to cut away some of the silicone in that corner to get the glass block to butt up tight in the corner for the block to work correctly? IIRC correctly, newly applied silicone also doesn't bond well to cured silicone.

 

[sumpmonkey]

You are correct new silicone does not bond to old silicone.I have seen tanks with more damage provide years of service.