crack; 2" horizontal near top of tank (one on right w/control heaD)
I'd look at a Marine based epoxy resin to repair it. Might last a week, might last years.
Look at Marine Tex:
http://www.marinetex.com
You'd have to take it out of service, inspect it from inside to find the crack and find something that can seal it. I don't even know if there is such a product, but the tanks aren't very expensive. I wouldn't put the effort into it.
It CANNOT be fixed from the outside. It's two separate layers and the leak is probably not even where you see it.
it's a 16" x 65" tank; dealer i bought system from quoted $768 + shipping, so just under a grand.
unless someone knows a better priced source?