I just read a great post by Keith Berglind,the platicguy, about repairing plastic tanks.
We have had a lot of success in repairing fiberglass tanks. As long as the damage is not too great, along a seam, or covered in chemical (e.g., herbicide or pesticide), we get a good, long-lasting repair. We use fiberglass fabric, gel and hardener.
We have not had much success with repairing plastic tanks. We are going to try again using some of Kieth's techniques and materials. Thanks Keith.
Andrew Greess - www.qspray.com