I agree, some of the quality of the stuff out there is not so good. I would only go with what others may have proved to be sound. I've only had one tank in the past where the sealer came loose from the steal and the company admitted they were having trouble with the material. Its a two part mix and pour. And yes, the tank needs to be 'clean'. This was a very long time ago when that happened and I do believe I got that stuff from JC Whitney. Since than I only use good brand stuffffffff. Guess you pay for what you get.