RV Repair: holding tank repair, hot glue gun, fibreglass repair

Question
Ron--Any suggestions on repairing a plastic grey water holding tank in a '95 33' southwind m/h?  Itis cracked around the drain pipe and begins to progress up the side.  I am contemplating plastic welding?  Any thoughts on two part epooxy and fibreglass repair kits.  Syon makes one for tank repair.  But i haven't heard very favorable reports.  What might your thoughts be?  Thank you for your anticipated input.---Jack

Answer
It's been my experience that tanks crack because of stress being put on them and gooping something on the crack does not relieve the stress, it cracks right back again.
Once you figure out what that is and relieve that, I have had good luck by cleaning the area with sand paper and a good cleaning fluid and using a hot glue gun with a good epoxy strength glue stick (not the cheap all purpose ones that came with it). I have also had good luck with two part epoxy's but the same rules apply, relieve the stress first, clean the parts good and it should hold.
Some RV manufacturers have the habit of trying to support the drain assembly, I think that wrong.  The tanks should be supported good and the drain assembly allowed to hang under it's own weight.  My Pace Arrow did the same thing, I changed the configuration, did the above and never leaked again until I traded it for a Winnebago (seem to be a little ahead of Fleetwood in how they do things).