Actually, I hate to admint, this is the second time, I over-filled them both and poped them and had to have them repaired. Heres where I built a better base, glassed it in, then added tanks, then foam. Never miss an opportunity to work with marine foam if possible. I glassed the tops back on and painted. If I were starting over, Id cut out the top, then only cut out the top of the old tanks and use them as a bucket, into which I would place new smaller plastic tanks, THEN foam them in. I didnt get any pics from after I poured the foam, it was, well, really sticky and messy. I cant recomment enough using paper plates to help guide the foam along and use gloves, the stuff takes several weeks to wear away and its all over your hands in two seconds.