Need to regretfully cut open my deck and replace my tank horrific leak somewhere up front, it is currently aluminium 80 gallon, these are very expensive new, are the poly tanks any good? they are half to a 1/3 the price of aluminium, has anyone ever repaired their aluminium tank, I'm guessing the tank would have to be cut open to see how much interior corrosion has takin place, I have seen some $50-$100 below deck 40-60 gal used poly tanks on Craigslist, and several used aluminium, however not sure about putting a used aluminium tank back in!