Hi, I am having my concrete pool deck redone and they satrted ripping up the deck today and I noticed the skimmer walls were just crumbled, so I took it out. I need to replace it before Monday when the deck guys come back, so I'm going at this alone. A few pool stores down here are trying to sell me a Hayward Auto skimmer? box that looks like it's twice the size of the one I'm replacing. The old one is only 14 inches long and the Throat is 3 1/2 inches and it's a bluish color. The pool guy is saying to just buy the Hayward, which is much larger and has a throat thats like 7 inches long and a mouth opening of about 10 inches, mine is only 9 inches wide and it's 12 3/4 long. This is my first skimmer box replacement job and I'm not sure of the differences. The pool is older and small it's only a 15,000 gallon pool..thus the smaller skimmerbox? The pool guy said to just widen the opening on the pool wall to make the Hayward fit? If I do have to put a larger skimmer throat opening against the pool wall, how or what would i fill the gaps with. Please help...!thanks