I am shopping for a salt chlorinator for my 14K gallon pool and came across Aquarite. A couple of pool stores only sells the 40K cell while I know there are 15K, 25K cell for this model. The salesman said in Arizona, during summer the 15K cell will not be able to keep up with the chlorine demand. Is there any validity to this claim? The 15K cell is like $300 cheaper, so I was wondering if the stores are just trying to increase their margins.