I generally prefer to buy everything online. However, I want to make sure that I am not compromising the sanitizing or water balance of my spa. Are online products reliable? Are they different than what the dealers provide? Any advice regarding online sources for chlorine systems? I live quite far from my spa dealer and don't really want to "drop by" there for supplies. The dealer has told me that they will "set me up" initially with everything that I need and I should return intermittently to purchase those same supplies from them.