Hi,
The most prevelent upside to a SWG is that it provides the chlorine, instead of it having to be introduced manually. So, less "hands on" maintenance time of the pool. This also reduces the chance of chlorine spills onto hands, feet, shoes, flip flops, ankles, and feet. Also reduces the off chance of over-dosing the pool.
The SWG costs a bit upfront, but over a period of years, the cost of the SWG vs the cost of chlorine each week, pretty much evens out over a long time period.
A very noticeable benefet, is the soft feel to your skin from a SW pool.
It is highly suggested the SWG be at least twice the size of your pool. The reason why is then you would not need to run the SWG so much, which will greatly lengthen the lifespan of the salt cell. You should consider a SWG sized for a 20K pool to get the best bang for your buck.
There are quite a few good products on the market and would be difficult to compare each of them. Suggest to research and decide which couple of them best suits you. Once you narrow it down to a couple, we'll be happy to chime in with more details if we can.
Pentair (the most cosly cell replacement because the control is built into the cell itself)
Hawyard
Compupool (since they have fixed their problem in the last year or 2)
Autopilot
etc.... there are quite a few
Most of us use Solar Salt - cost is about 3.50 for a 40 lb bag. The only difference between the solar salt and "pool salt" for 7$ a bag, is how fine the salt granules are. Takes solar salt about 5 minutes to dissove vs the 2 minutes for pool salt.
I needed 12 bags to get my 15K pool to about 3500 ppm, so about 50sih $. Salt does not evaporate, so replinshment of it is only due to water leaving the pool due to splashout, backwashing filter, overflow from rain and the like. So, just how much is needed to be replaced each year is a 1 on 1 personal thing, but in any case it wont be much.
Downside (if you call it that) - up front cost of the unit, but again, cost evens out with manually dosing chlorine over time.
You may also want to put a timer on the SWG so you can run your pump independently of the SWG,(thats what I do) but its just a little added expense, but it isnt a requirement. Depends on how long each day you want to run your pump and dont need chlorine production the whole time the pump runs.
I dont know of any real downside.
No problem using it with Fiberglass pools.
THe thing about deteriorating stone is being stretched a bit by some folks. Not all stone is effected equally and SW really doesnt do much, if anything to concrete decking. Its true SW does deteriorate some of the softer stones used in poolscapes, such as Oklahoma flagstone, which is what the deterioration comments are mainly aimed at. (many people should be more precise in their comments about this). However applying sealer to the flagstone every couple or 3 years solves the flagstone deterioration.
