Summary:
SWG is probably the way to go based on convenience but not economics.
SWG require longer pool pump run times increasing your electricity cost.
Recurring daily costs: $1.17 daily SWG electricity vs $1.29 daily bleach (not considering any hardware / salt / acid / etc.)
Time commitment: 2 hours per year hauling bleach / jug recycle. 10 minutes every 2 weeks pouring bleach into tank.
If you are going to buy a SWG, a higher capacity SWG will last longer and require shorter pump run times.
Full Text:
I agree with the use of a SWG. I do not use one because I have a pool with aluminum sides and am afraid of the potential corrosion. If my pool had more corrosion resistant construction materials, I'd have one.
The convenience is worth it.
But economics is another thing. Each person's situation is different. In my case, I don't run my pump any more than 3 hours per day: that's all it takes. My Stenner pump puts in 1 ppm FC per hour or run time but could be set to run it in faster. I run my pool pump for up to 3 hours for filtration and circulation. If I had a SWG and ran the pump 12 hours per day, that's an additional 9 hours of pool pump time that I don't need.
Math - the hard core numbers
9 additional hours for my 1000 watt pump and $0.13/KWH electricity - 9 hours x $0.13/KWH = $1.17 per day extra electricity cost
87 oz of 6% Walmart cleaning bleach @$1.77/gallon (provides 3ppm for my pool) - 87oz x 1gal/128oz x $1.77/gall = $1.20. Now add sales tax: $1.20 x 1.075 = $1.29 per day bleach cost
Final electricity cost vs chlorine cost for my situation $1.17 SWG electricity cost vs $1.29 bleach cost
So not considering any costs for installation of Stenner vs SWG, hauling bleach, or for salt / muriatic acid, the extra electricity cost required for longer SWG run times almost pays my chlorine bill. I only run my pump 3 hours in the hottest part of the summer. Right now I'm running it for 2.5 hours per day. Everyone's situation is different. I don't like hauling bleach, but only do it a few times per year. I go to a small "Neighborhood" Walmart, order the bleach in the store, and go back and pick it up. I am not driving around looking for bleach. i buy 40 gallons at the time because that's what will fit in my vehicle. It will all fit in one shopping cart (stacked up in cases). The 6% bleach is the cheapest in my area AND its more stable than the higher concentrations. I don't worry about manufacturing dates.
If I bought a SWG, I'd want a larger one that would last longer and require less pump run time. I'd also want a variable speed pump to reduce electricity costs. You need to be sure that lower flow rates in the slower speed modes will allow the SWG to produce chlorine. The following chart may help decide which SWG is right for you
Compare and Review Saltwater Chlorine Generator Prices and Features
The reason to do a SWG is convenience and it's a BIG reason (you don't have to handle the jugs). Use your your specific numbers: additional pump run time needed, pump watts, electricity costs, chlorine costs, SWG or Stenner pump costs, and your DIY abilities.
Using my numbers, I can't see how the SWG is an economic advantage. The additional pump run requirements essentially negates the savings in my situation. But still, if I didn't have concerns for corrosion, I WOULD have a SWG.
My Stenner chlorine injection system is easy. I only check FC and pH weekly on Sundays, other labs once a month or after major rain and drain event. It's so stable I'm considering decreasing my checks to once every 2 weeks. I opened the pool in March at 1 ppm FC daily. I later went up to 1.75 ppm and am now at 2.5 ppm FC daily additions. My pool maintenance time is getting the leaves out of the skimmer basket and pool cleaner bag. 95% of the chemistry maintenance is taken care of by the daily Stenner chlorine injection.