Are Salt Generators more economical than liquid bleach over the lifetime of the pool or just easier to maintain?
Are Salt Generators more economical than liquid bleach over the lifetime of the pool or just easier to maintain?
First, see this recent thread for a relevant discussion on this.
[EDIT] I have corrected an error I made below that waterbear pointed out in a later post -- I was off by a factor of 2 in chlorinating liquid quantity and therefore total cost. [END-EDIT]
Then, do the math. I don't know how much chlorine your pool uses, but let's say it's on the low side of a pool exposed to the sun of 2 ppm FC per day. Let's also assume you have a small-ish pool of only 10,000 gallons. That would require about 20.5 ounces of 12.5% chlorinating liquid per day or around 4.8 gallons per month. It costs me $3.50/gallon so that's $16.80 per month (for 10,000 gallons and 2 ppm FC per day). A similar anlaysis using bleach would lead to a roughly similar number. If you have a larger pool or use more chlorine per day, then the cost would be correspondingly higher. The 4.8 gallons corresponds to 8.33*0.125*4.8 = 5.0 pounds of chlorine per month.
Some salt cells say they can produce up to 1.5 pounds per day at around 150 Watts of power so that's 24*0.15 = 3.6 killowatts to produce 1.5 pounds or 12 killowatts to produce the 2.5 pounds of chlorine you need per month. Electricity rates vary, but even at 30 cents per killowatt, the SWG will only cost about $3.60 per month to operate (for 10,000 gallons and 2 ppm FC per day) so is much, much cheaper at generating chlorine than buying from the store.
An SWG costs roughly $1000 and the cells last, well, some say 3 years while others say 5 years -- it probably is getting better over time so let's just say it's 5 years and a new cell replacement is several hundred dollars. If we ammortize the initial cost over 5 years, that's about $200 per year. If the swim season is 6 months out of the year, then that's $33 per month. The ongoing cell replacement amortization will be about a third of that or around $10 per month, again assuming it lasts 5 years.
So, initially the salt cell is more expensive upon initial installation. As for ongoing costs, even in a reasonable best case of 5 year salt cell life, it is probably somewhat comparable to buying chlorinating liquid or bleach (ignoring initial installation and just counting chlorine generation and cell replacement). With a shorter cell life, the SWG would be more expensive. If your pool is much larger and/or used a lot more chlorine per day, then the SWG can become more economical, ignoring the inital installation cost (if you amortize that, then you are losing money during the first 5 years of use and it takes years to recover that except for the largest pools or very high FC usage).
So generally speaking, you buy an SWG for the convenience, not for the economy. However, after the initial installation, the ongoing cost (including amortized cell replacement) isn't horrible, but it depends on your specific situation.
Richard
Did I miss something in your example, Richard?
For the first 3 years, at $33/month vs $8.80 per month the SWF costs roughly 2 1/2 times what the bleach does. That means the 3 year cost of the SWG buys 8 years worth of chlorine. After that, the cost for the SWG is about 10% higher than the chlorine. So after 3 years you are 5 years behind the cost of the chlorine...and you will never catch up. But how much is the convenience worth to you? If the convenience is worth it, then it's worth it. If it's not then it's a bad deal.
Now suppose you are a super-high priced lawyer or doctor making $300/hour--If you spend an hour every month going and getting chlorine, your time cost outweighs the chlorine cost so the SWG saves more. Of course, you COULD hire someone to get you chlorine once a month--and it would not be $300 for the labor.
I suppose I could keep coming up with scenarios all night!:D ;) :rolleyes:
You also forgot to figure in the salt and acid needed vs the acid needed with bleach. Anyway, for me the convenience factor and the lack of water problems I have seen in my own pool and my customers pools vs. manual chlorination (a large percentage of my manually chlorinating customers use liquid!) to me far outweighs any added expense, if any, from a SWG. It is interesting that the ones who say that they are not really needed or are too expensive are the ones who have never owned and lived with one! (wink, wink Carl!;):D). I guarentee that when the day comes that they finally get one they will wonder how they did without one for all those years!Quote:
Originally Posted by chem geek
Bottom line is that I have found in my experience that pools with SWGs are more stable and have far fewer problems.
Carl,
You are right that the initial installation cost will not get recovered anytime soon. I separated out that cost from the ongoing cost of chlorine generation and cell replacement. I guess that makes my analysis useful for people buying a home that already has an SWG and figuring the ongoing costs, but isn't useful for a new purchase decision where the only reason to buy an SWG would be for convenience, not for economics.
Waterbear (Evan),
Yes, I screwed up. I used 1 ounce instead of 2 when I put the number in my spreadsheet. My bad. I will correct my original post above and yes, that would double the cost for chlorine, but the SWG generating amount would need to double as well so the payback from the allocated costs is faster. I'm glad more than one person looks at this! And yes, I didn't include the mostly one-time salt and the on-going acid costs (I don't know what those are so did not include those). Thanks for catching my mistake!
Richard
I guess it's like getting a camera in your cell phone. You don't need but you sure love having it!Quote:
It is interesting that the ones who say that they are not really needed or are too expensive are the ones who have never owned and lived with one! (wink, wink Carl!;):D). I guarentee that when the day comes that they finally get one they will wonder how they did without one for all those years!
Some additional thoughts around costs for SWC:
Expenditures:
Initial salt costs: Assuming a 20,000 gallon pool needing 12 bags of salt: $55.00 ($4.57/40# bag at Lowes)
2-3 additional bags per year for dilution, splash out, etc: $15
Muriatic acid: $4.87 per gallon @ Lowes, using 6 gal/year: $30
Cost benefits:
No algecide addition
No buying/hauling/disposing of bleach bottles, splashing on clothes, eyes, skin, etc. (OK, you may need 4-6 gallons over the course of a year to cover high CL demands)
Freeze protection provided by my SWC control system (no closing chemicals, time spent closing, broken pipes, etc) Of course, this will depend on where you live :)
If you're a "gadget guy", then you get one more toy to play with and explain to your buddies during bbq's, swim parties, etc. ;)
I don't think payback vs. bleach should factor into the equation to purchase a SWC system. Payback vs. being "Pool Stored" DOES factor in. But, if you're reading this, that's not a promblem for you becuase you've found this forum....
Carl,Quote:
Originally Posted by CarlD
The important point of my post was that pools with SWGs seem to be more stable and have fewer problems in my experience. (And we have a large customer base with varied types of pool, filter, chlorinating combinations.) Pools with SWGs and cartridge filters seem to have the fewest problems (while pools with cartridge filters on trichlor seem to have the most! No surprise here!).
Evan,Quote:
Originally Posted by waterbear
I'm not surprised you have had fewer problems with SWG pools. But remember, people who have found their way to PoolForum learn how to avoid those problems through education. Since I began as a newbie here, I've had two water problems in 8 years, both quickly solved--and not repeated.
It's a toss-up--do you educate yourself or toss out $$$ to compensate? I agree: An SWG is about the best and smartest way to spend money compensating for lack of knowledge.
You know MY opinion on tri-chlor--it's best if used on new hard-surfaced pools while they cure. Otherwise it's usually wise to avoid using it.
If $$ is tight, education is the BEST way to compensate--that's generally speaking.
Well, thanks to this forum I have overcome the baquacil nightmare & now I am knowledgeable in the bbb method. I just thought that if it evens out close to the same cost over time why not take the easier road with the SWG.
Quote:
Originally Posted by cnk
If that's your only reason, well, it NEVER evens out. It takes 8 years (about) just to catch up with the initial layout, then the cost of the new cell means it ALWAYS costs 10% more.
After 8 years of BBB you won't think twice about what BBB takes to do.
I haven't managed our pool for a full year yet so I don't have data for every month. Last summer our combined bleach and acid cost was about $25 per month. But since November it's dropped to about $5 a month. We've also cut our electric bill in half, partly by not running the A/C but also by cutting the pool pump runtime to just a few hours a week/month.
When I built my pool, I was going with a full equipment controller anyway and with the Aqualogic, to add a SWG only requires the cost of the cell which for me was about $400 so my payback was much shorter than what was described by some in this thread. But that is not the real reason I went with it. To go a week or even two without having to check the pool was a big plus for me.
If money is tight then a pool ususally is NOT the best investment!Quote:
Originally Posted by CarlD
If money is tight then a pool ususally is NOT the best investment! When you consider that SWGs have been in use in Australia since the 60's and there they are more the norm rather than the exception it makes you wonder why they took so long to catch on here in the states. Carl, I wish someone would give you one so you could live with one then tell you you had to stop using it and go back to bleach. I think you would sing a very different tune!;)Quote:
Originally Posted by CarlD
Don't get me wrong. Liquid chlorine is, IMHO, one of the best ways to manually chloriinate a pool but the popularity of inline feeders and trichlor show that people want a way to automate this task. SWG's are the way to go if you look at the chlorination automation methods available, IMHO (at least for resisential use)! Much more dependable and much eaier than using liquid chlorine and a peristaltic pump! Far fewer problems than using an inline feeder with trichlor (especially with a cartridge filter).
How does proper calcium balance affect a SWG? I'm asking because we have very hard water here. If this is yet another water parameter I'd have to adjust, not good.Quote:
Originally Posted by waterbear
too high a water hardness leads to more scaling of the cell and necessitates more freuqent cleaning
We have pretty hard water where I live and by summers end, the CH is well over 400 ppm. I keep the alkalinity and PH at the lower end of their acceptable ranges and it seems to keep the scale down.Quote:
Originally Posted by aquarium
Evan:
This statement contradicts so much of what we teach here. It is VERY possible to have a pool on a budget, and maintain it inexpensively. I can easily see why someone can happily have a pool, but cannot justify spending a grand on an SWG.Quote:
If money is tight then a pool ususally is NOT the best investment!
Our first pool was an inexpensive 15' EasySet on a homemade platform of rocks and sand. We used it HAPPILY for 3 years. The rules for maintaining the cheapest 8' donut pool are THE SAME as for the biggest, fanciest "infinite horizon" pool.
The ONLY item I would agree with you on is if you cannot afford a FAS/DPD service test kit then you cannot afford a pool.
I have REPEATEDLY said that I have NOTHING against SWGs, and HAVE toyed with installing one. But the little bit of time savings I will get is not enough for ME to justify it. I simply present the arguments that made MY decision.
I spend VERY little time actually maintaining my pool because I follow my own advice to stay ahead of my water. I usually spend 2 minutes a day or LESS on my pool. Occasionally I spend 5 minutes (very rarely). I spend 15 minutes once a week running the full set of FAS/DPD tests. I toss my robotic cleaner (Blue Diamond) in once a week to vacuum AND brush the pool. I RARELY put in even an hour per week on pool maintenance.
Yet my water is crystal clear, sanitary, sweet-smelling and soft on the skin all summer.
It is the result of knowledge learned here from others, experience of my own pool, and planning that takes place all year round. It is also always a continuous learning experience.
Hey Carl, you have a robotic cleaner and still vacumn and brush, well its just like an SWG... it produces chlorine but we still have to balance our water just like everyone else. But doesnt having a robotic cleaner make your pool maintenece life much easier... or you could have saved the $1000 on the robot and just hand vacumned exclusively. Wouldn't you consider that a luxury?
Good point, Canuck!
Ditto Canuck....
The $1200 Blue Diamond is justified even though it only gets used ONCE A WEEK. Yet a $700 SWG isn't but would be used DAILY, eliminating the need to lug all those jugs of bleach & recycling the empties.
I guess it depends on what a person wants.
I don't see the connection. I don't vacuum and brush--the robot does it. Vacuuming and brushing are at least an hour long job, every week, that is just plain hard work that, unless I want a work-out, I could do without (especially brushing). Besides, the robot not only does a better job, it acts like a super-filter, turning over the pool in 3-4 hours with DE level filtering.Quote:
Originally Posted by CanuckPool
The robot saves me lots of hard, sweaty work. An SWG would save me a few minutes of easy work a week.
THAT is the difference--saving me from a job I dislike versus saving me from a job I don't mind.
I KEEP saying this: There is nothing wrong with having an SWG if you want one. It's YOUR choice on what is a pain-in-the-neck job and what isn't. It's YOUR cost-benefit analysis.
And I can tell you: If I had to choose between a robotic cleaner and an SWG, then hands-down I'd take the cleaner.
As a techno geek with both a robot and a SWC, I'd side with Carl (even though I don't really see an argument here) that the Robot saves MASSIVE amounts of time and labor vs. the pouring bleach/SWC debate.
Labor and time aside, my Dolphin polishes the water to a quality far beyond what my sand filter with DE does. Conversley, Cl is Cl is Cl, so bleach vs. SWC doesn't show a step change difference in sanitation effectivness (efficiency, yes).
As everyone has already stated, if it makes sense for you, go for it!
ok, what about the argument... does having an SWG save the environment from the production and disposal of hundreds of bleach bottles and the manufacturing of bleach. I would think it helps eliminate one more chemical you have to store and move and pour into the pool.
Well, I can tell you that my chlorinating liquid bottles are reused since I pay a deposit for them and for the case (of 4) that they come in so there's no waste there (I return empty bottles to the store and get different bottles that are full -- I presume they take the empty bottles back to the manufacturer for rinsing and refilling). Standard bleach bottles are a different story and can be recycled, but that's not as efficient as direct reuse. As for the manufacturing, it's probably not much different doing that in a central facility as doing it in your home as far as energy used to generate the chlorine, but you are right that you would be helping the environment in terms of transportation energy usage in terms of hauling what is mostly water (sometimes the chlorine is delivered at higher strength and then somewhat diluted, but even so it's still mostly water).Quote:
Originally Posted by CanuckPool
If one is concerned with the environment, then the most effective expenditure would be using a pool cover. If having an automated (electric) cover would have you use the cover more frequently, then that would be worth it (that's what I have). The use of a cover significantly cuts down chlorine consumption -- my 16,000 gallon pool consumes less than 0.5 ppm FC per day during the summer. That probably cuts down my chlorine consumption by a factor of 4 or more. And when I get my IntelliFlo...well, we'll just see what happens to pump electric usage.
Richard
For about 7 months of the year, my SGW is disconnected (Canada), so lets say my cell is rated for 10,000 hours. My cell can sustain proper chlorination at a rate of 40% per hour on average. So in one day lets say the cell is on 9.6 hours (this is assuming you are running your pump 24/7) 9.6 x 31 days (month) = 297.6 hours per month of cell runtime x 4.5 months = 1339.20 hours a year, that gives me 7.4 years of cell life... so lets say for arguments sake it really doesnt last that long, so lets just take 1 year off its life. 6.5 years. So in 13 years it would have cost me 2 cells, about $2000. and I am sure in 6.5 more years the cost of cells might even come down a little. So lets see.
Amortized over 13 years it would cost me approx 153.86 per year to own an SWG, divide that by the 4.5 months I have my pool open, thats $34.19 a month. Ok, as stated in previous posts, there are electricity cost to run it, heck, I'll even round up to $40 per month, and yes there is salt costs and acid costs, but there is also costs associated with putting gas in your car to go and get bleach (I'm not even going to try and figure that cost out) Lets just assume your cost of gas vs. salt is a wash. I am not sure what the real cost of bleach over a month is, it appears to be anywhere from 8.80 to 16.80, I guess the bigger the pool the more the chlorine. Lets take the middle and go with $12.00. So 40.00 - 12.00 gives me $28.00. Now what about the days where you go away for a long weekend or vacation, what costs do you associate with having to have a neighbor pour the bleach in, or having a pool service do it. And what if they mess up, there are far more costs in bringing it back up to speed. Now, an SWG isnt foolproof, but it can save you from that neighbor that was suppose to check on your pool that long weekend but forgot and now it has become green. Lets talk real world here, not everyone can stay home the entire season and check on their pool everyday. I'll pay that $28 insurance, especially when my swimming season is very short.