Salt water pool - pros & cons

[Expresspete]

Has anyone changed from a freshwater (chlorinated) pool to a salt water pool? If so, would anyone be kind enough to tell me the advantages or disadvantages in doing so please and do you use the same chemicals to keep it healthy or is it more expensive to look after?
Thank you in advance, Pete

[PolemIan]

We have had a SWP from day 1, so in our 9th summer. The initial cost of the chlorine generator is quite higher but obviously you then save on the cost of chlorine tablets. You’re effectively paying for (most of) your CL up front. Things to consider and decide if they are pros or cons:

- the water definitely feels more pleasant to the skin than the pool in our other place
- we do not use it all year around. The cell life is around 5000 hours so I don’t bother using it over the winter and just add tablets for background chlorine when the bathing load is effectively zero. Last year I turned it off in October, and for various reasons have only turned it on again a couple of weeks ago. I use 24 cl tabs in that period.
- the recommended CYA levels are a bit higher for a SWP as the chlorine you produce is unstablised. So use of tablets at start of the season, or CYA granules if you can get them, is advised to build up CYA to the recommended levels.
- the cells are not cheap to replace, ours was c€500
- we also had to replace the control unit when damaged by a power surge
- we also don’t use it when we have the solar cover in use. On our unit you can set the output level for chlorine production, and even at its lowest level, 10%, the chlorine will quickly build up to a higher level than is recommended as the cover virtually eliminates the CL being burnt off by the sun
- the chlorine is basically 100% pure, so less additives, than with tablets
- you need to keep an eye on calcium levels and once a year at least check the cell for scale build up as this significantly impacts the effectiveness of the cell. We use No More Scale to help keep this down
- from memory I’ve just started my 3rd bucket of tablets in 9 summers. Not sure how that compares
- I probably use 1 or 2 bags of salt per year to maintain the recommended salt PPM levels, but then I probably backwash less than most people as we have a pre filter - obviously when you dump water and top up back to the same level with fresh, you lower the salt PPM reading
- you still need to clean the pool regularly and maintain proper PH balance etc. Anyone who tells you otherwise is talking tosh.

If we were start again, would we go down this route again? Yes, but ideally I’d go for a unit that you can set target CL level. No idea if such a product exists as I’ve not needed to look into it, perhaps next time a new cell is needed, but I imagine that would come at a significant premium.

My comments above probably make it sound more complicated than it is, it’s just a case of adapting and I’ve obviously learned a lot as time has passed.

Hope this helps.

Ian

[Expresspete]

Thank you for your response Ian, it’s very much appreciated. I’ve just been quoted €1,150 (incl vat) to change my system from chlorine fresh water to a Salt Water Pool. I guess I also wanted to know about the maintenance etc as I’m having trouble with the cya (my fault as I’m using tric tabs at the moment instead of cal hypo). I have been warned to expect corrosion damage due to salt use by other people (who do not have a swp) but don’t know how much or how often to expect it. I use a digital test meter and a pool robot to keep the pool as hygienic as possible and I run the pump 12 hours a day because we have net metering. So I wondered if there is anything else (different) that I would have to do. We quite like the idea of an swp but before we take the plunge (sorry) I wanted to glean as much factual information as possible.
Thanks once again, Pete

[PolemIan]

Never knowingly had an issue with corrosion.

Ian

[Expresspete]

Thanks again Ian

[Kili01]

My late husband and I had our previously chlorinated pool converted to a salt water system with of course an SWC. ours was Australian in manufacture. We loved it, the water was so soft, we were told that the salt content should be low. The water should be no more salty than a baby's tears. We were also told that for a family pool with limited use (as ours was) we should not run the pool pump for more that 4-6 hours a day. We ran ours in two sessions, morning and evening. Running a pool pump for long hours in the sun, depletes the pool of chlorine and also causes extra wear & tear on the pump. Which is expensive to replace. Using less salt also means very little corrosion, Ny husband used to test the pool water regularly.
Would always reccomend using salt chlorination if the pool has fairly light use,

[PolemIan]

Dee, agree with your views on the water feel. At the correct PPM the salt level is approx 1/3 of a human tear (c9000PPM) which in itself is about 1/4 of seawater (c35000PPM).

The advice you were given about not running the pump for long hours in the sun depleting chlorine is a little odd. It’s the sun that burns off the chlorine not the water circulating. If the pump is not running, it’s not circulating through the chlorine generator, and zero chlorine will be produced and the chlorine levels will then drop rapidly in strong daytime sunlight - unless CYA is really high which is not necessarily a good thing. Too high and the effectiveness of the chlorine is reduced regardless of how it’s added to the pool. I’ve seen figures suggesting high levels of UV like we get here for a good chunk of the year can deplete chlorine by as much as 90% in 2 hours.

What does the comment about using less salt mean? The amount of salt in the water is fixed regardless of circulation and will only change if water is pumped out via backwashing and replaced with fresh non salty water.

Pete - the generator normally has a salt level warning system with some form of indicator, in our case:

Green for in ideal range - 2500 - 3500PPM
Amber low salt warning between 2000-2400
Red - add salt light at 1900ppm and below

If the pump is not running or the flow is insufficient we also get a Red flow warning light and the cell will shut down. There’s also a boost function which automatically slams it to 100% output if needed, never needed to use it.

I recently added 20kg which took it from 2800 -3200PPM in a 8x4 pool - €6.35 from our village shop. Last time the pool was fully drained and refilled 6 bags took it from zero to 3700PPM, slightly high but not far off the top end of ideal range.

Ian

[MikeH]

Very interesting discussion, folks; thanks.

I'm seriously considering switching my pool to SW, it having been ordinarily chlorinated for 12 years.

What's the advice on how long to run the pump and at what time of day?

Is it valid to presume that the flexible pipes (serving skimmers, jets bottom drain) would be less at risk of chlorine attack than when using CL tablets?

[Expresspete]

I have a vinyl liner, is it true this erodes with a SWP? Also, if a cell lasts 3-5 years, does anyone know the approximate price of a new one? Thank you everyone for your advice. I now have some serious thinking to do!

[daveg]

A friend of mine has been quoted €800 for a new cell...

[Dominic]

According to Ian's original post it costs €500 to replace.

I had always thought that a salt water pool meant that you didn't have to use chlorine. Learn something new every day.

[PolemIan]

According to Ian's original post it costs €500 to replace.

I had always thought that a salt water pool meant that you didn't have to use chlorine. Learn something new every day.

If you just have a salt water pool you just have a salty pool. The SWP has a cell with metal blades, titanium I think, that passes a current through it, magic happens and the chemical reaction with salt causes pure chlorine in the form of gas to be produced and circulated around the pool, the salt then returns back to its original form which is why you only have to add salt if you drain / backwash the pool and add fresh so eventually you’ll dilute the salt PPM to the point where a bit more salt is added.

Last cell was €500 and a PIA to source as we were bang in the middle of Covid in 2020. That was for Pool Pilot AutoPilot SoftTouch, not sure of other brands prices.

Never heard of any liner damage, ours is 2 years old when we switched from tiled to liner and looks like was fitted yesterday.

Ian

[Dominic]

I wonder where all the sodium goes?

[PolemIan]

Never knowingly had an issue with corrosion.

Ian

Autopilot advice corrosion can occur above 6000 PPM - almost double the recommended max PPM. If that ever happened, dump water and top up.

[PolemIan]

I wonder where all the sodium goes?

The salt? Ultimately nowhere, you never ‘use it up’ (unless you pump out water and replace with fresh). My chemistry is not great but after the salt is converted to chlorine by electrolysis or some such wizardry, I believe it’s then converted back to its original form by UV light. Which presumably is why they recommended to keep it running and maintain a slightly higher range of CYA.

Ian

[WHL]

I don't like the smell of chlorin, does a salt water pool still have this smell?

[AlanGW]

I have a 5m x 10m pool with Roman steps containing 90 cubic meters of water. 20 years ago I opted for a salt chlorinator and on the recommendation of pool company opted for one designed for 150 cubic meters to cope with the high summer temperatures. I was meticulous with maintaining the correct saline level and cleaned the cell every one to two months (rubber gloves on, 1 part hydrochloride acid to 4 parts water, remembering acid to water) In the summer months when the water temperature rose above 28 degrees, more chlorine needed to be added as the system couldn’t cope. Every 2 years a new cell was required at £C 400 as it was then. After five years, I removed the system as did 3 others in the immediate vicinity.
It proved a lot of extra work, especially cleaning around the waterline where salt would become encrusted after strong wind and I was still using a lot of extra chlorine.

[PolemIan]

I don't like the smell of chlorin, does a salt water pool still have this smell?

It depends on how well maintained the pool is as how heavily used it it.

From chemical safety facts.org;
“Pool smell is not due to chlorine, but to chloramines, chemical compounds that can form in pool water. Chloramines result from the combination of chlorine disinfectants and the perspiration, cosmetics, and urine that enter pools on the bodies of swimmers.”

Logically, this would be the same regardless of if your chlorine is powdered, tablet or generated by a SWC.

Ian

[PolemIan]

Alan, we’ve had a very different experience. Clean the cell once a year - the same way as you but mostly these days the addition of No More Scale keeps this down and last month it just took a couple of mins with the pressure washer to blast away any build up of scale on the cell. Definitely never had any salt on the waterline. The only thing similar would be the small pools of water that splash into the top of the solar cover when opened and closed - which then evaporates to leave the salt behind.

Ian