Downsides to salt pools

[Davenj]

Had the pool vinyl IG for about 18 months, SWCG. Kool Deck, haven't noticed anything with that. The SS railing had a white gritty paste/slurry in the aluminum mounts in the deck. Noticed it when I removed them for the winter. Any suggestions for next season.

Dave

[chem geek]

Dave,

My guess is that the white paste is salt. If these mounts were in the deck, then splashed water could go into the mounts and evaporation would get rid of the water leaving the salts that are in the pool. Multiple cycles of water entry and evaporation would leave more and more salt. For an SWG pool, this would mostly be sodium chloride, but there would also be some calcium chloride as well (I assume that the bicarbonate would outgas with evaporation [EDIT] though you could have some solid sodium bicarbonate as well [END-EDIT]) and some sodium cyanurate. The next time this happens, or if the paste is still there, you can test it by putting a little in distilled water (or tap water, if you test the tap water separately) and then 1) see if the paste dissolves in water and 2) measure the salt (chloride) level. If it's high, then the paste is likely to be salt. You could also measure the CYA level to see if I'm right about the sodium cyanurate.

As for what to do, there doesn't seem like much except putting some sort of waterproof caulking around the top of the mount against the stainless steel railing. You could probably very easily remove the caulking when you want to remove the railing at the end of the swim season. I'm not much of a mechnical guy so others would likely have better suggestions.

Richard

[Phillbo]

I've yet to have my system a full season so my 'down side' is limited. So far, its been all up side similar to:

• Less maintenance. Chlorine added automaticaly. No need to buy chlorine, physically carry it home, and add it regularly (possibly daily).
• Lower possibility of developing algae, though this may be more related to the continual addition of concentrated chlorine rather than the SWG, per se.
• Less burning of eyes. Salt in water is closer to salinity of human tears.
• Water feels silkier.


My cons are limited as well:

-The up front cost was well within my comfort zone.
-I add a little more acid than I use to but thats a minor negative.
-I have no metal ladders, rails or heat exchangers in my pool.
-I hose off my pool deck and patio weekly during the swim season (did so before installing the SWCG) so I see no build up.


basically, So far, so good.

[Davenj]

Richard,
I'll test the for salt in the paste next season. My CYA ran 50ppm. Good suggestion about the chaulk. I will try some DucSeal, it stays plyable and will be easy to remove.
Thanks
Dave

[chem geek]

Well so far, the two reports of corrosion in salt (SWG) pools on this forum have had possible alternative explanations other than the increased salinity. In this thread, it appears that the corrosion of stainless steel could be from the high effective chlorine levels due to not using CYA, though the very rapid speed of this corrosion may be due to multiple factors (including salinity) combined together. In this thread it appears that the quality of limestone is the critical factor and that salinity may play a far lesser role in this case.

My gut feel on this is that different factors affect corrosion and can combine together as well. Therefore, blaming a single factor for corrosion is sometimes just used as an excuse. That does not mean that there are not situations where salinity causes greater corrosion, but that it may be getting blamed as the sole or primary factor in some situations where this may not be the case.

Please continue to give us your stories and facts about corrosion you experience, as only a large number of cases will allow us to sort all of this out.

Richard

[nater]

My experience:

Experience with pool prior to SWC: 18 months
Time with SWC: 12 months
Salt Level: 3200 ppm
FC levels (Ave): 4-6
pH levels: 7.2-7.6
TA (Ave) 120 through late this summer, now at 80 to reduce pH rise
CH: 300
CYA: 120 to current level of 70
Temp range: Winter 40-50 deg, summer 78-86 deg
Pool type: Vinyl Inground
Metal Elements: Stainless Ladder in deep end, light ring in deep end, handle on skimmer lid, plates is SWC cell. (No Heater, no copper, etc).

Observations:
After reading the threads about possible corrosion due to SWC operation, I took a very good look at my pool and equipment.
-I see absolutely no staining or degredation of the concrete at the pool exit points.
-I see some corrosion of my light ring. This was a pre-existing condition and most likely due to low pH (<6.8) resulting from puck usage during the off season (and before finding this forum ). It has not increased during the year of SWC operation.
-I rigged a kitchen cabinet pull handle to my skimmer lid for easier removal. The screws inderneath the lid have corroded badly. They are NOT stainless. This is not unexpected as I usually add salt to the skimmer when needed. No surprises here.

I believe that prior to purchasing such a system, the buyer owes it to themselves to do a lot of homework. Ignorance is no excuse, and unfourtunately the majority of people in this industry seem to have an aboundance of it. (Anybody that's been "Pool Stored" knows of what I speak)

A SWC system is not a magic bullet. As with any other technology in any other industry, education and awareness of the system's pros and cons are required to make a good descision. For me, it is an absolute perfect fit. For others it may not be the best solution. This is where the "Industry" fails and salt chlorinators in general get blamed for problems resulting in poor execution.

I hope Waste chimes in on this subject. He's got loads of experience with various setups and I'm interested to know his thoughts.

[Waterworks]

We've been installing SWC's in residential (40+), and commercial (around 10) applications for a few years now. Most of our residential jobs have concrete decking. I have heard no complaints of pitting concrete and not one case of ladder or copper-nickel heat pump corroding. I have one customer in particular with cantilever limestone coping that has noticed no pitting at all, at either steps or the rest of the pool. Another customer has flagstone coping and also noticed no damage after one season. Our commercial jobs are all full-tile and we haven't had any problem with pitted grout on the tile or deck.
I'm going to go over these problems with my service men before the upcoming season, and get them to keep a closer eye on ladders and decking materials. Once I hear from them, I will update in this topic.

Update, I just remembered one issue in a commercial setting. After a few weeks of the pool being open there was staining on the light ring, which transferred a rust stain onto the returns and also the stainless steel heat exchanger corroded to the point that it wouldnt heat at all. The problem was initially blamed on the "corrosive salt". I took a water sample back to my shop and tested the chlorine to be 42 ppm. I think that a lot of the pitting and corrosion issues could be related to high chlorine levels. Since many ppl use dpd test kits, they don't notice that their chlorine level rises way above the norm. Also, since the person doesn't have to add their own chlorine they have no idea how high it can get.

Brad
Waterworks Pools