Salt Water Pool Conversion

[jskins2000]

New to the forum and just bought a house that came with a salt water pool. I have a a Zodiac Clearwater Lm2-24 system and it has been nothing but a headache. At this point I am thinking about converting this to a standard chlorine pool. Is this possible and what does it entail?
I cannot seem to get this pool balanced. It calls for 4000ppm of salt. It was at 3500 about 10 days ago. I added a 40 lb bag, got the water tested. Still at 3500. Long story short I put 5 full bags of pool salt and it is still only at 3900. This is a 10,000 gallon play pool. I have not back washed, there is no leak so why are the salt levels not rising?
Because there is no salt every two or three days I am dumping 2 bags of burnout shock and half gallon of acid. Everytime I go back to get water tested, its the same; add salt, add acid and shock. I cleaned the cell had the pool inspected and everything seems fine.
Is there anything I am missing? And can I just by-pass the salt cell and make this a chlorine pool?

[aylad]

Hi, and welcome to the forum!!

Yes, you can bypass the salt cell--a salt pool IS a chlorine pool--the difference being that with a SWCG, the chlorine is generated from the salt that's in the water, rather than added manually. The salt will stay in the pool, but that's not a problem--in fact, some of our members add salt to their water just because they like the "feel" of the water. Over time it will dilute, but probably won't ever go away completely unless you drain and refill sometime in the future.

You'll have to be consistent about your testing, though, because with a non-SWCG pool you'll need to add chlorine most every day. So make sure you have a good test kit (we like the K-2006 at the Amazon link in my sig).

[jskins2000]

Thanks. Any idea why the salt levels will not raise as expected? So far 5 bags of professional grade pool salt only raised salt levels 400. It's a 10k gallon pool.

[PoolDoc]

(4) 40# bags of regular salt -- regardless of grade -- will raise the salinity level of a 10,000 gallon pool 160 x 12 or 1920 ppm (NaCl). I checked this against Zodiac's own manuals, just to make sure of 'apples-to-apples' measurement. (http://www.zodiacpoolsystems.com/Products/Water-Sanitizers/AquaPure-Ei.aspx -- your unit is discontinued).

How are you measuring your salt level? If it's from a readout on that unit, then there's a sensor or calibration problem.

BTW, *if* you have an accurate chlorine test (eg, Taylor K2006 or other DPD-FAS kit), you can turn on the SWCG, and collect samples from just in front of the pool return, and compare them to water collected from just in front of the skimmer (should NOT be the same place!). If the return water is significantly higher in chlorine than the outflow (skimmer) water . . . your SWCG is working to at least some degree.

[jskins2000]

Yes that is what I presumed, but it has not raised. I am at a lost as to why it is not raising as expected. Does the SWCG have to be turned off for a few hours after I pour salt in?

To test my water I am run a dip stick test. Then I take the water sample to a pool store (tried two places for reliability). Each time the salt levels come out consistently low and within 100 ppm of my dip stick test. After the last bag was added, the "add salt" light went off for the first time on my sensor unit - however, that was short lived. After an hour the "add salt" light came back on. Pool store and dip stick confirmed 3900 PPM.

Great tip on the dual chlorine test. I will test at the return and at the skimmer to see if there is a difference.

[PoolDoc]

Ok. Possibilities are limited.

#1 - You added less salt than you thought, because they weren't 40# bags OR were diluted with something.
#2 - Your 'guess strips' were off . . . and so were the pool stores' strips.
#3 - Your pool has more gallons than you thought.
#4 - You're leaking and replacing a LOT of water.

I can't think of any others. If you add 160# of salt to 10,000 gallons of water, you are going to increase salinity by nearly 2000 ppm, every day of the year, everywhere in the world.

[waterbear]

a couple of thoughts:
Does your pool have an autofill and an overflow? A malfunctioning autofill can cause what you describe.

salt levels move with down CYA levels since they are both only lost by splashout, backwashing, and leaks.. Have you checked CYA to see if it is decreasing over time?

If you are using salt test strips (AquaChek) they take a full 10 minutes to develop. Most pool stores do not wait that long and the instructions on the bottle are not that clear (I got the 10 minute time from a tech note on the Hach/AquaChek website if anyone is interested in my source). If you do not wait long enough the strip, which is really a titrator, will read low.

As far as the low salt light on your unit...Your unit is reading conductivity, which is affected by more than just the level of salt in the water. Temperature, the age of the cell, the cleanliness of the cell, TDS, etc. all come into play. Chemical salt tests are tests for chloride ions (whether they are strips or titrations aka drop count tests). The chloride ion level in the water does not always correlate to the conductivity of the water. As cells age they will act like the salt is low even when it is not. Handheld electronic salt meters that some poolstores use also work by measuring conductivity. They range from very accurate if they are kept calibrated to so bad that you can get a better idea by tasting how salty the water is. My experience has been that MyronL and Oakton/Eutech meters (often rebranded as Goldline) are dependable if kept calibrated but if the store is using someting else I would not trust the results.

Finally, if you and the pool store are all testing with strips I would suspect a bad batch. Hach/AquaChek recently had a bad batch of strips that they documented on their website. (http://www.aquachek.com/servicepros/technical_article.asp?id=13)

[jskins2000]

First and foremost, thank you all for your help. I am glad I joined this forum.

PoolDoc -
After you said "you are leaking water" I went out to the side and sure enough there was water coming out... I have no clue how long this has been going on, because I walk by that area often and have never seen water coming out before. Which brings in a whole new issue. When the pump is running I can see through the window of the backwash pipe that clear water running through it. Keep in mind the backwash valve is down and in the locked position. So why would water be escaping through here.

Waterbear -
My CYA is going down as well, which is probably explained by the above. The autofill is working properly. I replaced it when i moved in and it was turing / off and on as expected.

[PoolDoc]

Ah-h-h. The downside of autofill units!

I think you need to fix the leak, get fresh test strips, re-dose with salt . . . and try again.

[jskins2000]

ok thanks... now I need to see why and where it is leaking.

Does this forum give advice on beer to soothe frustration?

[waterbear]

Ah-h-h. The downside of autofill units!

I think you need to fix the leak, get fresh test strips, re-dose with salt . . . and try again.

And don't forget to get the CYA back up where it belongs (for you unit that would be 100 ppm. It is best to have the CYA at the maximum of the recommended range for technical reasons (and with your autofill and backwashing filter it can even be as high as 120 ppm as long as you maintain the FC at 5% of the current CYa level so you will need to test on a regular basis with a good test kit. I strongly recommend the Taylor K-2006. Don't get a K-2005 even though it is slightly less expensive.)
I would also look into disabling the autofill. IMHO, they create more problems then they cure. One of the biggest problems is that they mask leaks until the water bill comes in!:eek:

[jskins2000]

Yeah I am nervous about the upcoming water bill. You said, "IMHO, they create more problems then they cure." What other problems does an autofill create besides masking a leak?

[waterbear]

Yeah I am nervous about the upcoming water bill. You said, "IMHO, they create more problems then they cure." What other problems does an autofill create besides masking a leak?

Isnt that enough? :eek::eek::eek:
Seriously, since they are constantly adding water and most have an oveflow also (as a safeguard for when they malfunction and don't shut off--notice I said when and not if!) then it means that your chemical levels might (will) mot be as stable as a pool without one. Scenerio, 4 or 5 people in pool splashing around, water level rises and water drains out overflow, autofill adds more water, salt and CYA just went down, repeat daily. IMHO, this makes maintenance of a salt pool much harder since you need to watch the salt, CYA, and borate if you use it (highly recommended btw) than without the autofill.

[PoolDoc]

Shorter version: auto-fill units hide problems you need to know about, like leaks, and create problems you don't know about, like the chemical issues Waterbear mentioned.

Ben