Salt Water Pool Conversion

[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/Pro...uaPure-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.

[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.