SWCG Maintenance Question

[BigTallGuy]

I have a Compu-pool CPSC-24 SWCG. Last night I noticed the Low Salt Light was on. I thought this was odd as I added salt 3 months ago and should not be needing any more. I took a sample in and as I suspected my salt wat at 3500 PPM, which is perfect for this unit.

I did notice that there is a white build-up on the cell that is visible through the Clear blue plastic housing, that is pretty heavy on the head end of the cell where the wire connects.

I stupidly thought that self-cleaning meant self cleaning, and realize that I need to clean my cell, but would this cause the LOW-SALT light to come on, or do I have another problem?

[chem geek]

The low salt will come on whenever the conductivity of the water is reduced. This can come from a low salt level, but can also come from scale buildup on the plates. Even cells that auto-reverse polarity still need to be cleaned, just not as often.

Lower temperatures also lower conductivity, but many salt cells have temperature compensation for their sensor readings, though they will generally shut off when the temperature gets too low since the conductivity will be too low (from the low temperature) even when the salt level itself is OK.

[BigTallGuy]

Thanks for the response, once again, this is an awsome forum. Just as an observation, when my pool water was a balmy 42° F the SWCG still seemed to put out chlorine.

I did find a website that actually shows a step by step of how to clean the cell OF MY VERY MAKE AND MODEL. How lucky does one get?

I'll post the link if it is o.k.

[BigTallGuy]

Well, as always one thing leads to another. I disassembled and cleaned my cell by first picking and washing away most of the soft alkaline deposits, then used 4 cups of water and 1 cup of Muriatic acid solution and let is soak for 5 minutes, hosed the cell off and re-assembled the unit. When I started the system, the Low Salt light came back on. Frustrated, I took another sample of water to a different pool store and verified that my salt is 3500 PPM.

However, the Pool Store guy tells me that my Ph is off the chart like 8.2 or higher. I asked him to check it again and he did but he did something strange. After filling the tester with fresh sample water, he puts 3 drops of chlorine neutralizer into the test then the 5 drops of the #2 Red Solution, and whaddya know he's right, it was again off the chart. I asked him why he put three drops of the Chlorine Neutralizer in, and he says because your chlorine level is way high like 3.0 - 4.0 again almost off the chart. I thanked him and left.

When I got home, I tested the Ph myself first using ONE DROP Of Chlorine Neutralizer and 5 drops of #2 Red and got 7.4 Ph, a pretty Peach color. When I retested the second time using 3 drops of Chlorine Neutralizer and 5 drops of #2 Red, I got what he got over 8.2.

Sooooo, here is the burning question, Who's right? The instuctions that came with my cheap tester kit says one drop of #1 Solution which is the Chlorine Neutralizer, and 5 drops of #2 Red. Is using more Chlorine Neutralizer a little trick to "POOL STORE" a BIG TALL DUMB GUY?

Here is the rest of the story, when I got home two things happened, first I added a cup of acid, and the SWCG switched from Polarity One (where it had been running with the Low Salt light on) to Polarity 2 (which I assume is how the self cleaner works), AND THE LOW SALT LIGHT WENT OUT!!! ???? I am not complaining, just confused. Did the Self Cleaning thing "FIX" the problem, or could one polarity direction have an issue? Or, Maybe it is/was the Ph? Since very few of us are swimming anyway, I thought I'd keep the forum going with yet another series of questions.

Thanks, BTDG

[Poolsean]

It's possible that your cell may be worn down on one side, moreso than the other. If you consistently see that the low salt warning when you're in the same polarity direction, then that's probably what it is.
It may also be related to the power supply. In the course of polarity reversal, there is a physical relay that is activated to switch the electrical polarity. If this relay is bad, it may not be allowing a good electrical connection to read the salt properly (just a guess).

Not sure how to answer your Chlorine Neutralizer question though.

[BigTallGuy]

Thanks Sean,

I got into to the inner programming of the control unit and changed the self cleaning frequency from 12 hours of run time to every 4 hours of run time, and I plan to keep a close watch on the unit.

I am also concerned with the Ph testing issue. Like Richard said, there are a lot of factors, water temp, cell cleanliness, and I am sure Ph plays a big factor, or at least contributes to the conductivity of the water.

I really would like to get to the bottom of this Chlorine Neutralizer issue.

[chem geek]

Chlorine neutralizers that are simply sodium thiosulfate can increase the pH of the solution. So the better thing to do is to get a proper test kit that has special chlorine neutralizers built in using multiple types that offset each other in terms of pH effect. I don't understand why you aren't using the Taylor K-2006 kit after all of this time. You definitely get what you pay for. With this kit, you do not use the chlorine neutralizer -- you just add the 5 drops of indicator dye (with built-in neutralizer) and this should work up to an FC of around 10 ppm before you get significant interference.

[BigTallGuy]

O.K. I'm guilty as charged. Until now, I didn't spend the money for the Taylor Test kit because I (A) didn't think I needed it, and (B) hate to waste money.

For the sake of this discussion, for those that do own the test kits that have a bottle of chlorine neutralizer in them, is the practice of adding additional drops of chlorine neutralizer to compensate for higher chlorine levels legitimate or bogus?

Based upon your previous comment, my guess is, more is not better.

[chem geek]

Kits with a separate chlorine neutralizer that use them in the pH test are a half-baked attempt at making things work. More neutralizer is not better, especially when the chlorine level is < 5 ppm. Again, get a proper test kit. There is absolutely no excuse for it and I don't mean just the pH test. Without a FAS-DPD chlorine test it is impossible to do an accurate overnight chlorine loss test or even a 24-hour test to accurately determine chlorine demand nor is it possible to know if you have a Combined Chlorine (CC) problem with any reasonable degree of accuracy. And, of course, if you ever need to shock the pool, without a FAS-DPD kit you will be clueless as to the actual FC level (unless you significantly do dilution ratios for DPD for very rough accuracy).

[BigTallGuy]

Richard, Thanks for your response. I have seen just about every pool store that has tested my sample pull this stunt. I think this is one of their "Sell the Acid" tricks.

As a side note, I think I have an issue with my SWCG as when the unit switched back to Polarity 1, the low salt light came back on. I am trying to get a warranty claim going as it is only 8 months old.