Salt Reading Error?

[sb2323]

Hi, thanks for reading. We have an Aquarite control panel. It had been showing salt at 3000 ppm up to a couple days ago when I put it into "service" mode so I could run the pump 24/7 (trying to clear up black algae). Therefore, the salt readings were not displayed. We shocked the pool both days it was in service mode. Today I turned the service mode off briefly and the salt read 200 ppm. Immediately dumped 7 40-lb. bags of salt in the water. It's now been 7 hours and the salt is reading 0 ppm. Is this possible? Or is something wrong with my readings? I checked the system and from my very limited knowledge it seems to be operating properly. I ordered one of Ben's PS234s test kits today, and will test the water as soon as the kit arrives. I do not know what any of my other levels are, other than AquaRite at 50%. Do I need to have a service call, or somehow test the water now before the test kit arrives? If so, should I buy the strips or bring the water to Leslie's for testing? I've never brought water in for testing--how should the sample be taken, and what should I put it in? Thanks in advance for any advice.

[Rockman59]

sb2323 said: It had been showing salt at 3000 ppm
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Seems most SWG digital salt readings tend to bounce around a bit...but not from 3000ppm down to where your low readings were. Take a water sample to a reputable pool store and have it tested. I'll bet your readings will be way high because of the added salt you put in the pool. I have been told that the only way salt levels will go down in a pool is by dilution. That could happen by getting a lot of rain water in the pool.....or by adding fresh water to your pool with a hose. Other than that the salt levels will stay the same.

[Poolsean]

Me thinks you better have your installer check out the system. It's possible that if your cell is scaled up or some blockage on the cell, it will give you a false reading. The cell is attached with unions so you can remove it and visually inspect it. If you're able to see the blade (you may try a flash light on the opposite end, or if there there is some blockage on the plastic grid infront of the cell, these can also indicate no salt.
Or it may be something else worse.
First things first though and it's worth checking the easier stuff first.

[sb2323]

Thanks for the advice! I took a water sample to the pool store and my salt is registering at 6100, chlorine level 0. I drained half the pool and replaced the cell. Hopefully that will solve my problem.

[Poolsean]

This high salt level will definately affect your salt display.
Did you by chance happen to check the condition of the cell? Again, the cell condition is what determines what the salt display shows.

[sb2323]

Our salt reading went from 2800 down to around 2200 within a couple weeks. We added another bag of salt. It went back up to around 2700 and we added another bag of salt, bringing it up to 3000. Shortly after, we noticed the black algae. I read that the algae can affect chlorine production and I thought maybe our "salt" reading was actually measuring "chlorine" because the salt then declined within a couple days to 200. At that time I consulted the manual, which indicated I should inspect the cell and clean it if necessary. We were so clueless, though, we thought the plug that goes into the wall unit was the "cell", not the big white cannister. We pulled it out and dutifully checked it, and saw nothing wrong. Shortly afterwards the salt level suddenly dropped to 200. I then added 7 bags of salt (thinking the algae was still to blame) and within a day it dropped down to 0 and stayed at 0 for a week. Our control panel this entire time indicated "low salt", not "high salt". The cell is approximately 6 years old, which I think is a fairly normal life span?

Anyway, I just examined the old cell and it does look like it has some calcium buildup but I'm not sure what would be considered excessive. It's just a few crystals, not blocking the filter or anything. I didn't look at the inside of the new one before I installed it so I'm not sure what it's supposed to look like.

I do hope that I didn't just go out and spend $500 for a new cell that I didn't really need. But at least thanks to the helpful responses here I'm learning a lot more about my pool system and how to maintain it properly. I just wish it didn't have to be such a frustrating and expensive way to learn it. Thanks for your responses, and any additional insights would be appreciated.

[Rockman59]

sb2323 said: We pulled it out and dutifully checked it, and saw nothing wrong. Shortly afterwards the salt level suddenly dropped to 200. I then added 7 bags of salt (thinking the algae was still to blame) and within a day it dropped down to 0 and stayed at 0 for a week. Our control panel this entire time indicated "low salt", not "high salt". The cell is approximately 6 years old, which I think is a fairly normal life span?
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The algae won't affect your salt readings. I would bet anything that your cell is bad. 6 years is a long time for a cell to last....of course it all depends on how many hours it has on it. Have you taken a salt reading with the salt test strips that are available? They are not the most precise measurements but it will show you a ball park number.