Rise in Salt.

Apr 6, 2015
15
Surprise, AZ
#1
I believe I know the answer to this question, but it is digging at the back of my brain, so I thought I would just ask. Is there any way that the salt levels can be increased WITHOUT adding any salt? For some reason my level went from 4000 ppm on March 6th to 4700 on April 3rd. I talked with the pool cleaning service to confirm that no salt was added by them, but don't know if it was lip service.
 

pooldv

Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
Aug 10, 2012
24,993
DFW, TX
#3
Yes. Lots of things add salt to your pool. All types of chlorine, muriatic acid, tap water and humans all add salt to your pool.
 
OP
OP
L
Apr 6, 2015
15
Surprise, AZ
#4
pooldv..... Did not consider the human factor, as this pool is in a retirement community and the Snow Birds are here.........Joyfulnoise...... 3 diferent types of tests, pool store, test strips (by me) and SaltDip Digital Tester (by pool cleaners).
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
14,667
Tucson, AZ
#5
Ok, this is likely a measurement problem. To get a true, 700ppm increase in salt would require 187lbs of salt added to a 32,000 gallon pool. This is not a chemical issue. This is a measurement issue.

Is the pool store using a drop-based titration test? Unlikely, they usually use strips. Strips are highly unreliable and often have an error of +/-400ppm when brand new. They age and they go bad very easily.

Digital testers are electrical conductivity meters essentially reading TDS. Unless the tester is specifically calibrated with a known standard sodium chloride solution or standard TDS solution, they can easily lose calibration. Also, an electronic meter is going to detect ALL forms of conductive ion species including the calcium ions in your pool. So unless you have accurate and independent measures of all other components of the TDS, teasing out the salt concentration is exceedingly difficult.

You need to get a Taylor K-1766 salt test kit. It measures chloride ions (Cl-) directly and is an EXACT test. There are no interferences from other ions. It has a standard +/-200ppm tolerance for a 10mL water sample but can also be made more precise simply by testing a larger volume of water (a 25mL sample has a +/-80ppm tolerance). This is the ONLY test that I recommend for salt level measurements. Everything else is a proxy test that measures "something else" and infers the salt level from there. Even your SWGs do not accurately measure salt levels.

Do yourself a favor and ditch all the other tests and purchase a K-1766. It's roughly $25 and you'll get 50 to 100 tests out of it before any of the reagents expire; that's more tests than you ever really need.
 

Divin Dave

TFP Expert
LifeTime Supporter
Oct 2, 2013
5,192
Longview, Texas
#6
I totally agree with Matt. Strips are notoriously erroneous and the digital ones are too dependent on other things in the water which is difficult to account for. Do your self a favor and get a K1766, you'll be glad you did.

Ok, this is likely a measurement problem. To get a true, 700ppm increase in salt would require 187lbs of salt added to a 32,000 gallon pool. This is not a chemical issue. This is a measurement issue.

Is the pool store using a drop-based titration test? Unlikely, they usually use strips. Strips are highly unreliable and often have an error of +/-400ppm when brand new. They age and they go bad very easily.

Digital testers are electrical conductivity meters essentially reading TDS. Unless the tester is specifically calibrated with a known standard sodium chloride solution or standard TDS solution, they can easily lose calibration. Also, an electronic meter is going to detect ALL forms of conductive ion species including the calcium ions in your pool. So unless you have accurate and independent measures of all other components of the TDS, teasing out the salt concentration is exceedingly difficult.

You need to get a Taylor K-1766 salt test kit. It measures chloride ions (Cl-) directly and is an EXACT test. There are no interferences from other ions. It has a standard +/-200ppm tolerance for a 10mL water sample but can also be made more precise simply by testing a larger volume of water (a 25mL sample has a +/-80ppm tolerance). This is the ONLY test that I recommend for salt level measurements. Everything else is a proxy test that measures "something else" and infers the salt level from there. Even your SWGs do not accurately measure salt levels.

Do yourself a favor and ditch all the other tests and purchase a K-1766. It's roughly $25 and you'll get 50 to 100 tests out of it before any of the reagents expire; that's more tests than you ever really need.
 
OP
OP
L
Apr 6, 2015
15
Surprise, AZ
#7
While I do agree that the Taylor K-1766 test kit, that I recieved this morning, is a more acurate testing method, the level of salt is the same as the other 3 tests, 4800ppm. I still can not figure how the water had a rise of 700 to 800ppm in salt, in 1 month. Yes, the bather load is more, but that is alot of sweat from these Snow Birds, coupled with the fact that filter is backwashed 5 out of 7 days. Other readings are great, FC 7.8, CC .0, Ph 7.3, Alk 80, Cal Hardness 160 and Cya 40 and yes I use Fas-DPD.
 

ping

TFP Expert
LifeTime Supporter
Jun 24, 2011
2,939
Long Beach, CA
#8
With all that backwashing I would say someone added salt and didn't admit it. If the SWG is happy then it shouldn't take too long for it to be lowered.

Get a list of all the chems that the service is adding, how often, and the approximate amount of each chem.