New Pool, Added Salt, But Unexpetedly Low Initial Salt Readings

[packetfire]

I bought a small above-ground pool, 9 x 18 foot capacity 4545 gallons.
It has a sand filter, and I provisioned an SWG, so I added salt to the water, as follows:

4545 gallons
38178 pounds water @ 8.4 lbs/gallon
115 pounds salt
0.003012206 fractional salt/water by weight
3012 ppm

But not so fast - both the pool store (who tested with a strip) and my own salt-test strips ("AquaCheck" brand) read low.
Waaaay low. 3.8 on the strip scale, which equates to 1110 ppm

Where did my salt go? It all dissolved properly, an it was in sealed bags from the Morton Salt company, labeled as pool salt, so pure to the usual quality standards one would expect for a major name-brand.

The SWG is working, and the free chlorine level and total chlorine level are acceptable, and the pool LOOKS great, but this is only the first week. I cannot fathom where the salt went, and I hesitate to add more, for fear of inaccurate tests, resulting in an overloading the amount of salt in the water. It has not rained much, the pool was filled, and then salt added last week.

1) What should I trust here? My math, or the test strips?
2) How could I be so far off in terms of expectation vs test strip readings? I fear I am making some very basic error.

May I please buy a vowel?

 

[jblizzle]

Welcome to TFP!!!

Get the Taylor drop based salt test.
Your math (and the calculations done PoolMath which is easier) align. Should be up around 3000ppm.
Does the SWG report a salt reading or not? (add your pool details and equipment in your signature)

How good is the pools circulation? We has one report that all the salt water was stratified on the bottom of the pool because their circulation was so bad.

 

[packetfire]

The mystery was solved with a visit to a much, much better pool store, Leslie's Swimming Pool Supplies, who had an actual conductivity meter, and found the salt level to be exactly what I calculated it should be - 3000-3100 ppm.

So, the "LaMotte Insta-Test Salt Test Strips" are utter junk, and not to be trusted, and why the local pool store uses them is beyond me.

 

[Jimrahbe]

pf,

You just lucked out with your Leslie's test... Pool stores are the last place I would ever go to have my water tested.. Do it yourself and you can trust your results...

Thanks,

Jim R.

 

[packetfire]

A conductivity meter cannot lie, and is idiot-proof. Anyway, when you add x pounds of salt to y gallons of water, it does not take much math to figure out the parts per million salt, given that water can be estimated at 8.4 pounds per gallon.
And you KNOW how much salt you put in, and you KNOW it won't go anywhere once you do.

 

[kcindc]

Most SWGs state that they should be turned off when you add salt. I wait until the salt has been fully dissolved before turning the SWG back on. Sometimes it can take about and hour and half for adding one bag, or it could take a day if I have to add many bags of salt. It really depends on the temp of the water and how fast the water is circulating.

Can you add the details of your SWG? Most of us with SWG only add when the SWG says that the salt level is low. As long as the SWG is working and producing chlorine, who cares about the exact salt level?

Please add your pool details (including the SWG) , so we know how to help you. If we know the SWG, we can give you more accurate feedback.

If you are curious about your exact salt level, buy the drop test mentioned by jblizzle as pool store testing and those crappy strips are not accurate.