Salt: Pool Math

[Mindflux]

I used PoolMath to calculate how much salt I need to get up to 3000 PPM.

According to PoolMath to go from 2400 to 3000 PPM I need 65 lbs for 13,000 gallons.

I added 40 lbs in the shallow end with the SWG set to 0% and brushed it toward the deep end and left the pumps run for a couple hours. I kicked on the SWG when I could no longer see any visible salt at the bottom and it's reporting I'm at 2600 PPM. According to PoolMath to go from 2400 PPM to 2600 PPM I need just 22 lbs of salt, but I added 40 lbs!

Is my mix just not homogenous yet or is poolmath broken or something? I don't want to add the other 15 lbs until I am sure of what's in my pool presently.

 

[JohnT]

You should always backup the readout of your SWCG with a test kit for your salt level.

13,000 gallons of water weighs just a bit over 100,000lbs, so you can estimate that every pound of salt you add adds 10ppm of salt to your water to check your math.

 

[Mindflux]

You should always backup the readout of your SWCG with a test kit for your salt level.

What good are the gadgets if you can't believe them? Hah!

 

[JohnT]

What good are the gadgets if you can't believe them? Hah!

They keep your blood pressure up!

 

[Xexys]

You really should let the salt disperse for 24 hours and let your pump run for that length of time too. After 24 hrs I would then click on the SWG and test with a good salt water test kit, like the Taylor K-1766, then check your SWG readout to confirm.

 

[Mindflux]

You really should let the salt disperse for 24 hours and let your pump run for that length of time too. After 24 hrs I would then click on the SWG and test with a good salt water test kit, like the Taylor K-1766, then check your SWG readout to confirm.

It seems everyone has a different method. At least I didn't dump it into the skimmer with the SWG running!


I fail to see how salt dissolved in 3 hours is different than salt dissolved in 24 hours. But I've got the SWG set back at zero for now to be safe.

 

[bdex]

Some on here will tell you that if it is close it really does not matter what the Taylor test says. I have the Taylor test kit and mine sits right at 3000 as per the kit. My SWG says 3100. It is happy and runs fine so I just deal with it. If you are they type that has to have everything exactly matchy matchy then you can test and re-calibrate your SWG to that number.

 

[Bama Rambler]

Most chemicals disperse throughout the water very rapidly (especially the liquid chemicals), but salt can take a while to completely disperse in the water even after it's apparently dissolved. That's the reason for the suggestion to wait 24 hours before turning on the swcg.

Also, most all swcg's don't actually test for salt. They extrapolate it from the conductivity of the water and some of them adjust for temp. As the cell components get scaled over their sensitivity goes down and thusly so does the salt reading. That's why it's suggested to get an independent salt test.

 

[Mindflux]

Also, most all swcg's don't actually test for salt. They extrapolate it from the conductivity of the water and some of them adjust for temp. As the cell components get scaled over their sensitivity goes down and thusly so does the salt reading. That's why it's suggested to get an independent salt test.

I tend to believe it when it's reporting low salt. I start getting some mustard algae type stuff on the walls and steps of the pool if I let it go too long. I imagine that would be because of low FC.

 

[RobbieH]

You should absolutely take action when the SWG says low salt. Regardless of the actual salt ppm in the pool, some SWGs will shut down or limit output when they think the salt is low. This is the case where you have to make the SWG happy.