Adding Salt and determining pool volume

[drewhiggs]

Today is day 30 after water was added to new plaster, so I decided to add salt that was left by the pool school company. I originally thought my pool was around 15.4K gallons, but the salt test is telling me different.

After adding 240 pounds of salt and running the pump for several hours, my reading is between 4.6 and 4.8 which is around 1630 ppm.

According to the pentair salinity calculator, my pool volume is around 17.5k gallons. A 17.5K pool requires 493 pounds of salt. After adding 240 pounds of salt, I should be at 1670 ppm which is close to where I am.

When my pool was being filled, I read my water meter and added 500 gallons due to rainfall, but I didn't think I would be off 2,000 gallons.

Am I calculating this right or am I missing something? Is there an easier method to calculate pool volume by using chemicals?


Salt Strip

Salt Strip Chart

 

[mknauss]

I would wait a bit before adding any more salt. For one your SWCG will not run until your pool water is above about 55F so no real reason to rush it. Second salt is heavy and can sit in the deep end. Put your suction to full main drain if you have one. Brush the pool completely. Then test your salt level in a day or two.

 

[Jimrahbe]

Drew,

If you are relying on your IC40 to tell you the salt level, they are almost always way off when the water is less than 60 degrees.. Even when working, the tolerance is +/- 500 ppm.

It is best to use an actual salt test kit.. I use the Taylor K-1766... I NEVER believe what the cell says...

Thanks,

Jim R.

 

[drewhiggs]

I used the strips. I edited the original post with a hyperlink to a picture of the test strip.

I’ve turned off the IC40 and the pool water is at 59 degrees. I brushed the entire pool after adding the salt, but I’ll take your advice and brush again before work in the morning.

It did rain the entire time the pool was filling, so it’s possible I’m off on my calculations. I set a 5 gallon bucket of water out during the fill. After the pool finished filling, I had 2” of rain in the bucket.

 

[drewhiggs]

I checked again today and the readings are almost identical.

I'm using the AquaChek test strips that I bought from tftestkits.net, so I'm assuming these are accurate.

It looks like I need to adjust my pool volume for my Pool Math calculations.