Adding Salt for the first time

[RobertFlagg]

I looked at the manual for the SWG IC40. Am I reading it right that I need 600 pounds of salt for a 20k pool?

 

[RobertFlagg]

Here is a cut sheet from the manual.

 

[Brett S]

According to poolmath 600 pounds of salt in a 20,000 gallon pool will raise the salinity by about 3585ppm. However, unless this is a new pool that was just filled you don’t want to blindly add salt. Chlorine and some of the other chemicals that we use will also add salt to the pool, so a pool that has been in use for a while will likely have a significant amount of salt already in the water. If you just assume that there is no salt in your water you will likely overshoot your target and need to partially drain and refill the pool to get the salt level back down.

Get a good test kit like the Taylor 1766 (don’t rely on strips) and check the salt level first, then determine how much salt you need to add.

 

[Dirk]

I just plugged in a 20000 gallon pool into Pool Math and got 500lbs to get to 3000 salt water. This is how I would do it (and I own an IC40, so this is how I did do it). Salt can accumulate over time in your pool. It doesn't evaporate. So I wanted to lengthen the amount of time before I would have to exchange water when the salt gets too high. So I figured I'd add as little salt to begin with as possible. Here's how. First, buy a good salt test kit (NOT strips). You have to know how much salt is already in your water before you can calculate how much to add, otherwise you can overshoot. Once you have your existing salt number, then use Pool Math to calculate how much salt to add. Target about 2800 for salt, and then put in about 80% of what Pool Math says to. There are a lot of variables that can cause you to overshoot, better to sneak up to your target number. For example, you say 20000 gals, maybe it's not. Mix it in good, let the pool circulate for a couple of days. Test your salt level. Repeat as needed to get up to about 2800. Be sure to wait a few days after the last addition before you turn on the SWG. Be sure to wait a few days after the last addition before you turn on the SWG. Yep, said it twice. It's important. See if the SWG will make chlorine. Repeat this process, always being sure to wait a couple days between adding salt and turning on the SWG, until the SWG works. Ignore what Pentair says about minimum salt.* Ignore the salt test results.* All you care about is that the SWG is making chlorine. Maybe add a half a bag just so that you're not scraping the bottom of the IC40's minimum salt requirement. This way, you have a functioning SWG at the lowest salt level it'll work. That will give you a little extra leeway before you have to exchange water as the salt builds up over time.

* I'm not actually suggesting you ignore the test or Pentair's instructions. Here's what's really going on. The internal mechanism in an IC40 that measures the salt content is notoriously inaccurate. And even the excellent Taylor salt test kit is only accurate to ±10%. So if you test and get 2800, you might actually have 2500, or 3100! So if those two tests are working against each other, you can easily have way too much or way too little salt for the SWG to operate, even if both the test kit and the IC40 are telling you you're not out of range!! So that's why what these two tests are telling you don't ultimately matter, it only matters that the SWG is making chlorine. And only running the SWG (AFTER THE SALT IS WELL MIXED IN) can determine if the SWG can make chlorine.

That all said, I've yet to have salt build up in my pool, after about three years. My SWG works fine and my salt hovers around 3000. I think its the rain I get, that dilutes my pool enough to keep the salt in check. Your mileage may vary, but until you know for sure, you'll be glad you've added only the amount of salt you actually need.

PS. You don't want patches of extra salty water alternating with patches of near-fresh water blasting through your SWG. The SWG is designed to not operate if there is too much or too little salt, but it only tests for salt content at startup. So in a perfect storm, you start your SWG when the right amount of salt is present in the water, and so it fires up its generator, then the SWG gets a blast of too-fresh or too-salty water and thats'a no good. That's why it's so important to be sure your salt is well mixed in BEFORE you fire up the SWG, and depending on your pool and pump that can take up to 24 hours or more, which is why I play it safe and say wait 2 days (2 days of 24-hour pump run time). Be patient. This takes a while to do it right.

 

[Dirk]

According to poolmath 600 pounds of salt in a 20,000 gallon pool will raise the salinity by about 3585ppm. However, unless this is a new pool that was just filled you don’t want to blindly add salt. Chlorine and some of the other chemicals that we use will also add salt to the pool, so a pool that has been in use for a while will likely have a significant amount of salt already in the water. If you just assume that there is no salt in your water you will likely overshoot your target and need to partially drain and refill the pool to get the salt level back down.

Get a good test kit like the Taylor 1766 (don’t rely on strips) and check the salt level first, then determine how much salt you need to add.

Yep, we were writing our posts at the same time. And salt can come in with the fill water too.

 

[RobertFlagg]

@Dirk @Brett S thank you for all the input. This is a pool that is 30 days old and has been a coloring pool until the 30 day mark. I just put the ic40 inline near the pool equipment and wanted to check before I add that much salt to the pool. I will order the Taylor test kit to supplement my other test kit and plug the numbers in Pool. Math and go the slow route. I’d rather undershoot then over shoot the salt. Thanks

 

[Brett S]

If it’s only 30 days old then there certainly shouldn’t be too much salt in the water. I would feel comfortable adding 3/4 of the salt while you’re waiting for your test kit if you want to get a jump on things. Maybe 1/2 of the salt if you really want to be conservative.

 

[RobertFlagg]

Thanks, Ill probably add 1/2 and let it circulate. The Test kit arrives on Sunday. Leslies has it in stock but it was over $40. Ouch, much better online.

Morton Salt Morton Pure and Natural Water Softener Crystals (40 lb.)-3983 - The Home Depot

This ok for salt being added?

 

[Dirk]

I struggled selecting my salt because they're not generally forthcoming when it comes to listing ingredients. Some softener salts have additives, which you need to avoid, but I don't think that product is subjected to mandatory ingredient disclosure. I even checked on the web but didn't have any luck there, either. Sorry, it's been long enough that I have forgotten what I used. See if you can determine what's in the bad before you dump it in your pool. Or others here will probably know which brand to use. You want to add only pure salt.