SWG - Can I Rely on the SWG's Own Salt Readings?

[johnsimion]

I am getting a Pentair IC-40 SWG installed later today. The IC-40 has LED readouts to say whether the salt concentration is low or sufficient, but nothing to say if excessive. First question is whether I can rely on the SWG itself to make that determination or must I buy an actual tester? I live in Vegas where I don't expect to see the salt ever get diluted from heavy rainfall. I figured the best test would be if the IC-40 shows good and the chlorine level is good, the salt level must be good.

Also, the bid included 10 bags of salt to my 19,000 gallon pool "to raise salinity for salt system." Size of bags is unknown. I just went through a drain and refill to get rid of excess calcium and CYA, so I don't want to go over on salt and have to drain and refill again to get rid of excess. Therefore I am planning to tell the installer to only add 5 bags of salt to start with, and that I'd add one bag at a time after that until the IC-40 tells me that the salt is sufficient. Anyone see a problem with that?

Another unknown is that I just drained and replaced 75% of my pool water with soft water. My CH this morning was down to 121. That's too low if it stays there, but it's still adjusting and I don't know how the salt will affect things. If it stays low, I'll actually be adding calcium to get it over 200. Without the excessive calcium in the water, the soft water feeder should be able to keep calcium under control and let the SWG last a long time.

 

[RobbieH]

As long as the SWG is happy, you can be happy.

The bags were probably 40 lbs. Can the installer not test the water before he puts additional salt in?

Salt will not bring your CH up.

 

[chiefwej]

I have salt test strips, but seldom use them. On a new fill, I just calculate how much salt to add. For ongoing levels I depend on the readings on my SWG control panel. It isn't critical and what's really important is that the system is happy and generating.

You must never add salt with the SWG system on. Salt must disolve completely before powering up the system. So adding salt one bag at a time will be a very long process. The bags are no doubt 40 lb each. I have a Aquarite, not IC-40, but my 20k pool fill requires 12-13 bags. You can use the pool calculator to figure out how many bags you need to reach your target ppm. Salt level is not critical, the SWG works well in a pretty wide range.

Your CH is amazingly low! My fill water starts out in the 250-350 range and after a year or two is pushing 1,000, (and that's with my fill line off my water softener). How did you fill the pool with soft water? I know a residential water softener won't begin to keep up with a pool fill. As far as raising your CH, I would wait, and test your water after conversion to salt. Test (I hope you have a T-100 test kit), put your results into the Pool Calculator, and paying close attention to your CSI. See if you can balance your water to maintain the CSI in range without adding CH. You will have plenty of calcium in the pool very soon.

 

[johnsimion]

Actually you CAN fill your pool with soft water, it just takes a long time, dedication to shut the softeners off when they need regeneration, and it took several regenerations. In my case it took about three or four days but the filling started when the pool was only 2/3 or 3/4 empty. It helps that I have both the dedicated outside softener connected to the auto-filler, and my household softener is in the garage where I could run a hose around to the back of the house. It also helped that I have Pebble-Tec that isn't brand new and so I wasn't afraid of leaving it partially unfilled for a couple of days. If it was new plaster, that might have been more of a problem, however right now the water is just beautiful.

I am using the LaMotte 2056 ColorQ Pro 7 and using its numbers and the Pool Calculator, my CSI today is -0.36, which is within the correct range, although barely, and hence you are correct that there is currently no need to add anything (but everything is still adjusting to the new fill anyway). I know I'll have to keep testing and adjusting it daily. Since I am now installing a SWG and all the water that enters the pool will be soft water, however, I don't see where any more calcium would come from unless I put it in.

 

[chiefwej]

I moved my auto fill to my household water softener and I still see a rise in CH levels over time. Although the softener removes a lot of the CH, there must be some left, and since none ever evaporates with the water, the CH level can only go up over time. With our evaporation rates here in the desert, that time is shortened.

BTW: I've been reminded to recommend PoolMath over Pool Calculator.. Less adds and better accuracy.

 

[TreeFiter]

My experience with SWGs has led me not to trust most of them. Some are certainly better than others, but I have seen way too many say the salt is fine, but when tested, it was extremely low. Its not uncommon that I see SWGs that say the salt is at 3000 ppm, but when I test, I find that it is as low as 1500 ppm. I'm not exactly an expert on how SWGs work, but my understanding is that if the salt is below approximately 2500 ppm, the efficiency drops off quite a bit, and the risk of damaging the cell increases significantly. I use salt test strips. Since you are in the desert, you probably won't need to test too often, so a pack of strips will last you quite a while.

 

[jblizzle]

I disagree. The SWG does not measure the salt level, it is measuring the conductivity of the water. As long as the SWG is happy, it will generate FC no problem. I think it is more likely that your test strips are reading low than the SWG is reading high.

The independent salt tests are good to have when the SWG starts to read LOW salt to confirm that the salt level is not in fact low. That is a sign of scaling in the cell or the cell starting to fail.

Also I think the drop-based salt test is much more repeatable and easier to trust than the strips, but that is only my opinion.

 

[svenpup]

With salt just add the amount to get to your target all at once (or at least close to target). The SWCG won't like having only 1/2 the recommended salt.

Using PoolMath and assuming 40lb bags and 19,000 gallons that will bring you to 2500ppm salt. That may actually be on the low side (i think my autopilot manual calls for 3000).

I tend to agree with the general consensus that you ultimately need to make the cell happy, and when the system is new that is fine, but don't forget down the line that a failing or scaled cell will cause a false low salt reading. In that case blindly adding salt because the SWCG is calling for it will cause you to add too much.

 

[TreeFiter]

But isn't the purpose of internal monitoring of salt levels to protect the cell by shutting down when salt levels are way off? If the SWG is happy, it will continue to send voltage to the cell, but if I understand correctly, charging the cell without enough salt will damage the cell. Am I wrong about this?

 

[timerguy]

That's exactly why most will stop generating (sending voltage to the cell) when salt levels are below the minimum or way above the maximum levels required.