adjusting the SWCG - what's "normal"

[davelinde]

...so we are away for the summer and got a house sitter to care for our pool. My hope had been that by this point the chlorine would be running like clockwork and no worries. Instead I now get to hear what my wife says the house sitter sees... anyway -- just before we left it seemed the pool was not holding chlorine so I inspected the SWCG (it has never been cleaned since new) and all the plates looked shiny and fine (I assume that buildup is like a chalky white?) My wife said that salt was "fine" (and the idiot light was green too) so I figured OK. So we did one last shock before leaving. We passed an OCLT but then the skies opened and it rained like crazy. The last thing we did was pump 2" of water to get the pool below even with the coping.

The house sitter is also reporting we aren't holding chlorine so we had her shock and do an OCLT too. No over night loss and finally now... the low salt light came on. So today she added salt and now we will see.

I think the situation is clear? As the salt level approached the minimum but still "OK" the rate of chlorine generation dropped and we were not keeping up with the daily loss. The rain diluted the water more and the salt level went below minimum, so hopefully we just need to bring it up and all will be good again? I suppose there is no "right" answer but between the time since startup (3+ months) and the rain we just got to the point we needed salt - how often should we "expect" to be adding salt? It seems it might be better to keep it above some level vs letting the idiot light tell us we are not making chlorine now?

 

[ping]

Every pool will be different on how often salt will need to be added. The first winter we had a lot of rain in a two week time frame and I had to drain the pool some 6 to 9 inches of water and I had to add a couple bags of salt. Since then, two years, I only had to add one more bag of salt.

Since you don't backwash, your replacement amount will depend heavily on how much water gets drained and splashed out. If you raise it towards the higher end of the suggested amount you will not have to replace the salt as often. Having test strips or having a pool store test the salt level is recommended before blindly adding salt to the water. I bought the K-1766 salt test at TFTestkits.net, but I was having sensor problems with my SWG and I just wanted to eliminate things the best I could on my own.

 

[davelinde]

Every pool will be different
...raise it towards the higher end
...Having test strips or having a pool store test

I figured there could be a range of experience here. I'm also wondering how accurate the salt tests are...
We have strips and took it to the pool store and pretty much got the same reading (mid range) with no variations for months, including just days before the low salt light went on. My wife told me she had the house sitter add a full bag of salt, which should bring our smallish pool up near the top of the range.

We go from here... and we will see.

 

[davelinde]

We go from here... and we will see.

Well... it appears we have been able to coach our house sitter through this all by phone and the pool has been dandy for a while now! The last tuning was to raise the salt level a bit and now the FC levels are holding. The house sitter says that heavy rains disrupt it some so she is just dumping some extra chlorine in after a lot of rain and it's been fine.

Can't wait to get back home and swim in it! I feel like I spent all winter building it... all spring getting it running right and we are gone for the summer and missing the fun part

 

[davelinde]

So a quick update here and a "THANK YOU" to this forum. When we got back and took over from the house sitter our FC levels were not so stable, although the pool was clean and clear. We were out of the tests too, so the first stop was the pool store who told us that both salt and CYA were low. After we added more CYA (a lot more actually) the FC started rising and we gradually turned down the duty cycle on the SWG to the lowest setting. All has been good ever since.

I guess we were a bit to cautious about getting CYA too high and didn't think it could drop so much that we were not checking that as we should. I'm still not sure how it dropped so much, but I guess it did, and now that it's higher again, all is well.

 

[linen]

We were out of the tests too, so the first stop was the pool store who told us that both salt and CYA were low. After we added more CYA (a lot more actually)

Hopefully they are right, but I wouldn't bet on it, pool stores are notorious at getting this one wrong. Next time, wait for you test kit to adjust. Cya typically does not drop much (it is not a consumable) unless you exchange a lot of water. Post your cya result when you get your refills.

 

[davelinde]

We were out of the tests too, so the first stop was the pool store who told us that both salt and CYA were low. After we added more CYA (a lot more actually)

Hopefully they are right, but I wouldn't bet on it, pool stores are notorious at getting this one wrong. Next time, wait for you test kit to adjust. Cya typically does not drop much (it is not a consumable) unless you exchange a lot of water. Post your cya result when you get your refills.

Well... I might have been suspicious of their results except adding that CYA changed us from needing a fairly high duty cycle to hold chlorine levels to a low duty cycle holding the level with no problem. So the result seems to validate the measurement?

I am a bit unclear about where the CYA went... except the house sitter did mention there was a lot of rain and that they never added water but did pump some out.

 

[jblizzle]

Re: adjusting the SWCG - what's "normal"

All that proves is that your CYA is now higher which you know because you added it. Does not prove it is not now higher than we would recommend.

 

[bmoreswim]

I couldn't help but to think when reading your posts that you are managing your pool by a bit of a committee. I would take over the testing myself and eliminate the miscommunication there seems to be on that front. Getting that annoyed look regarding water chemistry only clouds the issue . For me managing my pool (which is a new SW pool) feels like both art and science. The art of it is that due to various factors affecting the pool I try to make an educated guess regarding what my pool needs, then I test to verify and proceed. It's been fun to see how often I am correct. But the tests are always my foolproof backup before adding chemicals.