Question on Chlorine and CYA Levels with SWG and Pool Temps

[Goob]

I have a question in regards to the [FC/CYA]Chlorine/CYA Chart[/FC/CYA] when using a SWG during colder months when water temperatures are too low.

According to the chart, one should keep the CYA levels a little higher (70-80 range) when using a SWG along with being able to use lower chlorine levels. What levels should I be using when the pool is colder and the SWG isn't producing chlorine? Should I bring the CYA down to the 30-60 range since I am manually adding chlorine.

I'm sure the answer is just keep the numbers in the SWG range, but I haven't seen this addressed and want to make sure.

Have the same question in regards to the CH but wanted to focus on the CYA/FC levels first.

Thanks.

 

[mknauss]

You maintain your FC based on your CYA. But use the non-SWCG chart as you will be adding chlorine in bursts every few days.

With a plaster pool keep your CH above 250 and manage your CSI.

Take care.

 

[Goob]

Ok, been doing pretty good so far and am keeping the FC based on CYA, but I don't know what to do with my CYA when transitioning between seasons.

See the issue? The chart shows higher CYA recommended levels for SWG that are beyond levels recommended for non-SWG. If I can't keep the SWG running due to low temps, do I keep the CYA level up as if I were still using the SWG or drain to bring it back down to the non-SWG recommended levels?

 

[mknauss]

No need to intentionally change your CYA. Just follow the [FC/CYA][/FC/CYA] based on your CYA.

Use the non SWCG chart if using liquid chlorine.

Take care.

 

[Dodger]

Wow, this is a good discussion that I hadn't given much thought to for my first TFP winter. Thanks for raising it Goob.

So at CYA=70, my SWG target FC has been 5, with a minimum FC of 3. Once my SWG stops producing and I need to use liquid chlorine, I have to raise my target FC to 8-10. Is that right? And my previous target (5) will be the minimum!

I just recently let my FC drop from my normal 6-7 down to 4. My SWG is still running, so it should be okay, but I have to reset my thinking so that 4 will no longer be okay during the winter months!

 

[mknauss]

The difference is that using liquid chlorine, your FC peaks when you add, then drifts down, repeat. With a SWCG, you get a more constant dose of FC, so it can be a bit lower.

 

[Goob]

Dodger, that is part of what I was wondering.

While using the SWG, you have a great CYA level of 70 according to the chart. Do you need to readjust the CYA lower to say 50 when the SWG is no longer producing chlorine and you are manually adding chlorine or is it ok to leave CYA at 70 in the winter months although the chart says it isn't recommended to keep it up there?

I understand following the chlorine levels for each CYA level but I don't understand if one needs to bounce between charts (SWG vs non-SWG) based on the time of year and whether the SWG is producing chlorine. I realize I'm making a mountain out of a molehill, so I'm guessing that I just keep the CYA up around 70 for the SWG even when manually adding chlorine. I hate guessing.

Marty, I appreciate your patience with this thick skull!

 

[mknauss]

The fact there is salt in the water does not matter. It is simply how your chlorine is added to the water. If by dosing with liquid chlorine, then you follow the Non SWCG, if by SWCG, that chart. No need to intentionally change the cya level.

 

[Dodger]

While using the SWG, you have a great CYA level of 70 according to the chart. Do you need to readjust the CYA lower to say 50 when the SWG is no longer producing chlorine and you are manually adding chlorine or is it ok to leave CYA at 70 in the winter months although the chart says it isn't recommended to keep it up there?

No, I'm not planning to purposely drop my CYA this winter, though it may drop due to rain water dilution and the drainage I have to do to prevent overflow. (I will address CYA in early Spring to make sure it gets back to the recommended range for SWG operation.) In other words, even though 70 for non-SWG has a "not recommended" asterisk in the CYA/FC chart, Marty is saying we can ignore that for the winter months. We just leave the CYA and use the associated non-SWG chlorine targets when using liquid chlorine.

 

[Goob]

In other words, even though 70 for non-SWG has a "not recommended" asterisk in the CYA/FC chart, Marty is saying we can ignore that for the winter months. We just leave the CYA and use the associated non-SWG chlorine targets when using liquid chlorine.

That's I was wondering but figured to be the case as it seemed that I was the only one not getting it!

Thanks, gents.