(SWG pool) Adding salt vs. adding chlorine

[ddas]

Trying to cut a long story short here. I'm taking over maintenance of my pool for the first time and am still learning balances, procedures, and chemistry.

I tested my FAC yesterday for the first time in a few weeks, and found it near zero. To double-check myself, I took a sample to Leslie's and they confirmed the same. The guy said to add Chlor-Brite. I said, well, I have a SWG, should I just add salt? He said, if the SWG isn't prompting you to add salt, then no, add chlorine.

My question is: how do I know whether it's better to:

1) add Chlor-Brite
2) turn up the SWG's production (currently set to 20% and running 6 hours a day)
3) add salt (I think I know the answer -- when the SWG tells me to)

I guess my real question is between 1 and 2. I assumed with a SWG I shouldn't have to add chlorine; that I could add salt and let the SWG convert that to chlorine.

 

[zea3]

We need a complete set of test results to get an idea what is going on. Your CYA may be too low and the FC is burning off too quickly.

 

[JasonLion]

In ordinary operation, you adjust the percentage setting. You only add salt or CYA when water test results indicate that you should.

You will only need to add chlorine manually if the pool needs to be shocked.

 

[jblizzle]

Salt is not consumed as it seems you think. You get it in the right range and leave it. Your low FC is either due to the SWG setting too low or something in the water consuming it. You should use bleach to supplement FC if needed to avoid the side effects of granular chlorine.

 

[RobbieH]

If my FC were to get near zero, I'd add enough bleach to bring it up to 3 or 4, even with a SWG. Then adjust the SWG to maintain the proper level.

 

[ddas]

(OP here.) Sorry -- I'm learning my lesson. I'll post the full analysis results FIRST next time:

FAC: 0.5ppm
CC: 0.5ppm
CYA: 90
Alkalinity: 150 (note: after getting this result, I added 1qt muriatic acid)
pH: 8.0 (ditto on the muriatic)
Copper: 0
Iron: 0
Phosphates: 200ppb
Hardness: 200-400

 

[jblizzle]

Well, your CYA is a little high and your FC is too low.

1. Turn off the SWG
2. Raise the FC to shock level (or at least 25ppm)
3. Perform the Overnight Chlorine Loss Test with the pump running all night

If you pass and the water looks clear, let the FC drift down and fire up the SWG
If you fail .... follow the Shocking Your Pool PROCESS

 

[ddas]

Thanks JBizzle. I'll do that.

To clarify: when you say raise the FC to shock level (step 2), you're telling me to add enough bleach to to actually shock it? (Looks like about 4 gallons according to the Pool Calculator -- does that sound right for a 20k gallon pool? Just want to make sure before I add such a huge amount of strong chemical.)

Really appreciate the help.

 

[jblizzle]

You are not "shocking" anything ... what does that even mean? I know the pool stores always say it.

You are elevating the FC level. The poolcalulator puts the "shock" level at 23ppm for a CYA of 90ppm. Pool School says 35ppm. Right now you are just wanting to check the OCLT ... so I would say get the FC up to at least 15ppm or so. That would require 452oz of 8.25% bleach. Which is 3.5 gallons.

You do not need an exact target for this. Just add the bleach, circulate for at least an hour, and test it after dark and then again before the sun comes up.

 

[ddas]

Morning everybody. I used 3 gallons of bleach, ran the Overnight Chlorine Loss Test, and I didn't lose any chlorine. The reading was virtually the same (about 15ppm) late at night, and first thing in the morning. The water is now noticeably clearer. So I guess I'm good!

So I'll turn the SWG back on, and try to find normalcy. Any tips on knowing how high (what %) to set the SWG on? Is it just a game of continually testing for FC and making sure it stays in a good range?

Which brings me to my next question. I just got the Taylor test kit, but they gave me a pretty small amount of the powder to test FC. Just making sure I'm not doing something wrong. Does everyone end up buying a lot more of that powder to be able to test daily or almost daily?

Thanks everybody!

 

[Richard320]

Morning everybody. I used 3 gallons of bleach, ran the Overnight Chlorine Loss Test, and I didn't lose any chlorine. The reading was virtually the same (about 15ppm) late at night, and first thing in the morning. The water is now noticeably clearer. So I guess I'm good! No, keep the FC elevated until the water is totally clear. The algae may just be hiding out regrouping for a counterattack.

So I'll turn the SWG back on, and try to find normalcy. Any tips on knowing how high (what %) to set the SWG on? Is it just a game of continually testing for FC and making sure it stays in a good range? Yep. Also note if you set the pump to run longer, you might need to reduce the SWG %

Which brings me to my next question. I just got the Taylor test kit, but they gave me a pretty small amount of the powder to test FC. Just making sure I'm not doing something wrong. Does everyone end up buying a lot more of that powder to be able to test daily or almost daily?

Thanks everybody!

Yes. That's why I ordered the XL option right at the beginning. When you order refills, go ahead and get a speedstir, too. You won't regret it. You probably ought to go ahead and get some more CYA reagent, too, since the K-2006 is pretty skimpy with that.