Weekly shock?

mzman88

New member
Apr 16, 2020
3
Ooltewah, TN
I’m a new hot tub owner. A friend with a pool directed me here to learn about the chemistry needed. I’ve followed the sticky for chlorine at the top of this section.

I’m currently on day 8, on initial fill I used 10ppm chlorine then every day I’ve been testing and before and after every use. I just reached 34ppm dichlor and am about to switch to straight pool bleach.

What I’m trying to figure out right now is in the sticky it recommends shocking to 12ppm once a week. Would I be shocking with dichlor/bleach or non chlorine shock? If it’s chlorine how do you work that in to the schedule so you can use the spa 7 days a week. If I were to shock to 12 I’d probably have to wait 2 days for it to come back down to 6ppm FC.

Is this something I need to be doing if I’m checking and adding chlorine every day?

Thanks for the advice!
 

mzman88

New member
Apr 16, 2020
3
Ooltewah, TN
No, I haven't added any extra. Only what the dicholr adds. If I'm reading the guide right after I reach 34ppm total dichlor added I should be at roughly 30ppm CYA?
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
16,481
Northern NJ
No, I haven't added any extra. Only what the dicholr adds. If I'm reading the guide right after I reach 34ppm total dichlor added I should be at roughly 30ppm CYA?

Yes, Dichlor about 1:1 in chlorine vs CYA.

If you know your CYA level you can determine the safe FC level. With CYA 30 your safe to use the water up to SLAM FC of 12. See FC/CYA Chart
 

jseyfert3

Bronze Supporter
Oct 20, 2017
682
South-Central WI
Thanks, Do I need to be raising the FC to 12 on any kind of schedule?
While I'm not always the best at adding chlorine regularly (which is part of the reason why I've just purchased a Saltron Mini SWCG for my spa), my goal is to add enough chlorine when we get out of the spa so that it doesn't drop below the minimum FC level for my CYA by the next day when I check it, at which point I boost it back up to the top of the target range on PoolMath. My wife and I often soak for an hour or two. The FC is usually 4-6 when we get in (30-40 ppm CYA), and while I don't test it when we get out it's likely low or close to zero. I've been adding about 4 oz of 12.5% bleach recently which adds 8.7 ppm FC, and that seems to do the trick. If the FC was lower when we got in, we stayed in especially long, or had friends in with us I'll add even more when we get out. Additionally I'll boost it to the SLAM level (12 ppm for 30 ppm CYA) if we're getting in their with friends for a long soak, before we get in.

That said, it certainly doesn't hurt to regularly take it up to 12 ppm. Keep an eye on your CC levels, they will also tell you if you need to shock. If you're seeing over 1 ppm CC that's not good.

Would I be shocking with dichlor/bleach or non chlorine shock?
Liquid chlorine, generally. Not dichlor after you're reached 30 ppm, unless your testing shows you need more (heat and FC decays CYA, so you should test once in a while that you still have what you think you have). You can use non chlorine (MPS), but keep in mind MPS show up as CCs in the FAS-DPD test unless you get the reagent from Taylor that removes the influence of MPS from the test.
 

wpgswim

Member
Apr 3, 2017
5
Winnipeg, MB
Liquid chlorine, generally. Not dichlor after you're reached 30 ppm, unless your testing shows you need more (heat and FC decays CYA, so you should test once in a while that you still have what you think you have). You can use non chlorine (MPS), but keep in mind MPS show up as CCs in the FAS-DPD test unless you get the reagent from Taylor that removes the influence of MPS from the test.

How long does the influence of MPS last?
 

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