Break even point - shock

seanauld

Active member
Aug 4, 2021
25
halifax, nova scotia, Canada
Pool Size
430
Surface
Fiberglass
Chlorine
Liquid Chlorine
Firstly, let me thank all who contribute to this site and the owner/operator. Being a new hot tub owner, I have learned more here in the last month than I thought I needed to learn. The altruism displayed here is nothing short of impressive.I have a quick question as it relates to shocking. The hot tub manufacture , beachcomber (430 gallons, dichlor for the moment) advises to to add 2 1/2 TBs each week of their Carefree Boost - their dichlorvos sanitize each week. This causes the chlorine to jump into the teens, and obviously we can’t use it for approx. 24 hours. When I measure the free Chlorine pre-shock it is usually around 3PPM, with combined chlorine around .5 PPM. If I understand correctly, I need to add 10 Xs the combined CC, which in this case would be enough to bring up to 5 PPM ?

If I added less than the 2 1/2 TBs , but enough to bring up to , in this case 5 PPM, would I have effectively shocked the hot tub.

Many Thanks
Sean
 

Mdragger88

Bronze Supporter
Jun 1, 2018
3,135
Hernando, Ms
Pool Size
26000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Intex Krystal Clear
You should follow the FC/CYA Chart to determine your shock/slam level which may be quite high if your primary source of fc is dichlor. Dichlor adds as much stabilizer as it does fc to the water - the fc gets consumed quite quickly but the cya/stabilizer stays & builds up.
Here’s a handy guide for using chlorine in your spa👇
It is also pinned 📌 to the top of this forum for convenience
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
18,591
Tucson, AZ
Pool Size
16000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
The 10X breakpoint chlorination “rule” is actually wrong. The ASPS and other pool and spa related orgs push that nonsense but it’s incorrect as it’s based on conflicting units of measure. When you take into account the ACTUAL chemistry and use the correct formula units, it works out to about 3X. Even so, if a tub is properly chlorinated and run correctly, you don’t need to worry about breakpoint chlorination unless your are using the tub multiple times per day or you have a huge bather load. Even if CCs build up the the fix is simple - drain the tub and start over.

Don’t forget to follow the Ahhsome purge procedure for your tub. Biofilm build up in the plumbing is the primary cause of FC demand in a tub aside from actual bathers.
 
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seanauld

Active member
Aug 4, 2021
25
halifax, nova scotia, Canada
Pool Size
430
Surface
Fiberglass
Chlorine
Liquid Chlorine
You should follow the FC/CYA Chart to determine your shock/slam level which may be quite high if your primary source of fc is dichlor. Dichlor adds as much stabilizer as it does fc to the water - the fc gets consumed quite quickly but the cya/stabilizer stays & builds up.
Here’s a handy guide for using chlorine in your spa👇
It is also pinned 📌 to the top of this forum for convenience
Thank-you Mdragger88, I had read the post and concerned about the cumulative effects of the CYA, me so was trying to see if I could minimize my addition of Dichlor. Will transition to bleach or bromine soon, though with the kids heading back on Tuesday was trying looking to keep the tub running until after the confusion dies down.

Many thanks
sean
The 10X breakpoint chlorination “rule” is actually wrong. The ASPS and other pool and spa related orgs push that nonsense but it’s incorrect as it’s based on conflicting units of measure. When you take into account the ACTUAL chemistry and use the correct formula units, it works out to about 3X. Even so, if a tub is properly chlorinated and run correctly, you don’t need to worry about breakpoint chlorination unless your are using the tub multiple times per day or you have a huge bather load. Even if CCs build up the the fix is simple - drain the tub and start over.

Don’t forget to follow the Ahhsome purge procedure for your tub. Biofilm build up in the plumbing is the primary cause of FC demand in a tub aside from actual bathers.
 

seanauld

Active member
Aug 4, 2021
25
halifax, nova scotia, Canada
Pool Size
430
Surface
Fiberglass
Chlorine
Liquid Chlorine
Thank-you Mdragger88, I had read the post and concerned about the cumulative effects of the CYA, me so was trying to see if I could minimize my addition of Dichlor. Will transition to bleach or bromine soon, though with the kids heading back on Tuesday was trying looking to keep the tub running until after the confusion dies down.

Many thanks
sean
 

seanauld

Active member
Aug 4, 2021
25
halifax, nova scotia, Canada
Pool Size
430
Surface
Fiberglass
Chlorine
Liquid Chlorine
Thank-you Mdragger88, I had read the post and concerned about the cumulative effects of the CYA, me so was trying to see if I could minimize my addition of Dichlor. Will transition to bleach or bromine soon, though with the kids heading back on Tuesday was trying looking to keep the tub running until after the confusion dies down.

Many thanks
sean
Many thanka joyful noise, I wasnt aware and so very good to know. I will get some cleaner before the drain……
sean
 
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