Questions about Shocking

hrggat

Member
Aug 26, 2021
8
NW PA
So we changed out the water on our 4 week old tub last weekend using the Chlorine sticky and with advice from you guys. It is crystal clear and staying that way and all of the numbers are dialing in perfectly. Before we were scared to open the cover each morning out of fear of what the water would look or smell like. Now, I love looking in there at my shiny clean water and am a bit obsessed with testing it :).

My question is, in the sticky it says to shock to 12ppm once weekly. If I have been adding dichlor daily as per the directions and never letting it drop below 1ppm, do I need to shock it every week? Or is this the only way to keep the water looking this clear? Also, do I have to add the MPS or is that only if there are going to be a lot of people in the tub or heavier than normal use?

Finally, I never did add borates because I had bought the GentleSpa stuff that is detailed in the sticky but then read posts that it wasn't pH neutral. Our TA has been staying right around 50-60 and pH doesn't seem to budge much above 7.5, so I didn't know whether I should mess with it or just leave well enough alone.
 

Mdragger88

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Jun 1, 2018
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Hernando, Ms
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Chlorine
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You are only to use dichlor until your cya is 30 - you can calculate this by adding up how much u have used & PoolMath effects of adding. About 3oz will add 30ppm cya.
dichlor is acidic so it’s probably keeping your ph down right now but it’s continued use can drop ta too low. Once u switch to bleach u may notice the rise of ph & then wish to add the borates. If u can return the gentle spa you should as regular granular boric acid is simpler & more cost effective to use.
If not you must counter its effects with acid.
Again use poolmath effects of adding to see where it’s addition will land u - it’s tetraborate pentahydrate.
Its not the end of the world if you’re aware of this on the front end.
Many folks here dose to 10ppm or slam level for their cya FC/CYA Chart
when they get out & by they time they use they use the spa again the fc level is reasonable but not zero. You always wanna be above min for your cya so that the tub never goes to zero even while soaking. If its a long soak w/ lots of folks - add some bleach mid session. The recommendation to go to shock level once a week is really more important for those who only replace what is lost during a soak.
A few notes about mps -
*It can read as cc’s on your test without a special interference regeant
*It is only an oxidizer whereas chlorine is both an oxidizer & a sanitizer
*it is not listed in PoolMath
*It can be harsh & we have sensitive skin
For all of the above reasons I have never used it in my spa or pool - I don’t put things in my tub that I can’t test for or get accurate dosing instructions/effects of adding for.
Chlorine alone has always been all the oxidizer I needed. YMMV
 

hrggat

Member
Aug 26, 2021
8
NW PA
You are only to use dichlor until your cya is 30 - you can calculate this by adding up how much u have used & PoolMath effects of adding. About 3oz will add 30ppm cya.
dichlor is acidic so it’s probably keeping your ph down right now but it’s continued use can drop ta too low. Once u switch to bleach u may notice the rise of ph & then wish to add the borates. If u can return the gentle spa you should as regular granular boric acid is simpler & more cost effective to use.
If not you must counter its effects with acid.
Again use poolmath effects of adding to see where it’s addition will land u - it’s tetraborate pentahydrate.
Its not the end of the world if you’re aware of this on the front end.
Many folks here dose to 10ppm or slam level for their cya FC/CYA Chart
when they get out & by they time they use they use the spa again the fc level is reasonable but not zero. You always wanna be above min for your cya so that the tub never goes to zero even while soaking. If its a long soak w/ lots of folks - add some bleach mid session. The recommendation to go to shock level once a week is really more important for those who only replace what is lost during a soak.
A few notes about mps -
*It can read as cc’s on your test without a special interference regeant
*It is only an oxidizer whereas chlorine is both an oxidizer & a sanitizer
*it is not listed in PoolMath
*It can be harsh & we have sensitive skin
For all of the above reasons I have never used it in my spa or pool - I don’t put things in my tub that I can’t test for or get accurate dosing instructions/effects of adding for.
Chlorine alone has always been all the oxidizer I needed. YMMV
Ok, I knew I needed to switch but I hadn't quite added 34ppm yet like the directions said. I just checked the logs and I've added 2.9 oz so by tomorrow I should be there. When I check the CYA test on the TF-100 kit it is just reading 20 right now. Do I go by that test or just assume it is 30 once I've added 3oz?

So basically, if my CYA is 30, PoolMath says my SLAM is 12, so I should just dose up to that nightly? I had been going up to 6 each night and yesterday when it was raining and we didn't use it I tested at nighttime and it was only at 5. I just didn't want to put it up to high and then have it still be high or smelling strongly of chlorine when we went to get in it the next night.

I will hold off on the MPS for now then unless it seems like we need it or have a party.

Thanks for your help!
 

Mdragger88

Bronze Supporter
Jun 1, 2018
2,970
Hernando, Ms
Pool Size
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Chlorine
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Intex Krystal Clear
It really doesn’t matter about the cya that much so long as you are aware of your rough level - it’s just that below 20 is unmeasurable & many people don’t realize they need to calculate the amount. You can start dosing with bleach now or use dichlor a couple more times so long as u are above 20 for comfort’s sake & keep track so it doesn’t get too high & you follow the FC/CYA Chart
The point is just being aware of your levels.
If it’s maintaining fc just roll with it like u are.
No need for the shock level if it will still be pretty high the next time u plan to soak.
The idea is to have enough fc to account for bather waste & that u still have some left by the end of your session. Right now i’m sure you’re testing alot & if it happens to be too low before you get in its an easy fix. u will get a feel for your average use & the tub’s empty consumption.
Again the point is being aware & you are, by testing & knowing where stand so you can adjust as needed - not necessarily being perfect.

Enjoy your tub!
 
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hrggat

Member
Aug 26, 2021
8
NW PA
It really doesn’t matter about the cya that much so long as you are aware of your rough level - it’s just that below 20 is unmeasurable & many people don’t realize they need to calculate the amount. You can start dosing with bleach now or use dichlor a couple more times so long as u are above 20 for comfort’s sake & keep track so it doesn’t get too high & you follow the FC/CYA Chart
The point is just being aware of your levels.
If it’s maintaining fc just roll with it like u are.
No need for the shock level if it will still be pretty high the next time u plan to soak.
The idea is to have enough fc to account for bather waste & that u still have some left by the end of your session. Right now i’m sure you’re testing alot & if it happens to be too low before you get in its an easy fix. u will get a feel for your average use & the tub’s empty consumption.
Again the point is being aware & you are, by testing & knowing where stand so you can adjust as needed - not necessarily being perfect.

Enjoy your tub!
Ok, thank you so much for your help! One last question!
We are going to be away this week for four days. Should I shock it up to the SLAM level before leaving and turn the temperature down a bit? Or is it safe to get the chlorine higher than 12ppm? Now that we have good water I don't want to come back to a problem.
 

Mdragger88

Bronze Supporter
Jun 1, 2018
2,970
Hernando, Ms
Pool Size
26000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Intex Krystal Clear
I would go up to slam level for your cya & turn it down - it doesn’t sound like it consumes but a ppm or so of fc/day when sitting un used at this point.
You may want to be sure the ph is in the low 7’s( 7.2ish) as well so it’s not super high when u return.