Does Sodium hypochlorite (12.5) raise cya?

Bobswe

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LifeTime Supporter
Jun 12, 2012
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Cinnaminson NJ
I've been using sodium hypochlorite in lieu of Dichlor to try and get a fc reading. I do use trichlor during day to supplement it but my cya seems to be rising too fast. I was under impression liquid chlorine didn't raise cya. I know trichlor does but it's not enough to raise this fast. Cya 80, fc 0, tc1, ph 6.8, ta 70. Cya was 40 about a month ago. What's the deal?
 
Bobswe said:
How much liquid chlorine would one normally add in the morning rather than trichlor pucks in a 21,000 gallon pool? I've been putting 2.5 gallons in weekly and pucks in during the day. I do not use any dichlor.
Have you used the PoolCalculator.com yet? It will figure you doses for you.

But, with a CYA of 80, your FC should be between about 6 and 11, and never below 6.

[s:49usisa7]What % liquid chlorine are you asking about?[/s:49usisa7]
Assuming 12.5% liquid chlorine, to raise FC from zero to 11, you would need to add about 230 ozs (or, 1 gal, 3 qts, + 3 cups).
 
Starting to use liquid chlorine solely. When would be best time to add to pool if I usually run filter 10 hrs a day usually during the daytime hours, However, it is often that I'll run filter 2 hrs extra during the evening for circulation.
 
The pool calculator says shock level for a pool showing a cya needs to be held at a fc reading of 21. Having algae with clear water should take about how long to rid it of the cc reading? Im just looking for aprox. 1 day, 2 days? I know to continue until it starts to hold on itself but was looking for aprox.
 

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Bobswe said:
The pool calculator says shock level for a pool showing a cya needs to be held at a fc reading of 21. Having algae with clear water should take about how long to rid it of the cc reading? Im just looking for aprox. 1 day, 2 days? I know to continue until it starts to hold on itself but was looking for aprox.
No way to predict - too may variables. How green is the pool? How much organic debris? How good is the circulation? How religious are you about replenishing lost FC? How religious are you about brushing? How thorough are you about getting back behind the light?

Bare minimum, 3 days. One poor guy here a while back took almost a month to finally pass the overnight test.
 
Wow. Can algae really hold on that long? My Water has stayed clear. I do see some algae forming along seem that i brush off. I inderstand what youre saying about the work that's involved. I never seem to get full blown algae maybe because I have some metal readings that I try to contain with pro team metal magic. I work long hours but am home from dusk til dawn. I've used liquid chlorine to try and shock several times this year but not sustained over days. In doing it once a week I have not "really schocked" the way it needs to be but always wait for liner to restain. Having a cya that's slowly rose to 80-90 finally made me stop with trichlor as of yesterday. Does the liquid chlorine have to work harder due to the metal sequestriant also?
 
Bobswe said:
Does the liquid chlorine have to work harder due to the metal sequestriant also?
Chlorine will break down the metal sequestrant. If it's EDTA-based, it will result in a noticeably higher chlorine demand. If it's HEDP-based, as recommended on this forum, then you probably won't notice the difference in chlorine demand.
 
ProTeam® Metal Magic is HEDP so is probably not contributing very much to chlorine demand. As for when to add it, I would add it when the chlorine level is normal and not at shock levels (so not the same time you are shocking). Though HEDP is chlorine resistant, it does slowly break down from chlorine so there's not much sense in using it at the same time. If you want to make sure metals are being held well when you are shocking, then yes add the metal sequestrant a day or two before you shock, but if you find that shocking doesn't lead to new staining, then adding your maintenance dose after shocking has returned to normal FC levels would be better (in terms of not breaking down HEDP as quickly).
 
I'm 2 days into my shocking with liquid chlorine. They sell it at bj's so I bought several cases. I've been shocking at or a little above 21ppm consistantly. Today I vaccuumed to waste any algae fallout and it has not reaccumulated yet. I hope to pass overnight test soon as I go away saturday. I've noticed that u cannot check for cc when chlorine is so high, is that the reason u need to pass the overnight chlorine test to know you're algae free. The other question I have is I need to use a solar cover when I go away as I'm surrounded by trees. I want to avoid any trichlor so can liquid chlorine go in under the cover near a jet. I'll be gone 7 days and my daughter may take cover off here and there but it will mainly stay on. I swore off trichlor so prefer to continue with the liquid chlorine (12.5). Any suggestions?
 
Bobswe said:
...I've noticed that u cannot check for cc when chlorine is so high, is that the reason u need to pass the overnight chlorine test to know you're algae free...
You can check for CC at any chlorine level. It's part of the OCLT test and is routinely tested at shock levels. It's the PH test that reads falsely high when Chlorine levels are at 10 ppm and above.
 

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