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Hi , i use the trichlor tabs and i want to free up some of the CC but preferably without adding any extra CYA to the water. The only thing ive found thats compatible with trichlor is the ‘pro side shock’. I know i cant use the standard type of shock but is there something else that’s compatible without the added CYA in it like the pro side or is that the only one i can use? P.S i accidentally write this on someone else’s comment by accident. My apologies. 

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Ummmm... Either you have mixed up some abbreviations or you don't understand pool water chemistry. 

FC= free chlorine. The stuff you want that sanitizes the water

CC= combined chlorine. The result of FC combining with organic contaminants in the water, aka sanitizing. The stinky, eye burning stuff you DON'T want, and that you shock to get rid of.

TC= total chlorine. FC + CC = TC

Your test can only measure FC and TC, so you have to subtract FC from TC to find CC. TC - FC = CC

Shock is ANY oxidizer that burns off CC. Chlorine is an oxidizer, as is MPS (monopersulfate, non-chlorine shock), ozone, and even hydrogen peroxide.

CYA= cyanuric acid, aka stabilizer. This is like sunscreen for chlorine, and you want it around 30ppm. The higher above 30ppm it goes, the more it interferes with the chlorine combining with contaminants (overstabilization), so the higher the FC level must be to sanitize the water.

Some chlorine (dichlor, trichlor) is stabilized, meaning it contains CYA. So while the FC turns to CC and is then destroyed by shock, the CYA just builds up, until you have overstabilized. The only way to lower CYA is to dump water and refill.

I do not recommend the use of trichlor tablets. Not only do they contribute to overstabilization, but they are acidic and will lower ph continually which can damage equipment, plaster, and vinyl. Use liquid chlorine (sodium hypochlorite, aka bleach) any add CYA manually to establish 30ppm residual.

@waterbear, did I sum it up fairly well?

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9 hours ago, Nichole said:

Yes I understand the chemistry and no you didn’t answer my question. Thanks though 

1) no need to be rude

2)no you don't understand the chemistry or you would have worded your question differently

3) I believe that you are asking what oxidizers (shocks) you can use with trichlor that will not add more CYA to the water. The answer is that you can use any form of  unstabilized chlorine or you can use MPS., Unstabilized chlorine sources are sodium hypochlorite (liquid pool chlorine or chlorine laundry bleach), Calcium hypochlorite (cal hypo), or Lithium hypochlorite (lithium shock). You do not want to use dichlor (Dichloro-S- Triazinetrione) since it adds CYA faster than trichlor does. Trichor adds 6 ppm CYA for every 10 ppm free chlorine added, dichlor adds 9 ppm CYA for every 10 ppm free chlorine added. Also, take note that cal hypo adds 7 ppm Calcium for every 10 ppm added which can also be a problem.

4) if you understood the chemistry then you would have realized that @RDspaguyDID answer your question and, in fact, if you understood the chemistry you would not have asked the question in the first place.

I hope you find this useful.

I deleted your post in the other (11 year old) thread so all your answers will be in one place.

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I was being rude but i also know you cant mix sodium or calcium hydo with trichlor because it causes a reaction (from what i read) its a small pool and im trying to avoid that. Many many articles expressed that you can not mix those 2 with trichlor so whats the reaction with the lithium and trichlor? My question was the ‘pool side super shock’ product with trichlor, is that the only one thats 100% compatible without a bad reaction? 

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3 hours ago, Nichole said:

I was being rude but i also know you cant mix sodium or calcium hydo with trichlor because it causes a reaction (from what i read)

You misunderstood what you read. The caution was about mixing the actual chemicals. . Once trichlor is dissolved in the pool it becomes hypochlorous acid, cyanuric acid, and chlorinated isocynurates. If you add liquicd chlorine to a pool that had CYA in it you get exactly the same thing. If you are using trichlor in a feeder you can put the feeder on bypass before shocking or adding acid (another no mix combination!). If you are using a floater just take it out. ALL forms of chlorine, once dissolved become hypochlorous acid along with some other basically inert metal ions (sodium, lithium and/or calcium). If you are using a stabilized chlorine or have added cyanuric acid to stabilize a non stabilizied chlorine you will also have cyanuric acid and chlorinated isocyanurates present.

In actual practice, you can add any form of chlorine to shock a pool that is running trichlor without bypassing or taking out the trichlor. Just don't pour the shock next to the skimmer, drain or floater and make sure the pump is running. It's always a good idea to predissolve a powder shock in a bucket of water and 'walk" it around the pool as you pour it in.

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3 hours ago, Nichole said:

Never mind. Pool guy on a different forum answered my question with one sentence. 

Would love to see what he said if you wouldn't mind posting it here.

Also, If you feel you don't need this forum then let me know and I can remove you from the membership.

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