Does chlorine in powder form raise CYA level?

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NoPool4U

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Aug 23, 2010
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So, I typically always use liquid chlorine. My wife went to the pool store the other day and he told her chlorine powder is more efficient, so she came home with that instead.

Long story short, ever since I started using the powder chlorine, I noticed my CYA level has gone up. Is that the cause? I know the tablets raise CYA levels, so that could make sense...

Thanks!!
 
NoPool4U:

Powdered chlorine comes in several forms, most of which is marketed as "Pool Shock". The most common forms of powdered chlorine are:
  • • Dichlor which will definitely raise the CYA level quickly.
  • • Cal-Hypo (calcium hypochlorite), will not raise CYA but will raise the calcium (CH) level
 
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Thanks! The brand I have is "chlor brite", which is indeed used for pool shock. You'd think the guy at the pool store would know this?! Sounds like liquid is the only option for me since water in CA is already hard as it is.

My CYA level was always around 55. Now it is 88!! Is that way too high or is it still ok? I'm only using liquid chlorine from now on!
 
So, the active ingredient is: "Sodium dichloro-s-triazinetrione dihydrate". So, I assume that is the dichlor you are referring to. Pretty odd that they would market it as "use for shocking or everyday chlorination ?!
 
Dichlor raises the CYA faster than the tablets which are trichlor. Pool stores just do not understand the CYA/FC relationship ... when the cya gets too high and the pool turns green, then they can sell you more "stuff" to try to fix it eventually finally telling you that you need to replace some water to lower the CYA. And then start the process over.

Posted from my Droid with Tapatalk ... sorry if my response is short ;)
 
NoPool4U said:
So, the active ingredient is: "Sodium dichloro-s-triazinetrione dihydrate". So, I assume that is the dichlor you are referring to.
Click to expand...
You got it...that's dichlor. Of the two forms of chlorine that will raise the CYA level (trichlor being the other), dichlor is the worst offender. It will raise the CYA level almost as much as it will the FC level. Continued use of dichlor will cause a "death spiral" in that the CYA will rise to a point that it becomes impractical to maintain a sufficient FC level for day-to-day sanitation. The only solution at that point is a partial drain & refill along with ceasing the use of dichlor.

A CYA of 88 is high. It would be better to get that into the 30 - 50 ppm range. To determine how much to drain, use the Pool Calculator by entering the number of gallons of water in your pool. Then input your current CYA of 88 in the "Now" column and your target CYA in the "Target" column. It will tell you how much water needs to be drained. One thing, though: Do you plan on closing your pool for the winter or leaving it operational? If you leave it operational, I would get it down now. If you plan to close the pool, some of the CYA will be removed when you drain the water below the skimmers. Occasionally, the CYA might go down somewhat during the winter but there is no guarantee. When you get ready to open the pool in the spring, test the CYA level. If it is still higher than 50, drain what is needed and then refill. This will give you a fresh slate to start next year off with.

As you will discover on this forum, much of the advice given at pool stores leaves a lot to be desired. Much better advice that really works can be found in the Pool School articles available on this forum. The off-season is the best time to begin reading these articles so that you will be ready for next year.
 
NoPool4U said:
Sounds like partially draining it will be the only option. I can just use the pool pump to drain the water, right? Same method as backflushing?
Click to expand...


You have to worry about when the water level drops below the skimmer unless you can switch only to a bottom drain. If you can't, others have mentioned putting your vac hose in the skimmer and putting the other end in the bottom of the pool. Of course, this is all assuming there isn't any ground water issues to worry about that might float the shell if the water level is significantly lowered. Also vinyl liner pools can have liner issues as well when draining. What ype of pool do you have?
 
bpricedo said:
NoPool4U said:
Sounds like partially draining it will be the only option. I can just use the pool pump to drain the water, right? Same method as backflushing?
Click to expand...


You have to worry about when the water level drops below the skimmer unless you can switch only to a bottom drain. If you can't, others have mentioned putting your vac hose in the skimmer and putting the other end in the bottom of the pool. Of course, this is all assuming there isn't any ground water issues to worry about that might float the shell if the water level is significantly lowered. Also vinyl liner pools can have liner issues as well when draining. What ype of pool do you have?
Click to expand...

Putting the vacuum hose in the skimmer is exactly what I planned on doing. The pool was replastered about two years ago; it was empty for several days without issues. If I can get my CYA down to about 50, that would be great. I need to use the calculator but I assume I won't need to drain much more than 1/3 of the pool anyway, right?

Now that the temp is down, I don't have any algae issues, so no huge rush I guess?
 

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Wow, brought this up with the pool store and the guy was fighting me tooth and nail that the powder will not increase CYA??! What is wrong with people?? Could it be any more clear?? Guess I'll be going somewhere else for my supplies from now on...
 
bobodaclown said:
If you're not going to be using the pool during the winter. Why drain? Wait till after the winter and check it in the spring. The chlorine demand tends to drop significantly during the winter months.
Click to expand...

I indeed shouldn't be needing much for chlorine this winter but my CYA level won't drop, right? So, I should still do a partial drain before the weather heats up in the spring? On a side note, I'm kinda surprised there is no chemical that can reduce CYA levels.
 
There are quite a few reports of the CYA dropping over the winter ... a bacteria may convert it from CYA to ammonia. If the ammonia is still present in the spring, then you have the combat it with more chlorine, but then you may not have to replace water to reduce the CYA level.

So, you could either change water now or wait until spring to see what condition the water is. Maybe the CYA is lower or gone and you do not need to replace water, or maybe it is still high and you can replace the water then.
 
NoPool4U said:
Wow, brought this up with the pool store and the guy was fighting me tooth and nail that the powder will not increase CYA??! What is wrong with people?? Could it be any more clear?? Guess I'll be going somewhere else for my supplies from now on...
Click to expand...
Show him the ingredients on the Chlor Brite package that say "99% sodium dichloro-s-triazinetrione" or as shown in the More Info in this link on Leslie's website. Also, the Description in that same link says:

• Ultra-Violet Ray Inhibitor
UV rays from the sun can burn off chlorine in your pool. Our granular chlorine has an added UV inhibitor, which slows down this process significantly, keeping your pool sanitized for longer.
:
Dichlor also features a built-in stabilizer, so the sun’s harmful UV rays will not disrupt the chlorination process.
Click to expand...
What does he think that "UV ray inhibitor" or "stabilizer" is? Show him the chemical structure of Dichlor compared to Cyanuric Acid and see if he recognizes the similarities:

Sodium_dichloroisocyanurate_structure.svg
..... compared to .....
320px-Cyanuric_acid.png


Show him this EPA document about Sodium dichloro-s-triazinetrione that says:

The chlorinated isocyanurates are chlorinated derivatives of isocyanuric acid (H3C3N303).
:
The structure of sodium dichloro-s-triazinetrione is given below. The chlorine atoms are attached to the nitrogen atoms, replacing the protons in isocyanuric acid. Thus, the chlorinated derivatives are considered to be derivatives of s-triazine-2,4,6( lH,3H,5H)-trione. Sodium dichloro-s-triazinetrione dihydrate has the same structure except that the material crystallizes with two waters of hydration.
:
Isocyanuric acid is the parent compound for all the chlorinated isocyanurates.
:
To further illustrate and substantiate this characteristic of the release of isocyanuric acid from the chlorinated isocyanurates, additional summaries have been prepared that are included in the Revised Robust Summaries document.
:
Given the extremely short half-life of chlorinated isocyanurates in water, the IIAHC maintains that test data on the more stable isocyanuric acid (CAS No. 108-80-5) or its sodium salt (CAS No. 2624- 17-1) are appropriate for purposes of assessing the environmental and toxicological properties of sodium dichloro-s-triazinetrione and sodium dichloro-s-triazinetrione, dihydrate.
Click to expand...
The problem with the "built-in stabilizer" is that it doesn't go away so builds up over time if you continue to use this product that, according to Leslie's, "can be used for both regular, daily chlorination as well as superchlorination".
 
It's refreshing talking to people that actually know their stuff; thanks for that. I repeatedly told him that there is dichlor in that powder which raises CYA. It didn't matter; he would not listen and kept telling me I was wrong and he's been doing this for 25 years yada yada!! I felt like I was talking to a wall!! I cannot believe people like that work in customer service?!?!
 

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