Brand new pool owner questioning CYA reading

Jump to latest Follow Reply
A

AWeiler

0
May 22, 2017
7
Mesa, AZ
Hello:

I just tested CYA and my test kit is a Taylor Tech K-2006 testing kit. I pulled a sample of water and then added the prescribed regent and mixed it. Then the directions are to pour the mixture into the tester drop by drop until the black dot on the bottom of the tester disappears. The dot disappears before the water level registers on the scale. So I interpret this as way above 100 (ppm?). I retested and it is the same.

Can i trust this measurement even though it is way high off the chart?

My ph is 7.6, FC was really low at just under 1ppm and CC didn't register at all.

I have very small amounts of green algae that i chased away with a bag of shock and i can brush the spots off easily. My water is very clear and it seems balanced (low odor and not irritating eyes).

So i want to add chlorine. But i can't calculate the amount of chlorine to add until i have an accurate CYA level yes? And, do i add chlorine if i am going to backwash and do a partial drain to lower CYA.

I know i have a lot to learn and have been spending 30 minutes to an hour reading this site each day since it was recommended to me.

Thanks in advance for any advice you may give.
 
Yes, you can trust this measurement, especially if you have used trichlor pucks or dichlor granules to chlorinate your pool. Dilute your pool water sample 1 part pool water to 1 part tap water and stir it up. Use this solution to test the CYA. Double the result to get a ballpark idea what your CYA level is currently. From there you can determine how much water you will need to replace.
 
Welcome to TFP! You're doing great, asking great questions, have a great test kit, and reading pool school! you're on the way to being a TFP master! Take a moment to give yourself the praise you deserve, and don't let this overwhelm you. One thing at a time. Keep asking questions! You got this.

Just to confirm a couple things first:

1. you did your CYA test like this video shows: Testing Cyanuric Acid with the TF-100 - YouTube (yes your bottle and dot are a little different, ignore those details)
2. on a bright day, outside, the dot goes away before the water goes up the tube and gets to 100, correct?
3. If so, follow step 8 on this page to get your real CYA of 100+: https://www.troublefreepool.com/content/220-CYA
4. until someone with expert, mod squad, guide or something higher than me tells you, get FC in the 11-13 range and keep it there. This is only slightly above shock if your CYA is actually 20 and is the target range if your CYA really is 100+ so it is a safe, in my opinion, goal for you until experts chime in.
 
Thank you for the advice. I have been using pucks and i am switching to liquid. I treated with about 90 oz of 10% bleach (pool chlorine from Wal-mart). I thought pool bleach was supposed to be 12%?). I will check values again in the AM. I am running my pool pump over night.
 
Thank you for the tips and especially the video. It appears that i was doing the test correctly.

I will retest CYA in the AM using the dilution method along with the other tests. I saw an example of the test values that I should be performing and the format to report so I will follow that tomorrow as well.

I went ahead and added about 90oz of liquid chlorine by pouring it slowly in front of a working jet and into the waterfall from my spa. Then i swept the pool thoroughly. I will let the pump run overnight. Based on what i am reading, i don't think i will be near the 11-13 ppm range recommended. But as a newby, it felt odd adding a whole 120 oz at one time. Plus, if I am going to be exchanging a lot of water out of my pool, i don't want to add a lot of chlorine. Also, we are hoping to be swimming over the holiday weekend.

I love that there is a method to predict how much water i will have to exchange out of my pool.

Thanks again for your detailed reply. I really appreciate it.
 
Sounds good. Look forward to getting the dilution results and your CYA. Then, either drain/fill or getting your FC to shock value per the CYA chart and keeping it there. Pool bleach is oftentimes either 10 or 12% and even though it says 10% it could be anywhere from 0% to 12.5% depending on freshness. Same exact chemical as regular bleach only stronger % strength. Still blown away that I didn't know that for years :) You're doing great.
 
I retested this AM (5/27/2017)
FC: 4.0 ppm
CC 0.4 ppm
pH 7.6
CYA 400+ ppm
H2O temp: 78 degrees

I diluted the CYA test by 100% using tap water and the reading was still off the chart high. I diluted it by 200% (1/4) and it measured just below the 100 on the scale (which isn't linear). So really don't know what my CYA is other than REALLY high. Based on the video kindly linked by BattleOfYakima and this document: http://www.taylortechnologies.com/ChemistryTopicsCM.ASP?ContentID=44 I'm doing the test correctly.

I'm guessing that i should add more chlorine. Yes? Pool math says another 49 oz should move the pool up to 6 ppm. I have removed the Chlorine tab dispenser. I'm not near the 11 - 13 ppm for FC that was recommended on this post.

It's seems a little crazy because the water is clear, with little to no odor (I can barely tell i more than doubled the chlorine concentration). I haven't backwashed the pool in some time. Should i move on to the calculation of how much water to take out or do something else?
 
Last edited:
With CYA that high you are going to use a ton of liquid chlorine just to keep algae at bay, and it could turn on you very quickly. I would drain and replace water to get the CYA down to a manageable level. If you want you can wait til after the holiday to change the water, but I wouldn't wait a whole lot longer than that.
 
Thank you Zea3 and JStephens1.

I backwashed my pool and tried to reduce the water volume. I added more liquid chlorine. My FC is now 6.4 ppm. I also added as much water back as i can. I will recheck my FC to make sure it peaked. I will keep testing and keep it chlorinated over the weekend and then replace more water. Someone, maybe BattleofYakima indicated that there is some pool math which would estimate how much water i would have to exchange to bring my CYA down to acceptable levels. Can anyone point me to that tool?
 

Enjoying this content?

Support TFP with a donation.

Give Support
With a CYA of 400+ you essentially need to replace all your water. Doing it via backwash will take a huge amount of water. I suggest renting a submersible pump from Home Depot or buying one from Harbor Freight. As you are in the desert you will need to keep your plaster wet during the drain and refill or it may crack.

You typically will be changing the water in the pool every two years no matter how you chlorinate due to your high CH fill water. So best to plan to do it in the winter when we have less concern of drying plaster and cracking.

Good Luck!
 
AWeiler said:
Thank you Zea3 and JStephens1.

I backwashed my pool and tried to reduce the water volume. I added more liquid chlorine. My FC is now 6.4 ppm. I also added as much water back as i can. I will recheck my FC to make sure it peaked. I will keep testing and keep it chlorinated over the weekend and then replace more water. Someone, maybe BattleofYakima indicated that there is some pool math which would estimate how much water i would have to exchange to bring my CYA down to acceptable levels. Can anyone point me to that tool?
Click to expand...

Up at the top of each page is an oval that says PoolMath. That is the tool that allows you to determine how much you need to drain and what chemicals to add. We recommend using a series of drain and refill cycles to get the CYA down to where it should be.
 
Philo said:
I'm not a moderator..... but, I think when you get to 400+ on CYA there is something called "chlorine lock" in which no matter how much chlorine you add (within reason) it will become ineffective and green water is right around the corner.
Click to expand...


Welcome to the thread Philo! Without getting into details, maintaining a pool with CYA greater than 80 is hard, over 100 is harder, over 200 starts to have luck or wasteful excess bleach expenses, over 400 is almost always safer and cheaper to replace at least half or more of the water. CYA test has a +/- margin of error, which only gets bigger and bigger as you start diluting. Pages of info and dozens of links in this thread. But the pool store "chlorine lock" is a best misleading and at the extreme a flat out lie. I'm not an expert on that, but that thread also addresses it.

For the purposes of AWeiler's pool - I'm hoping that a roughly 80% at once drain/fill if safe/manageable or, if needed, the generally safer multiple partial rounds of pump out/fill/repeat that just uses more water and time, but otherwise yields the same end result: CYA 80. Hopefully AWiler isn't stuck with this water.

If....for some unholy reason, you're stuck with this water and want to attempt to keep it sanitary - this thread has math for CYA above 120, but again, you should know you're out of science and into guesswork since your testing isn't meant for these ranges.

I was curious, so I ran some math, using that thread's math..
CYA 420 MIN FC 31.5 Target FC 46 Shock FC 168
and in order to bring the 19,000 gallon pool to shock from zero fc would be 39 jugs of 121oz 8.25% bleach
 
You must log in or register to reply here.
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Top Bottom
Back
Jump to latest Follow Reply