Mysterious CYA issues

Apr 13, 2018
3
Summerville SC
#1
Hey y'all, I'm just getting on here so forgive me if I've missed a sticky thread on this. I have a 40k outdoor commercial pool which I did a half drain on for cya correction when it opened this year. My initial cya readings were 100++ but I did not run a dilute test at that time since my water was loaded anyways. After the drain and fill (re-chlorinated with erosion fed trichlor to 3 ppm) I was reading 100++ again and ran a few diluted samples with a high level pentair cya kit that gave me anywhere from 120-200 calculated cya. That was 2 weeks ago and I've switched to hand feeding calcium hypochlorate since and swapping 3 inches out a day as well as vacuuming strait to waste but my cya is still around 100ppm. Water is about 68° 7.6 ph and ta is under 60 due to the constant water changes. Do y'all have any insights for me as to what is going on with this pool as I'm at my wits end with the thing haha.
 

woodyp

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Apr 17, 2010
10,206
East Texas
#2
(re-chlorinated with erosion fed trichlor to 3 ppm)
---that's what added the CYA BACK into your pool. Since you've been doing small drains and swapped to calcium hypochlorite----it seems to be decreasing. Just be sure and monitor your calcium levels as well now.
 
May 10, 2017
1,734
Hays, Kansas
#3
Not sure what the 'high level' pentair test kit is but we only trust the Taylor test kit, Taylor 2006c.

A few things could be happening

1 your kit is no good and your cya test is inaccurate. Unless your kit is a rebranded Taylor product I give this one 90%.

2. Your doing the cya test wrong, the instructions for a Taylor is to have the water warmed up, outside on sunny day with sun at your back, pour in to every line and glance at the dot. Pour back into the mixing bottle and test again. There is a 50 ppm standard you can buy to check yourself.

3. Not performing 2:1 3:1 4:1 etc diluted cya tests to finding a actual number.

4. Adding cya in the water with tri clor, di clor, or cya graunles/liquid

5. Cya is stuck in the filter from adding one of the above product to a skimmer or suction side if the pump.

You also should switch to a non-build form of clorine such as sodium hypochlorite, lithium hypochlorite, or clorine gas injection. Triclor and cal hypo have side effects.
 

tim5055

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May 11, 2014
10,087
Franklin, NC
#4
Welcome to TFP!!:handwave:

As has been pointed out, 3" tabs are almost 50% CYA. You need to switch to liquid, SWCG or gas.

Why or why not solid chlorine? In it's natural state, chlorine is a gas. Many large commercial pools actually use gas injection systems to chlorinate their pools. Now, to change chlorine into something we can use at home it needs to be bound to something to turn it into a solid. The "somethings" that are commonly used are stabilizer (also known as CYA), calcium, lithium, or --- get this water. All of these add a little salt to your water, but they add something else. Cal-Hypo adds calcium, Tri-Chlor and Di-Chlor (tabs and most granules) add stabilizer, Lithium hypochlorite adds lithium and liquid chlorine adds - water.

All of these things can be bad for your pool (except the water) in large quantities. The stabilizer helps shield the chlorine from UV degradation, but at higher levels it also impairs the ability of chlorine to do it's work. The higher the stabilizer level you have the higher the amount of chlorine you need. Too much calcium and you start to get scaling on the walls and floors of your pool.
 
Apr 13, 2018
3
Summerville SC
#5
Time unfortunately is why I don't have dilution numbers, very understaffed and the pool is one of many fires to put out but I'll run by tomorrow and do a better work up with exact numbers to post. The cya has been verified (approximately for now) by three separate test kits, one rite out of the box but most accurately by the pentair kit (r15126) which is a bit less subjective than the Taylor kits imho.
As for different non stabilized chlorine what would y'all suggest for a high load commercial pool? I don't have the budget for equipment changes at the moment and it will be getting a salt system when that day comes (please budget gods soon). Forgive my ignorance on the matter, I've always had salt water pools but just took over this property so cya issues and chlorine types are new to me.
 

tim5055

Mod Squad
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May 11, 2014
10,087
Franklin, NC
#6
Well, the big problem you have is that you are running a commercial pool.

At this point it appears you are above DHEC limits as they prohibit CYA above 100. (see page 60 of this document: https://www.scdhec.gov/Agency/docs/water-regs/r61-51.pdf )

You are in a tough spot, because they also prohibit both the hand feeding of chemicals before the pool is open as well as FC above 8ppm.

The only thing I see is a large water change to get the CYA down as well as adding chlorine at night (liquid or CalHypo) but you need to be careful that the FC isn't above 8 prior to pool opening time.
 
May 10, 2017
1,734
Hays, Kansas
#7
I looked up your $20 test kit,I'm just guessing here but it's probably a rebranded hth 4 way test kit. This is not acceptable and it is one of the reasons why your having problems.

I can't speak about commercial pool regulations, but I do know about pool problems.

Moving forward if I was in your shoes first I would order the tf-100 with the xl option or the Taylor 2006c. This is the only kit that gives consistent acur results. The $100 you spend here is a ton more safer then a person to person disease lawsuit because you think your numbers are right.

Then test the cya and drain and refill to get your cya under control.

Then change your clorine feeding to a liquid clorine injection by a lmi pump (or stenner I'd go lmi since i trust their durability). This will cost around $500. Still cheaper than a lawsuit, draining and refilling, replastering since cal hypo sky rocketed your ch etc

Good luck I hope your able to fix it
 
Apr 13, 2018
3
Summerville SC
#8
Alright y'all, sorry for the delay, we had some severe weather this weekend. To address the kit statements, I have 3 test kits, a Taylor 2006 and old high level Taylor kit and the pentair cya kit. They are being used to confirm each reading not provide a single data source.

My cya is now 110 ppm confirmed by 2:1 samples on the Taylor kit and pentair.
So
Cya 110 +/- 10 (need more r13 today)
Ch 210
Ta 70
Ph 7.8
FC 0

That storm did a number on the pool but I'm continuing the drain and fill routine daily. As for DHEC they are legendarily lax here, in fact most cpo's in my area don't monitor cya to my annoyance, and my pool doesn't open till 10 so I can usually get away with hand feeding first thing but would obviously like to get away from it, if a liquid feed system can be implemented for around $500 it sounds like the way to go as I'll spend 3x that in water at this rate. Thanks for the advice, it is much appreciated as I'm in unfamiliar territory till I can go salt again.
 

tim5055

Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
10,087
Franklin, NC
#9
That storm did a number on the pool but I'm continuing the drain and fill routine daily. As for DHEC they are legendarily lax here, in fact most cpo's in my area don't monitor cya to my annoyance, and my pool doesn't open till 10 so I can usually get away with hand feeding first thing but would obviously like to get away from it, if a liquid feed system can be implemented for around $500 it sounds like the way to go as I'll spend 3x that in water at this rate. Thanks for the advice, it is much appreciated as I'm in unfamiliar territory till I can go salt again.
Well, most of us around here who use a liquid feed system use a Stenner Peristaltic pump, but again - we have small residential pools. You would have to calculate the larger pumps and figure their volume along with your pump run time.

I just moved out of Columbia, and a source of the "good" (12%) liquid chlorine was near impossible. I ended up using 8.25% bleach and it worked fine for me, but with your pool you want as much bang for the buck as possible. I would recommend checking out two things before you go too far down the liquid feed road....

First, verify if you have any restrictions on how this system could/would be implemented. I have seen some jurisdictions that had rules like separate buildings or expansive containment systems.

Second, find your source of chlorine. Check with local commercial cleaning services and pressure washing companies as they both tend to buy the 12% in 55 gallon drums. They gotta get it somewhere.