How much CYA do I have?

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OldSchoo

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Aug 22, 2010
8
I bought a house with a pool last summer. My first pool, so I had the previous owner give me a tutorial. He used Trichlor pucks in the skimmers and shocked regularly with Dichlor. I took up this same regimen and didn't think too much about it. Frankly it was easy and aside from the occasion algae with a storm- it worked. When I did start testing I found that the pH levels were below 6.8, as read by my initial test kit. I couldn't get the pH to rise so I took a sample to Leslies. They tested it and I was all out of whack. No chlorine, low pH, low CH, high CYA. They sold me some pH up, told me to drain some of the pool water to lower CYA and then bring back another sample. This started a myriad of problems.

So I added the pH up and chlorinated- metal stains. This was about a month ago. Over that time, I've been replacing water- on average I would imagine an inch a day. I lowered the pH back down to 7.2 (from 7.6) and did an ascorbic acid treatment and put in metal free. That worked very well. I decided to shock it last night because the FC had been at 0 for a few days. That turned the water green. No metal stains though. This morning I go back to Leslies and my levels are:

FC:+5 (about 25 based on my 5:1 dilution test)
pH: 7.2
TA: 70
CH: 115
CYA: Still reading 100!

Buy some metal free and 8 pounds of CH Up. Add the CH Up and 16 oz of Metal Free. The CH is now 180 and the pool is getting back to blue (4 hours later). Now my FC levels are back to 0. I added 19 oz of 73% Cal-Hypo to boost the FC and add some additional CH. (I bought the Cal-Hypo right before finding this website- kind of got it by mistake as I intended to replace the Dichlor from the previous owner.)

Where did my Chlorine go? Is in the sun? I would think that the high CYA would make the chlorine more stable to the sun. I read in another post that high CYA's can bind up the chlorine, which got me thinking. How high is/was my CYA and could this be a problem in maintaining chlorine. The previous owner was adding CYA in the tri/dichlor without regard to CYA and the test only goes to 100.

I'm still trading out water and periodically adding MA to keep it at 7.2 to prevent stains. Long story but that's my pool history. And no, I don't have the primo test system yet. Again, I bought the Taylor 2006 kit not realizing that the max FC level it could read was 5.0. Not helpful when your CYA levels is off the charts.

What next? Keep replacing water? Is that my first priority?

Thank in advance. Love the site.
 
OldSchoo said:
Oh yeah... last months water bill was for 19,000 gallons. I've got a spinkler system going twice a week but much of that I'm sure was pool water.
Click to expand...

Time to take charge of your pool and get a FAS-DPD test kit. Don't rely on Leslie's for quality testing...
 
Your first priority is to order and FAS-DPD test to supplement your kit.

Then replace the water to get your CYA down to the 50-70 range. Then adjust PH and add sequesterant. Then begin to chlorinate with Liquid Chlorine or Cal-Hypo. You can use Cal-Hypo until your CH is in the 250 range.

Then do an overnight loss test to confirm if your FC is holding overnight. If its not, you should shock the pool. But sequesterant is key to preventing metal staining from returning.

It can be difficult to get FC to hold after doing an AA treatment.
 
This may be a 'dumb' question, but how much water can I take out before I refill. I obviously need to find a more efficient way to replace the water. The average depth is about 4 feet. Would it be reasonable to take it a foot down before adding new water? I assume I just need to turn the filter off so that the skimmers aren't sucking air. Is that right?
 
One foot then refill is fine. I have drained three feet and refilled before. I don't know how your system is set up but on mine I have a three way valve that can be used to turn off the flow from the skimmers. The only water comming back to the filter is from the main drain, so no chance of sucking air. Then I have a hose bib attached directly to the plumbing just after my filter where I can hook up a hose and put the other end in a ditch behind my house. Open the bib and out goes the water to waste.
 
I was just looking at my plumbing system to see what I would need to do to make a drain past the skimmers (1 foot in total). I have valves in parallel labeled 'drain', 'deep skimmer' and 'shallow skimmer' that are all in the open position. I closed the shallow skimmer just to test and it does indeed stop flow into that skimmer. I also have a underground PVC pipe that is used for 'waste' to the back yard.

Would procedure be to close both skimmer valves and turn the filter on waste. Fill the pool back up and only then turn the skimmer valves back open. That would keep water in the skimmer plumbing when the water goes below them. It seems a no-brainer I just want to be sure I don't mess things up in an expensive way.
 
Flipping the skimmer valves shut seems to work. I'm in the process of taking out a foot of water... Don't know why I thinking of this approach a bit sooner. This should make faster headway on lowering my CYA!

Oh- and the pool is a beautiful blue today. With my recent luck, the fill water will change all that!
 

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A bit of follow-up. I replaced 20% of the water and took a sample back to Leslies to have the CYA checked. Still reads 100- but 'just barely.' Ok- that's as expected because I fear that I have a lot of CYA with the history of trichlor and dichlor in this pool.

I got the TF-1000 test kit today and checked the CYA. I did the test twice and got 40 both times. So now I'm confused. I know Leslie's doesn't have many fans here but we are off somewhere.

Last night I added 16 oz of cal-hyp to raise the FC level to approximately 8.

FC=4 / CC=0. So I lost about 4 in 20 hours.... does that sound like high or low CYA levels?
 
OldSchoo said:
A bit of follow-up. I replaced 20% of the water and took a sample back to Leslies to have the CYA checked. Still reads 100- but 'just barely.' Ok- that's as expected because I fear that I have a lot of CYA with the history of trichlor and dichlor in this pool.

I got the TF-1000 test kit today and checked the CYA. I did the test twice and got 40 both times. So now I'm confused. I know Leslie's doesn't have many fans here but we are off somewhere.

Last night I added 16 oz of cal-hyp to raise the FC level to approximately 8.

FC=4 / CC=0. So I lost about 4 in 20 hours.... does that sound like high or low CYA levels?
Click to expand...
That's low. I'd trust your 40 CYA reading. When you tested twice, does that mean you mixed it up twice and took one reading, or took two readings from the same sample? I also pour the solution back into the bottle, mix it some more, then take another reading, repeating several times until I'm satisfied.

No one will be as interested and careful with your pool water testing as you.
 
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