Cyanuric Acid

[Bcorig]

Tested and adjusted CYA in June and got it up to 80 using granular CYA. Took two days to dissolve it.
Just checked and found CYA =35 after only 2 mos which surprised me.
It has been hot and sunny in SoCal but we did have two days of rain a week ago.
Current Chemistries CYA 35 TCl 7 (80% SWG 8 hour/D Variable speed pump). PH 8.0 TA 60 Salt Green on ic40
I’m thinking of liquid CYA replacement since the granular is so difficult to dissolve.
1. Is anyone surprised at the the drop in CYA after only 2 mos?
2. Liquid vs Granular?
Tx

 

[mknauss]

That drop is pretty extreme. You can see maybe 10 ppm per month drop in your area in summer. Did the rain overflow the pool?

I use granular CYA. Put it in a thin sock and drop it in the skimmer. Leave the pump running and it will dissolve in a few hours.

 

[Bcorig]

That drop is pretty extreme. You can see maybe 10 ppm per month drop in your area in summer. Did the rain overflow the pool?

I use granular CYA. Put it in a thin sock and drop it in the skimmer. Leave the pump running and it will dissolve in a few hours.

1. The pool water did overflow into the drain (I was out there watching it)
2. Is there any downside to liquid?
Thanks for the reply.

 

[mknauss]

Only downside to liquid is you really should use the entire bottle. It clumps up and is very difficult to get mixed prior to using some of it. Also cost. 3-4X the price of granular. Cost of the granular has come down some. Amazon is showing 4# for $13.

 

[Bcorig]

Only downside to liquid is you really should use the entire bottle. It clumps up and is very difficult to get mixed prior to using some of it. Also cost. 3-4X the price of granular. Cost of the granular has come down some. Amazon is showing 4# for $13.

Thanks for your responses.
15500 gal pool. SWG
The PoolMath calculation = 72 oz by weight of granular CYA to raise CYA to 70 from 40.
I added 28 oz (40%) by the sock method yesterday.
This morning CYA = 70
I’ll check again tomorrow.
This has been my experience with CYA - all estimates are approx 50% over what is needed.
Side note: The sock required constant manipulation with a rubber-gloved hand to disperse the CYA. It took about 30 minutes to empty 28 oz. Filter pressure never changed from 14 PSI.
PS:
When I started balancing with TFP the pool tiles were stained with CaCO3 - now that scaling is almost gone.
Thanks!!! This site is amazing.

 

[BDY]

Re the sock - leave it soaking for a few hours then squeeze it - it will make it much easier. Anything left let soak another hour or so.

I don’t use a glove as my hand is in the pool water the whole time but it’s a personal preference —- I would say that water will get in the glove usually

Re the readings - anytime with a sharp change in readings like CH or CYa (the long term chemicals) I would make sure the pool is mixing well for at least 30 min and then retest…. Be suspicious of weird readings that aren’t logical for your pool “norm” until confirmed a number of times

 

[Mdragger88]

How certain are you of your pool volume?
You can use these to help better calculate your pool volume

PoolMath

Discover the calculator behind the perfect pool, PoolMath. Dealing with pools has allowed TFP to become the original authors of the best calculator on the net.

www.troublefreepool.com

Pool Volume Calculator

Check out Pentair's easy-to-use pool volume calculator to calculate the volume of your swimming pool water by choosing the shape, dimensions and depth.

www.pentair.com

Also fine tuning it with acid dose results &
PoolMath
Being a little off is one thing but that’s way off.

 

[kul]

Hi, I had a similar observation, but less than yours. I had a CYA of 60 and it went down to 40 after a couple of months of summer. I’m not sure why, but think it was related to pouring in excessive chlorine because I was going to be out of town and doing a slam (because I thought pollen was mustard algae). I did have to drain some after the recent storm, but it was not a huge amount so I’m not expecting a big shift in CYA.

 

[Bcorig]

How certain are you of your pool volume?
You can use these to help better calculate your pool volume

PoolMath

Discover the calculator behind the perfect pool, PoolMath. Dealing with pools has allowed TFP to become the original authors of the best calculator on the net.

www.troublefreepool.com

Pool Volume Calculator

Check out Pentair's easy-to-use pool volume calculator to calculate the volume of your swimming pool water by choosing the shape, dimensions and depth.

www.pentair.com

Also fine tuning it with acid dose results &
PoolMath
Being a little off is one thing but that’s way off.

Thanks. Its an irregular curved shape pool with an attached rectangular spa.
2 years ago I re- calculated the volume of each rectangular section using average depths in each rectangle - I still have my notes - I can redo it. It was the method described in Pool Math.

Re the sock - leave it soaking for a few hours then squeeze it - it will make it much easier. Anything left let soak another hour or so.

I don’t use a glove as my hand is in the pool water the whole time but it’s a personal preference —- I would say that water will get in the glove usually

Re the readings - anytime with a sharp change in readings like CH or CYa (the long term chemicals) I would make sure the pool is mixing well for at least 30 min and then retest…. Be suspicious of weird readings that aren’t logical for your pool “norm” until confirmed a number of times

Thanks, I let the pool run another 2 hours after the sock was empty and then let it run another hour before I checked it this morning. I’m going to recheck tomorrow.

 

[BDY]

My cya usually takes 24-48 hours to register after adding, fwiw….

 

[kellyfair]

My cya usually takes 24-48 hours to register after adding, fwiw….

Yep, I don’t even bother to check for a day or two after adding.

I have an AGP, so I use a tall plant hook stuck into the dirt outside of the wall at an angle, to dangle my zip tied skimmer sock with CYA right in front of the return. Even at low speed it only takes a few hours to completely dissolve. If I hop in before it is dissolved, I just swim around, squishing the sock to dissolve the rest.

 

[Mdragger88]

Yep, I don’t even bother to check for a day or two after adding.

I have an AGP, so I use a tall plant hook stuck into the dirt outside of the wall at an angle, to dangle my zip tied skimmer sock with CYA right in front of the return. Even at low speed it only takes a few hours to completely dissolve. If I hop in before it is dissolved, I just swim around, squishing the sock to dissolve the rest.

This is genius!

 

[Bcorig]

So I rechecked today 48 hours later
Initial 40 ppm To get to 70 added 40% of predicted 72 oz.
Today 60 ppm - to get to 75 calculated 32 oz added 40% of that 12 oz
The FCl increased by 40% to 12 since the level at CYA 40 ppm at 60% SWG
So I’m adding 3/4 lb and calling it a day.
Looks like I have a 40% fudge factor whatever the volume of the pool is.
I’m a doctor so I’m always calculating doses for each patient and each patient is different. I’ve been surprised more than once by doses recommended by the package insert. Always start low.
I’m so pleased with the overall condition of the pool since I took over with TFP help its worth the time I’m taking. It’s an easy Chemistry class but I’m graded by the clarity of the water and reduction in tile scaling.

 

[BDY]

Ch, CYA, and salt always aim low. You can only recover with a drain if you overshoot. All the others can be recovered with time or acid.

Great to hear your results! Post your pool in the thread for posterity!
How Clear is TFP Clear?