New member with CYA woes

[ducc]

Hi All,

I'm happy to be a part of this forum and its wealth of information. I've spent the last week lurking the site (and Reddit), and I took delivery of a TF-Pro this week. I've watched countless videos and read the instructions several times, but I'm a full-on rookie at this through and through.

That said, I tested CYA today, and it was through the roof. I was under the 100ppm marker by a good margin. I retested with the tap water combo and barely hit 90 (oh, and this is ~90 before doubling it. Yea). I took a shot at the FAS-DPD too, and the water barely turned pink. It took one drop to go clear. I have no idea how my pool doesn't look awful right now. I pulled the plug on the rest of the tests (pH, TA, CH) because I'm not sure how much all that matters considering my CYA numbers.

I'm concerned about a partial drain while we're close to hitting 115+ degrees here in AZ. I've read that RO is an option. What's the consensus on this procedure to lower my CYA? There are a couple of mobile RO shops in town, but I haven't contacted anyone yet.

Any input is much appreciated!

Additional details (not in my signature):
• Maintained by a pool service company for 10 years (uses nothing but tabs and shock) that I'm trying to part ways with
• Pool was last drained around 4 years ago
• Tons of direct sunlight and under a massive Eucalyptus tree (city-owned) that rains down leaves and seeds (especially this time of the year)

 

[ajw22]

Welcome to TFP.

Read about our No Drain Water Exchange in Draining - Further Reading

I think the Water Exchange will cost less and use less water then RO.

 

[ducc]

Welcome to TFP.

Read about our No Drain Water Exchange in Draining - Further Reading

I think the Water Exchange will cost less and use less water then RO.

Will do - thanks for the suggestion and link!

 

[Mdragger88]

Welcome to TFP
Sorry we’re meeting this way
Do the ch test.
Also test the ph, ta, & ch of your fill water to get an idea of what you’re working with & record those.

As @ajw22 mentioned the no drain exchange is your best bet.
Get ready & until you’re ready you need to get the fc up with liquid chlorine so it doesn’t go south on you.
Use
PoolMath to calculate amounts.
.... "Min FC" is 7.5% of the CYA level
7.5% of 180 = 13.5
.... "Target FC" is 11.5% of the CYA level
11.5% of 180 = 20.7
.... "Shock FC" is 40% of the CYA level

 

[ducc]

Welcome to TFP
Sorry we’re meeting this way
Do the ch test.
Also test the ph, ta, & ch of your fill water to get an idea of what you’re working with & record those.
View attachment 513095
As @ajw22 mentioned the no drain exchange is your best bet.
Get ready & until you’re ready you need to get the fc up with liquid chlorine so it doesn’t go south on you.
Use
PoolMath to calculate amounts.
.... "Min FC" is 7.5% of the CYA level
7.5% of 180 = 13.5
.... "Target FC" is 11.5% of the CYA level
11.5% of 180 = 20.7
.... "Shock FC" is 40% of the CYA level

Thanks, Mdragger88! I imagine my CH will be well out of range too, considering water here in AZ. I'll test later today.

 

[ducc]

So, I wound up using an RO service, and wow, did it wipe the slate clean!

My CYA was close to 180 and is now sitting at 15 or possibly lower (yikes)
My CH was close to 1000 and now is around 75 (uh oh)
FC fluctuates from 0-1ppm (no surprise considering my lack of CYA)
pH is 7.8 (RO guy mentioned keeping it on the higher end due to my low CH. )
TA 80

I was told (by the RO company owner) that my CYA should gradually rise in 7-10 days because, according to him, it's still in the pool (maybe on the surfaces?). It's been about 4 days, and I can still fill up the tube and see the black dot. I'm willing to ride out 10 days, but I wanted to get some expert takes here on this. High CYA got me into this RO mess, so I'm gun shy about adding a bunch of stabilizer, but I do understand its importance. In the meantime, I test my water twice a day and add liquid chlorine as needed.

I'm also hesitant about adding Calcium because I lose a ton of water daily to evaporation here in AZ, and our water is notoriously hard in the SW. I would rather let nature take its course, but I'm a far cry from the 250 target. Is a slow rise in CH a bad move?

Appreciate any insight! I never thought I would get a pool chemistry obsession, but it looks like it's heading in that direction. Look forward to learning more from everyone here.

 

[wireform]

I never thought I would get a pool chemistry obsession, but it looks like it's heading in that direction.

I found out it's very contagious

 

[mknauss]

it's still in the pool (maybe on the surfaces?). It's been about 4 days, and I can still fill up the tube and see the black dot.

The CYA is in the water, not in the plaster. Why they think that, who knows. Add 20 ppm worth of CYA and test 24 hours after it is fully dissolved from the sock.

The low CH is a threat to your plaster. I am no fan of adding calcium to water here, but you might consider using cal hypo to chlorinate for a couple months to push the CH up a bit quicker.

Then consider using softened water for fill water once CH rises to 300 ppm or so. Do you have a whole house water softener?

 

[ducc]

The CYA is in the water, not in the plaster. Why they think that, who knows. Add 20 ppm worth of CYA and test 24 hours after it is fully dissolved from the sock.

The low CH is a threat to your plaster. I am no fan of adding calcium to water here, but you might consider using cal hypo to chlorinate for a couple months to push the CH up a bit quicker.

Then consider using softened water for fill water once CH rises to 300 ppm or so. Do you have a whole house water softener?

Thank you for the suggestions, @mknauss! The RO guy mentioned he had customers complain about increased CYA despite modest additions they made. His conclusion was that residual amounts are still present... somewhere.

I'll experiment with the cal-hypo too. Messing around on pool math, it doesn't seem to add much calcium per treatment, so I can ramp up slowly.

No water softener in the house, unfortunately.