Super High CYA

[b0m8ad1l]

I recently moved into a new house that has a pool (18,000 gal/gunite). The previous owners of 10 years used all the pool store chemicals, predominately trichlor tabs for sanitizing. I got my new Taylor test kit to start getting the pool ready to open. It turns out that the CYA is off the charts. On the small taylor test tube, the water level doesn't even get anywhere close to the numbers for the CYA test (100,90,80, etc...). The water level is just above the 1.8 mark on the side of the tube. Is there a test that I can do to determine my actual CYA level? What does my chlorine level need to be in order to be effective? I really don't have the money to drain and refill the pool at this time. What is the best thing that I can do here?

FC: 6.5
CC: 0
pH: 8.0 (just added 1 gal of Muriatic acid to lower to 7.0). With the plan to aerate to raise the pH and lower TA).
TA: 140
CYA: off the charts

Thanks for the help guys. I love the site. It has been great resource for this new pool owner.

 

[linen]

Welcome to tfp, b0m8ad1l

How does your water look?

To find out what your cya level is, mix 1/2 pool water and 1/2 tap water together than use that to fill the bottle half way, and do the rest of the test the same. When you get your result, multiply it by 2 and that will be your cya level...unless this result is still above 100 before multiplying...then your cya is higher than 200 ppm. Let us know your results and we can go from there.

 

[b0m8ad1l]

In my limited experience, I think that the water looks perfect.

I followed your directions and diluted with 1/2 tap water and the test water is just a hair below the CYA 100 reading. So it looks like my CYA level is a little over 200.

 

[jay87]

Here's the chlorine cya chart

www.troublefreepool.com/pool-school/chl ... hart_shock

As you can see the FC and shock range will be very high with a CYA of 200. Even halving it to 100 will make it more manageable

 

[duraleigh]

100 ppm CYA is "better" but really still not manageable. Your target for a manually chlorinated pool should not exceed 50 ppm.

 

[linen]

Duraleigh beat me to it, but here was my response...

Do you know what the cost of your water is? Often times it is less than you would think. Also, if your municipality charges a sewer fee with the water fee you may be able to contact them and get that waived for the pool refill.

As Jay87 pointed out, dealing with a cya of 200 will be very difficult. I am not even sure I would know what FC level to maintain at 200 ppm (or that the poolcalculator.com suggested level can be trusted up there), so from my perspective you will have to drain regardless. Managing at 100 can work but you need to be very vigilant and hold your FC at a higher level to prevent algae. I would bite the bullet and lower down to a manageable level of ~50 ppm.

 

[Richard320]

When I took over my pool, I got somewhere between 220 and 240 on CYA, because the previous homeowner and his inept pool service used pucks exclusively. There were a few other deficiencies, but that's another topic. I was under water restrictions that year, so draining was not an option. I would have ended up with a hefty bill, and a water restrictor installed on my meter at my expense...

It CAN be maintained with astronomical CYA, but it is not easy, nor would I recommend it. Just for starters, the pH test will always be iffy, because the FC level has to be kept so high. And the color block quick test for FC is useless. The only way to test FC is the FAS-DPD test every day.

By watering my lawn with pool water then refilling, and capturing rainwater from the gutter downspouts I was finally able to get CYA down to 40ish in about a year. It's much easier to maintain with low CYA. I can eyeball the OTO test and know if I need to add bleach or not, the pH test is accurate, and I have enough breathing room on the CYA that I can use pucks when I leave town.

 

[b0m8ad1l]

Thanks for all of the help guys. Richard320, that sounds like exactly the situation that I'm going into. I think that I will have to struggle through this first year like you did, until I get the CYA to a manageable place. Can you elaborate a little more on how the pH test will be iffy?

 

[Richard320]

Thanks for all of the help guys. Richard320, that sounds like exactly the situation that I'm going into. I think that I will have to struggle through this first year like you did, until I get the CYA to a manageable place. Can you elaborate a little more on how the pH test will be iffy?

The color on the pH test gets messed up when FC is higher than 10. So just aim for the middle and you should be okay.

 

[chem geek]

Do you know if they were using algaecides and if you still have those available to you? If so, then that's a possible way you can manage for this year as you wait for water dilution (from winter rains or other sources) to reduce the CYA level. I'm not suggesting buying algaecide, since you can just maintain a higher FC level instead. I'm saying that if you've already got it, then you can use it (depending on what it is -- let us know since some are better than others) and that may let you have a lower FC than we normally recommend which would save you some on chlorine and also help have the pH test be valid.

 

[b0m8ad1l]

I do not think that I have any algaecides on hand. I will check on that when I get home tonight. I am using borates though. I've added one round of Borax to an estimated 30 ppm and am waiting on my test strips to arrive to before I add more. I then plan to get the borate level up to 50 ppm.

 

[frustratedpoolmom]

How does the water look? Is your FC holding? Its super-difficult to manage FC with CYA that high - the key is preventing problems from developing - it could happen super fast before you can do anything to stop it. So be diligent - and start researching water replacement options... Good luck!