CYA off the charts

[Magellan]

Hello Folks,

First time posting newbie here, but been lurking for a while. Typical in-ground gunite pool with white plaster, 18 years old, 18,000 gallons, 3 foot shallow end to 6 foot deep. I have owned the home since the pool was built. Where I live days at 100 degrees plus are not uncommon June through September. My chlorination all along has been 3" pucks and shock from Home Depot and/or Lowes.

Started having problem with algae on the walls last year. Shocking and sweeping help, but chlorine level drops fast and it comes back quickly. Reading this website, I bought myself a TFTest kit TF-100. The markings for the CYA test go from 20 to 100, with the scale getting smaller the higher the number. The dot is no longer visible when the level is still about 1/2" below the 100. So I'm guessing a CYA of about 140.

All of this tells me I need to drain the pool. I did drain it about halfway last year to replace the light. Before that it has never been drained. So if my CYA is still so high, is it possible it was even higher before? The idea of draining it completely scares me. I don't know if I have a hydraulic valve and visions of the pool popping gives me nightmares. Also, most of my neighbors have pools and I have never heard of them draining their pools.

So, my questions are 1) Does a CYA reading this high for a pool with half of the water from the original fill 18 years ago and half from last year seem reasonable? 2) Is it safe for me to completely drain the pool? and 3) If changing the pool water is a normal part of pool maintenance, how come I have never heard of any other pool owners doing it?

Thanks in advance for any input.

 

[mechanikmike]

I am just as new here as you are but after reading a bunch of threads on this site you sound like you are in the same predicament as me, my pool liner was replaced last year, all new water, the pool guy did the original chemicals and then sold me pucks, ends up the pucks and the granulated, not the shock but regular granulated chlorine, all add CYA to the water which in the one season and start of this season my CYA is already 80 from the pucks, I will have to start swapping water, I'm definitely a noob but as far as I know swapping water isn't normal, but if you use the pucks and then start actually testing things to finally stop the algae then swapping water will be in our future. I'm glad I came across this site when I did

 

[domct203]

Hello Folks,

First time posting newbie here, but been lurking for a while. Typical in-ground gunite pool with white plaster, 18 years old, 18,000 gallons, 3 foot shallow end to 6 foot deep. I have owned the home since the pool was built. Where I live days at 100 degrees plus are not uncommon June through September. My chlorination all along has been 3" pucks and shock from Home Depot and/or Lowes.

Started having problem with algae on the walls last year. Shocking and sweeping help, but chlorine level drops fast and it comes back quickly. Reading this website, I bought myself a TFTest kit TF-100. The markings for the CYA test go from 20 to 100, with the scale getting smaller the higher the number. The dot is no longer visible when the level is still about 1/2" below the 100. So I'm guessing a CYA of about 140.

All of this tells me I need to drain the pool. I did drain it about halfway last year to replace the light. Before that it has never been drained. So if my CYA is still so high, is it possible it was even higher before? The idea of draining it completely scares me. I don't know if I have a hydraulic valve and visions of the pool popping gives me nightmares. Also, most of my neighbors have pools and I have never heard of them draining their pools.

So, my questions are 1) Does a CYA reading this high for a pool with half of the water from the original fill 18 years ago and half from last year seem reasonable? 2) Is it safe for me to completely drain the pool? and 3) If changing the pool water is a normal part of pool maintenance, how come I have never heard of any other pool owners doing it?

Thanks in advance for any input.

Welcome to the forum!

You need to do an extended (diluted) CYA test to get a better idea of how high the CYA is. The scale is not linear, so we really can't guesstimate the amount.

Pool School - CYA

 

[randytsuch]

1. Seems reasonable to me
2. Should be ok. Draining is a problem if there is water in the ground, think the south may have this. The pressure from the ground water can pop a pool shell out of the ground if the pool is empty. Even with the rains this past winter, I can't see it being a problem in Cal. But you may not need a complete drain, do the diluted CYA test and see what you get. Although I once drained my pool, and the plaster job that the previous owned had done was so bad the plaster started coming loose in hunks after I drained the pool. The water was the only thing holding the plaster in place it seems.
3. People are stupid?? Seriously, I didn't know how to care for my pool correctly until I found this place. And the percentage of pool owners that use TFP is probably frighteningly small.

 

[domct203]

Changing water should never be a part of regular maintenance. Unfortunately many pool owners are oblivious as to what they are actually putting in their pool (as was I before I found TFP). Years of blindly following pool $tore advice left me with a pool that I didn't even want to go into because of cloudy water and reoccurring algae.

Once I took the time to read though the pool school articles here, as well as the great advise given here, I can proudly say that my water has been clear as glass for the third season in a row, and I have never enjoyed my pool so much!

It's all about reliable and accurate testing, something I lacked until I bought a proper test kit and started testing myself.

 

[Pool Amateur]

I do not think draining a pool is considered normal maintenance by most people but that is why algae is such a big problem, and why we go to pool store and get sold chemicals to lower phosphate (so the algae does not have anything to eat), and algaecide to prevent growth, then because of metals from those we need sequesterents, clarifiers and flocs, ect. Does this sound like normal pool maintenance? But here is the big catch, CYA buffers chlorine so not as much of the hypochlorous acid (the disinfecting form of chlorine) is available to disinfect or sanitize the pool. Therefore clear water without algae may not necessarily be safe to swim in. But this is how I think most pools are maintained.

The idea of draining it completely scares me. I don't know if I have a hydraulic valve and visions of the pool popping gives me nightmares

There is a way to exchange most of the water without draining, called the "sheet method" or "tarp method" here is a thread by Smartjack when he did it post #62 has a link to pictures and videos, day 2 has good videos.

 

[Magellan]

Thanks for the replies. An extended CYA test is definitely in order. And the tarp method of replacing the pool water is a great idea. So I know what I need to do, there is just one problem. 108 here yesterday, 105 today and tomorrow. Similar next weekend. Changing and restarting the pool water means several days without swimming. In this heat the thought of that is hard to accept. I have been dealing with this problem for a while. I have switched to non-stabilized chlorine and will nurse a little longer until we get past this unreasonable heat.

 

[domct203]

If you need to put off the drain and refill, that is understandable, but I strongly recommend you do the extended CYA test ASAP so you know what FC level you need to maintain to avoid algae, or you will not be swimming because of algae/bacteria instead of not swimming because of drain/refill.

Minimum safe FC level is 7.5% of your CYA level. Target FC is 12-15% of your CYA level.