CYA

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Boburk

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Jul 25, 2015
57
Burkburnett/TX
Done a lot of reading lately due to pool problem this year.

This is my 7th year with the pool. Had an algae bloom I could not kill. Went through 100 lbs of chlorine, and a bottle of algaecide. My pool is eating chlorine.

Anyhow...took water to Leslie's. They told me my stabilizer was high. Sold me a $60 cluture to add to my filter. No help... When retested they told me my CYA was 160. Drained half the pool and refilled.

Found this site, bought my $100 pool test kit. Checked CYA and am getting a reading that is off scale too high. Drained half my test bottle and filled back up with tap water and tested again. I got 85ish. Did the test twice with similar results. So I take it my CYA is 170 correct? Nothing can throw this off? I am back to draining part if my pool and refilling again?

Why would my CYA be so high this year? Due to a drought we had, i used rain water to fill my pool last year. Any way this could cause it? Used mostly tap water when filling after the half drain I did this year.

Sean
 
Boburk said:
Done a lot of reading lately due to pool problem this year.

This is my 7th year with the pool. Had an algae bloom I could not kill. Went through 100 lbs of chlorine, and a bottle of algaecide. My pool is eating chlorine.

Anyhow...took water to Leslie's. They told me my stabilizer was high. Sold me a $60 cluture to add to my filter. No help... When retested they told me my CYA was 160. Drained half the pool and refilled.

Found this site, bought my $100 pool test kit. Checked CYA and am getting a reading that is off scale too high. Drained half my test bottle and filled back up with tap water and tested again. I got 85ish. Did the test twice with similar results. So I take it my CYA is 170 correct? Nothing can throw this off? I am back to draining part if my pool and refilling again?

Why would my CYA be so high this year? Due to a drought we had, i used rain water to fill my pool last year. Any way this could cause it? Used mostly tap water when filling after the half drain I did this year.

Sean
Click to expand...

Welcome to TFP!

I'd say that you are close to what your CYA level is, with the fact that the test is somewhat subjective. So, yes, there will be another drain/refill in your near future.

Tap water and rain water do not contain CYA. Rain water -- aside from having a lot of dust in it -- is actually better for filling your pool.

You mention using 100lbs of chlorine. Is it safe to assume that this is trichlor pucks? If it is, that would be why the CYA got so high. Dichlor and trichlor both add CYA to your water only differing in the amount they add. This is why we recommend liquid sources for your pool's sanitation/algae control.
 
Bucket says calcium hypochlorite. It was in granule form. I could put 4-5 lbs in...test a day or two later, and have zero chlorine.

I used a product called green to clear to kill the algae. That worked but left my water milky. Drained my pool halfway afterward. Still won't hold a chlorine level. Has a slight green tint now.

Found this site and bought some bleach to start to figure the dosage amount out. Poured a gallon in last night and the chlorine level went from zero to 3 PPM. That was about 7pm. Got the new test kit out this morning started testing. Chlorine is at zero. Alk is 80, CYA as above. Stopped there and have the back flush on again to drain some water out.

REALLY want to SLAM it this weekend and start swimming soon. Water bugs and frogs (no joke). Relatively no leaves or other stuff (pine needles) in it. I have a pool bot and it is running now to clean the dead algae from the bottom.

Pool is concrete above ground. Local pool place estimates 14,000 gallons.Draining half takes 12 plus hours to fill.

Sean
 
Boburk said:
Done a lot of reading lately due to pool problem this year...

Found this site, bought my $100 pool test kit. Checked CYA and am getting a reading that is off scale too high. Drained half my test bottle and filled back up with tap water and tested again. I got 85ish. Did the test twice with similar results.
...
Sean
Click to expand...
Just double checking on your description of the dilution procedure... When you say that you drained half the test bottle, does that mean you drained half of the water/reagent mix, and then filled with tap water? That would not be correct, although I suppose it might give you a similar reading in the end.

What you want to do is dilute your water sample 50/50 - e.g. by mixing a cup of tap water with a cup of pool water. Then take your test sample from that diluted water, and then combine the water sample with the normal amount of CYA reagent according to the kit instructions.
 
Hello Sean. I suppose either ay you slice it, somehow someway your CYA grew incredibly high from a pool store product. We know regular bleach won't do it. All you can do now is what you've already learned from TFP and your own test kit - partial drain. That really is the only way to reduce that CYA, and by now you probably know to save your money for bleach and not those pool store miracle products.

At the very least, try to get your CYA down to about 50-ish so you can manage the SLAM like you want to this weekend. Don't forget to have your PH around 7.2 as well before you start SLAMming. I know it stinks to SLAM during this TX heat when all you can think about is a good swim, but hopefully you'll get that wrapped-up soon. Best of luck.
 
You will find much better results with a "healthy" drain as opposed to many tiny ones. CYA doesn't dilute or go down over time or by adding water. Only when that water is actually removed does the CYA go down. Since you are extremely high based on a diluted test, I would drain some, then test CYA again. While 30 is ideal for a SLAM, you can be a little higher. It's your call. But I would get it down to at least 50-60 if possible.

If you look at the Pool School - Chlorine / CYA Chart, you will see how high your FC needs to be based on the CYA. You can also use the Poolmath calculator to plan in advance how much bleach would be required to increase your FC.

I hope that helps you plan accordingly.
 
Boburk said:
If I just drain 1/4 to 1/3....so i can get this going this weekend...then follow the procedures here (using bleach, not pool store products) and try to lower the rest of the CYA over time...how big of a mistake would I be making?

Sean
Click to expand...
While it might be possible in theory, it becomes quickly impractical to try to slam with CYA levels over 100. It's generally recommended that you get them below 80 before beginning a SLAM, and even that will try your patience. Imagine counting over 60 drops of test reagent every time you run FC... Plus you end up wasting water, since you have to dilute that, then drain some and dilute that, then drain some and dilute that... It's better to just do it all at once, or in bigger chunks anyway.

I went through this exact problem when I moved in here - the previous owner did whatever the poolstore told him to, and my CYA was over 150 and the pH was was so low I had to borrow an expensive field meter from work to measure it - turned out to be 4...

I bit the bullet, bought a pump, and got my pool diluted down and my CYA is about 50 now. Things are so much easier to manage once that's fixed.
 

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OK...back to pumping it out. If I drain half again, I should wind up with 80 CYA. I will start with that, and might start the SLAM as it fills (when close to done filling).

My thought with waiting to get the CYA down was that I could do it while back washing the filter, or when it rains (I have one downspout I can direct into the pool, and two that go into a 2500 gallon tank). I wish I had more accurate numbers from the pool store before draining last weekend.

Sean
 
15 Gal will get your started. Depending upon your pool gallons and starting FC, you may need 3-4 gallons just to get there initially. Use the Poolmath calculator to confirm though. After that, the sun and algae will eat-up FC and you just have to replenish periodically. You'll learn soon about how much and how often to add bleach based on your test results. Initially, you will only need to keep checking the FC, so save your other reagents for later. Goood luck.
 
This is probably a stupid newb question...but when testing CYA after refilling the pool, I get to about 65 and the dot is obscured. If I move my head around, I can see its contrast. I added more up to about 60 and if I moved around, I could see the dots contrast again. Was 65 my level, or is it actually under 60?

Sean
 
This is where our mind (and OCD) tends to play tricks on us. :) I does for me. That's why when I do the test the first time, I immediately pour it all back to the mixing bottle, shake it, pour it back to the tube, and try it again. Then I do it 3-4 more times if I need to so I have a consistent reading. With the tube at waist level, I start squeezing the mixture into the tube. I don't stop until the dot is gone with the sun at my back. I don't squint my eyes or move around, just stay still. Then I repeat the test as many times as I need to until I have a couple repeat readings or have it narrowed down really close. After a few times, you'll get in a "groove" and get comfortable. If you are absolutely splitting hairs between readings, round-up or down from 5 (i.e. 64 or less = 60, or 65 or greater = 70).
 
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