CYA=0 possible?

[Wes45]

I have not checked my CYA for a couple of months, last time it was 40. I just checked it using a new 8 oz bottle of Taylor R-0013 and it isn't cloudy at all.
I did the test twice, carefully measuring the pool water to the bottom of the label and then filling to the top with R-0013 and shaking, then letting it sit for 30-45 seconds and shaking once again and pouring into the black dot tube.

My other test results are:
TA= 80
Ca =280
Cl =3.0 and I know I need to add some, it's the end of the day
pH 7.4

Is this normal for it to go to 0? Looks like I need to read about adding CYA.

 

[loughps]

I wouldn't say it's "normal" for CYA to go to 0, but you will find several posters (myself included) that have had this happen. In my case, it appears to be some kind of soil bacteria that goes untreated during the winter (I don't try to maintain a FC level while it's covered.) This bacteria can convert the CYA into ammonia. Before you added chlorine, you might have found you had ammonia in your water, but if you're maintaining any FC at all now, it's likely you've used enough chlorine to remove the ammonia.

If you're confident that you truly have no CYA, it would be good to at least bring it up to 20 ppm or so to keep you from losing FC too quickly to sunlight.

What does your water look like? If it's cloudy, or if you're losing more than 1 ppm FC overnight, or have more than .5 ppm CC, you should bring your pool to shock level and hold it there until those conditions aren't true.

The real experts will be along shortly and hopefully say a lot more of the same thing. If you want to read more about this type of problem you can use the google search box at the lower left of the page.

 

[PaulR]

Wes45, since the CYA 40 reading, has the pool gone through a period of high chlorine demand? That is, did you see FC 0 and dump in bunch of chlorine and shortly afterward it was zero again? In that case it would sound like the bacteria problem.

But if your FC has been reasonable all along, and never down to zero, then that's a very unlikely explanation. The bacteria basically won't survive long enough to eat the CYA, if there's chlorine in the pool.
--paulr

 

[Wes45]

I tried to search but if you use cya you get an error message saying there are too many matches.

I had an underground line crack and lost a lot of water back in January and probably got some mud mixed back in the water so might be bacteria or maybe just new water.

I've been dumping a lot of clorox in the pool for the past 2 months (like one 182 oz container per day) and can get the FC to 6 but then it drops to 1-2 by evening. I did the overnight test a few weeks ago and it held within 0.5 so figured it wasn't algae.

Just ran to Leslies and they have a 25% off sale on liquid Instant Conditioner by Natural Chemistry so with the sale it was $25/gal and one gallon should get me close to CYA=20. I just poured it in and will let the pool run an hour or so before trying to test it again. Might go look at Walmart for something cheaper to get it the rest of the way to 40.

Water is clear but not sparkly.

 

[PaulR]

If you search for "cya bacteria" the Google search gets you a reasonable number of hits. But what matters most is how to proceed from here. The liquid conditioner will act quickly, and if it holds then you're good.

One other factor regarding the CYA test in particular: it works better if the water sample is no colder than room temperature (70-ish). If your pool temp is still in the 50s that will slow down the chemical reaction in the test and it can read low.
--paulr

 

[duraleigh]

Wes, an autofill can sometimes cover up an undetected leak (which would bring CYA to zero) but I assume you don't have an autofill.

 

[Wes45]

Thanks for the replies, my pool water is 72 degrees and I have an auto filler. I checked my CYA and it now reads 20 so will pour the second bottle in tomorrow.

I will turn off the auto filler to make sure the repaired joint from January is still holding.

 

[Wes45]

Once again I learned how things can get out of control by not regularly testing your CYA level, once every 3-4 months is definately NOT the way to go! BTW, I wish I had known about the CYA eating bacteria a few years ago when my CYA was 150!

It cost me $53 to go from 0 to 40 using the liquid from Leslies and thankfully that was 25% off. My pool's demand for bleach has dropped off significantly. I've probably wasted over $50 in bleach since January when I had my major leak.

I picked up an 8 oz bottle of Taylor R-0013 from a local pool company for under $10 so I should have enough to check my CYA levels regularly from here on out. I assume monthly would be good enough?

 

[PaulR]

Given the history of your pool, I might be inclined to test monthly as well. In a pool with no significant CYA trauma, people seem happy with once every 2-3 months.
--paulr