240 CYA?!?

[brucek2]

Relatively new pool owner here. Moved six months ago, house came with pool and existing pool service. Water has looked and felt good all that time although I have no measurements. I did notice there was/is white scale at the waterline since I moved in.

Pool service quit a couple weeks ago. I figured I could take over myself, how hard could it be ;-). After several days procrastination ordered the Taylor 2006 test kit which being I'm in Hawaii came just a couple days ago. I also filled up the existing but empty Hayward CL220 chlorine feeder with trichlor tabs, which I now fear was a big mistake.

Pool still looks clear and sparkly to me. But here's my first ever set of measurements:
PH 7.8
Calcium >400
TA 170
CYA 240 (measured by diluting 2:1)
FCL 11.5
CCL 1.0

So I'm thinking I need to drain and replace at least half the water, maybe twice over. Before I do that I've got a couple concerns:

1. Being that water still looks good, should I be concerned that maybe I'm just screwing up the measurements? I've done the CYA test 3 times over and always with the indication that I'm way over 100. It seems like a straight forward test but are there common errors?

2. Is it possible I sent the CYA this high just by the single load of that chlorine feeder? Or was it maybe already pretty high even before but there was just no way for me as a pool user to know?

3. Anything else I need to be concerned about before I replace some of the water?

Thanks for any suggestions!

 

[JasonLion]

Welcome to TFP!

1) The CYA test should be done in sunlight, with the view tube shielded from direct sunlight by your body. Using artificial lighting can cause false high readings. Also, the black dot should be completely gone, no hint it was ever there even if you stare at it for several seconds.

2) It must have already been high.

3) The main thing is to not drain the pool below the local water table. If you are unsure of how deep that is, it is better to err on the side of caution.

 

[Richard320]

Welcome!

Well, you're in a heap o'deep with that CYA level. Been there, done that, don't wish it on anyone. It can be maintained with CYA that high - I've done it out of necessity due to water restrictions, and I suspect water is precious where you are. I wasn't able to drain and refill for quite a while. My relief came from rain. I diverted the gutter downspouts to the pool.

If you are stuck with it, you'll need to maintain really high FC levels, but since you have the K-2006 you can actually measure the FC. I'd order refills now, because you'll be burning through the R-0870 & R-0871 at an alarming rate.

 

[brucek2]

Thanks Jason! My measurements were in sunlight but not sure whether I shielded the view tube using my body. I'll try again tomorrow just to be sure.

I'm about 600 feet above sea level and half way up a steep hill, so I'm thinking I must be well above any water table? I'll ask around locally just to be sure. Thanks for the tip.

 

[brucek2]

And thank you Richard as well. I was already thinking I needed to reorder CYA test materials and will add those other ones too.

We are entering the "rainy season" here although overall its still pretty dry compared to many places. Interesting idea about feeding gutters to pool, sounds like something I should at least look into. I think only some of them will be practical to tap though.

 

[brucek2]

Just got this email reply from the former pool service guy:

"The CYA level has been on the high side. That is only the chlorine stabilizer level. It is not going to harm anything being on the high side. To lower it, you have to drain water from pool. Either from frequent backwashes or dumping water all at once and refilling. Don't fill the chlorine feeder up full. I only add one tablet (3") per week to the feeder. I might also add one tab to floater in the trough."

Its comforting having confirmation the CYA really is high. I think I'll go with the sentiment here that it should be much lower vs. his "not going to harm anything" approach, although to his credit I really have enjoyed the water all this time. Maybe sometimes ignorance is bliss

Also good to know the feeder is not supposed to be full. Makes me wonder why it can hold so much -- or maybe this same model is meant to support 200,000 gallon commercial swimming pools along with my much more modest residential one?

 

[Bluechip]

2 pucks a week would only add about 6 ppm of chlorine. Not nearly enough if your CYA is that high. Really not enough under any situation. Also it would be adding an additional 4 ppm of CYA per week.