CYA dropped, WHAT?

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esim13

esim13

0
Oct 31, 2009
324
Denham Springs, Louisiana
hey guys and gals,
So I've been trying to keep pool at shock level these last few days as recommended on earlier post. It's been tough - I teach Kindergarten, it's the last few weeks of school, everything going on, sinus infection to boot - I'm exhausted. BUT - Today is Friday!! which has given me a few bits of energy and I'm ready to tackle the pool again.
I tested today around 5:00, sun still out, pool half in shade. I plan on testing again tonight after dark and doing another overnight test. As for today, here's what I got
FC 6
CC 0
pH 7.4
TA 120
CH 140
CYA 30 (What?? I tested this Monday and it was 60!!)
So what's with that? I ran out of CYA testing solution, ordered more, it came in today and I just tested with it. I did the test 4 times! I got 30 and close to it each time. Am I that insufficient in testing CYA? Could the original R-0013 have had problems? Is the new R-0013 that much better? Am I good to go with CYA at 30 when Monday it was 60?

Does everything else look on target?
Thanks!
 
If you're confident of your original reading, the most common reason for CYA to drop is water replacement. Have your been backwashing your sand filter? Also an autofill system can mask a leak. As it keeps topping off the pool, the dilution will result in a lower CYA number.
 
Have you been backwashing lots or replacing water?

When you did the CYA test before, are you doing it now under the same lighting (time of day, etc) as before?

I suggest you test again this weekend and if you still get 30, that's what I'd go with.

There are so many variables with CYA testing (temp of water, time of day w/lighting, etc) not to mention starting with a +/-10 ppm. So, consistency in how and where and when we test is important.

Your numbers look fine. You'll repost after the overnight FC loss test?
 
I have not backwashed, have not changed the water, and do not have an autofill system. I'm thinking it has to be my error somehow. New contacts maybe... :) If I remember correctly I tested it around the same time of day on Monday. I usually do it within an hour of getting home. I'll retest it again this weekend.

I tested FC again around 8ish, it dropped to 5. I've added 9 cups of 6% to reach high end of target and now I'm at 8.5. I'll recheck in the weee hours of the morning and post results.
 
yep, outdoors, back to the sun. Last weekend it was cloudy, drizzling rain and just nasty. The pool was filled almost to the top of the skimmer with rainwater. Yesterday, I barely backwashed, just for a second to get a few bubbles out of the pump basket. I don't think it could have dropped the water by much nor the CYA. It was just a quick on off. At any rate, I'll do the overnight FC and I'll retest CYA tomorrow or Sunday.
Thanks everyone!!
 
FC held overnight :whoot: 8.5 when I went to bed, 8.5 in the wee hours of the morn!
I retested CYA just out of curiosity and it is still roughly 30-35. It's cloudy today, a bit overcast but still bright out. I was thinking of backwashing this morning, pressure's up a bit and I didn't backwash after I shocked earlier in the week. How much will this affect my CYA level, ya think? I don't have any stabilizer but I do have some leftover pucks from last year. What do y'all think - should I add some to help raise CYA a bit?
 
Backwashing once shouldn't have much effect on the CYA level. Backwashing over and over through a whole season has a noticeable effect on the CYA level.

Since it is early in the season, you will want to raise your CYA level to around 50. Otherwise it will fall below 30 (get too low) at some point during the season. Using some leftover pucks is one way to do that, though it will only raise CYA very slowly, and you need to watch to make sure that it doesn't reduce the PH too much.
 

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esim13,

Hello, I saw that we are neighbors so I wanted to say hi! We have enjoyed TFP so much. They have helped us, get and keep a clear, "Trouble Free Pool". Because we live in the same area we most likely experience some of the same conditions with our water. Anyway, sorry to jump in on your post here. Oh and BTW our CYA stays around 40.

Tim
 
Just a quick hello from down the river a bit. My AG pool will be finished tomorrow (I hope), but it's my second one so I'm not really a newbie. 3-inch tabs in a floater will raise CYA and FC, but your FC is high enough already at 8.5 so definitely no more bleach while the floater is working. I'd go with one tab until the FC dropped to around 5 or so, then add the second. Or you could just get some CYA and do the sock in front of the return jet thing.
 
I put 2 pucks in Saturday then another one in on Sunday. I tested today and here's what I got:
FC 5.5
pH 7.6
TA 100
CYA 50
Could the CYA have risen in that short period of time? Should I take the 3 pucks out? (one is almost dissolved, there others are just a little smaller) I haven't added any bleach or pucks since Sunday. thanks!
 

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