Need your expertise...

[pepsiholic]

I opened and balanced this spring without a problem, but things are driving me crazy right now. I have added enough cya, about 2 weeks ago, to get to 50 (or so I thought), but when I tested today it was only ready 35. I tested last night and my other numbers were:

FC 5.5
CC 0
TC 5.5
ph 7.5
TA 110 So I added enough bleach to get up to 8, to allow my 2.5 burnoff I usually have during the day. Today, I got in and vacuumed and swept, it wasn't very dirty, but I did it anyway. So... when I checked my chlorine tonite, imagine my shock when this is what my numbers were:

FC 4
CC 1
TC 5
cya 35 I always keep my chlorine on the high end so even at a cya of 35 it's never went below 5, so I guess what I'm wondering is should I bump up my cya again (I have had to add water to the pool due to evaporation), could that be why my cya never seems to raise? I went ahead and started the shock process, but I am thoroughly confused right now. My water is still very clear and very sparkily. Thanks so much to you all and I look forward to your advice :-D

 

[woodyp]

CYA doesn't evaporate. Its gettin' hotter outside..pool temps are rising...........and thats probably where your extra FC is going. Also, adding any "extra" FC over what your CYA level suggests in the tables in pool school just burns off faster. You just don't have enough CYA to 'hold" the extra in. Notice how fast that shock level of FC drops after you're thru shocking?

 

[jmborchers]

Because your test shows your free chlorine went into combined chlorine I would bet you stirred up something during your cleaning. If FC evaporates it doesn't create CC from my understanding. So from what I see by your supported data is .5 FC evaporated or worked against the 1 ppm CC. I think if you keep on top of the FC level you'll be okay if the CC 1 ppm is a one time event. If it's not then you'd need to investigate why.

 

[pepsiholic]

Thanks, then should I go ahead and add more cya? I'm guessing my opening number must not have been correct at 35, must have been more like 15-20.

 

[jmborchers]

I think if you repeat test at 1 CC tomorrow (after 24 hours) you'll need to do something about it. As a scientist by trade we never worry about a single data point beyond the specification we worry about a trend forming. If you see a trend forming in the wrong direction then I would slam it.

Mine is a temp pool I'm still sitting under 30 CYA (about 15 actually from Pool calc now for the season). I'm losing 1 FC over 24 hours. Your CYA is not too much under the target (I don't see evidence of SWG from your post). What I would want to do is leave room to expand my CYA higher during the season if I suddenly needed to go away for an extended period and I couldn't monitor chlorine level. Then I could toss in a stick and I had room to move CYA up while the pool auto chlorinated. My target CYA is also around 35 which will allow me two weeks vacation away from the home while my pool self chlorinates. If you aren't going away from the pool this summer than I would go to the recommended target if not I would leave it where it is. It's not too far off.

 

[pepsiholic]

Ok, thanks. I'll keep an eye on it for a few days and see what happens. It is in full sun from daybreak to dusk and I have always lost 2.5 daily, so to lose 4 like that just seemed like a lot. I probably worry to much. My friends and family say they have never seen a pool as clean and sparkily as mine, so I guess I'll just keep doing what I do, reading this sight with an occasional question.