Everything is good, but....

[Gretchen]

Background info: New liner and water this season. 35,000 gal. vinyl in-ground pool. It is a garden pool so it has both sun and shade. This mornings numbers:

TC: 3
FC: 3
Ph: 7.4
AK: 170
CYA: 40 at last test (out of reagent!) and we've been running on bleach ever since so there should be no change.

The water is clear and we have no evidence of scale or anything. No problem, right? BUT - we're running through a lot of bleach this year. It seems to lose chlorine pretty fast for the CYA numbers we have. We've had the pool up and running for a month now. At first, I kept my urge to pour everything in the pool and make it PERFECT under control by testing every other day. Now things are closer to where I'd like them to be (I think) so I'm back to every morning.

The alkalinity was quite high at first test with the new water. Off the charts. We have two pretty strong outlet jets and they were directed up, so we have a constant ripple at each side of the pool. I haven't lowered the Ph as far as recommended but it is still doing the trick over time; a week ago it was 180 so it is still dropping. I'm assuming this is also why we're using more chlorine than usual?

I'm a firm believer in not fixing it if it ain't broke but still I'd like to know why!

[aylad]

This year we've seen a lot of cases where CYA was high at the end of the year and very low at the beginning of this year, which meant the CYA broke down into ammonia and caused a huge chlorine demand. Could this be the case with your pool?

Otherwise, I would test for chlorine at night and again at sunup, and if you've lost chlorine overnight, then shock the pool.

Janet

[Gretchen]

I'd found some of those threads but our case is different. We lost all our water over the winter when our old liner finally gave out, so this is fresh water as of 4 weeks ago. I added 4 lbs of CYA through the skimmer and ran two feeders of tri-chlor pucks to take the CYA up to 40 before I began on bleach. I'm testing in an hour and will again in the morning. What level should I look at keeping? Since the pool is in a garden we want to keep the chlorine low if possible. How low is too low, and what would be shock level for the rest of my readings?

[aylad]

Your CYA at 40 is fine-- you can take a look at the "best guess chart" link in my sig for chlorine levels that correspond to the CYA levels.

Janet

[Gretchen]

Found the chart and have it bookmarked! We're not losing chlorine at night. I tested night and morning for two days running to make sure. Yesterday was a cloudy cooler day and we only lost less than 2 ppm. We've been losing up to two when it is hot and sunny. I think that's going to be how it rolls this year and I'll keep a close watch. Thanks again!

[CarlD]

This seems to be a high-chlorine year for most people, me included.

I'd start by raising CYA to 50 and see if you do better on chlorine and daytime consumption. You'll probably want to keep your regular chlorine level around 5, not the lower limit of 3.

If pH is stable, don't mess with Total Alk. You have a vinyl pools so TA=170 isn't a problem, if pH is stable.

Carl