Can't keep chlorine levels up

[PoolDoc]

readings from this morning (shocked with 2 gallons of 10% LQ at dusk the night before).
FC -1.38
TC- 1.65

Pool volume of 17,500 => PF:7

2 gallons of 10% *should* have raised your FC by 12 ppm. There are 3 possibilities: your 10% bleach is actually 2 - 4% (common when bleach is stored at high temps) OR you've got something (like agae as mentioned) creating a high chlorine demand, or you are getting bogus ColorQ readings (it *is* a 'guess-strip' reader!)

Buy 18 gallons of PLAIN 6% store brand bleach from a store with high volume sales (=fresh bleach), like Walmart. Add 6 gallons EACH evening after you get the bleach, and test FC in the AM. You *should* be seeing levels of 20+ ppm in the AM. Also get a cheap OTO drops kit: at 20 ppm, OTO is very dark yellow with an orange tinge. The 2nd evening, brush the heck out of your pool. Also, add the bleach VIA the skimmer, after making sure ALL chemicals, tablets, pills, feeders, etc in the skimmer or pipeline, are removed. Adding the bleach that way will help clean your filter.

By the way, you can test the ColorQ by collecting a sample, and then testing that sample every 20 minutes for an hour. The variations between the results is reflects the minimum (not: maximum) testing error you should assume in every ColorQ result.

[CarlD]

You mentioned using algaecide. What algaecide, namely, what is in it? Are you still using it or did you stop? Algaecides can cause more trouble than they cure. Even Polyquat, the only type we recommend, can cause your FC to drop (I count on it when I'm closing my pool).

I'm not suggesting that stopping using algaecide will stop your problems, but it will reduce them.

[cbednara]

or you are getting bogus ColorQ readings (it *is* a 'guess-strip' ).

Is the lamotte colorq not reputable? Here is a link to what I have. http://www.lamotte.com/component/opt.../mid,/page,19/

I wanted a test kit that used drops of reagent. Reviews were good for what I read and I liked the photometer giving me readings rather than myself eyeballing the color match.

[PoolDoc]

My bad -- I was thinking of the AquaCheck strip reader. The Lamotte ColorQ is

- 3x as expensive as the K2006
+ possibly more accurate than the K2006 on pH and CYA
- probably less accurate on TA and CH
- less accurate on chlorine at low levels
- much less accurate than the K2006 at high levels (> 7 ppm)

I've asked Waterbear (who's been out with surgery) to take a look when he gets a chance. He's played with more test kits than I have. By the way, the K2006 does a titration (color change, not color match) for chlorine, TA, & CH.