Confused about CYA and Chlorine levels.

[tbkp]

I've had my pool for about a year and a half. Haven't had much of a problem with keeping the pool clear. I decided recently to raise my CYA level. I need to get a good test kit. I only have a 4 way and some test strips. The test strips said my stabilizer was low. So I added some CYA. I've been having trouble with algea ever since. Just before I went on vacation ( and about a week after I added the CYA) the pool started turning green. I dumped in 3 gals of 6% bleach in an 18,000 gal pool. The chlorine level on the 4 way test was dark yellow, almost orange/brown. I come back and the pool is green like a pond. No chlorine showed up on the test. I added 3 gals of bleach. 2 days later the pool just as green. Tested a couple times a day. Always very high. Tester goes to 3 ppm. My levels much higher. I added 3 more gals of bleach to kill it off. 3 days later it's getting a little better, but not as fast as I thought.

I've seen a chart here showing stabilizer levels and required chlorine levels. I'm wondering if my chlorine levels are high enough, even though my tester shows off the chart?

[tbkp]

The other thing I might add is that I thought my alkalinity levels were low. So I kept adding baking soda. About 8 pounds over a week. Turns out I was looking at the wrong line on the vial. The alkalinity is about 180. I turned on my pool cooler on. It airs the water out and I'm keeping the PH on the low end.

[tbkp]

To add to the confusion, I pulled out my old test kit. Put in 5 drops and the level was about a 2. The new kit I just bought, may be off. I just added 2 gals of 10% chlorine. Cheaper than bleach at kmart.

[JohnT]

The chlorine and CYA chart is labelled "Ben's Best Guess Chart". Once you have algae, your chlorine will be consumed very quickly. Even going four hours between tests will show a big drop in chlorine. You need to stay after it, going no more than 8 hours between chlorine tests and additions. It will be difficult without a good test kit, but you can use the dilution method to increase your range.

[CarlD]

It's very hard to tell what's going on without good numbers. That's why we always suggest you invest in a good test kit, one that uses the FAS-DPD Chlorine test (not to be confused with the DPD test). You CANNOT rely on strips to give you precise information, particularly on CYA levels.

In lieu of that, you'll need to take a water sample to a pool store and get them to test it and provide us with the following information:
Is your pool vinyl or concrete/plaster?
How many gallons?
Do you use an SWG? (if you don't know, the answer is probably not)
FC (free Chlorine level)
CC (Combined Chloramine level)
pH
T/A (total alkalinity)
CYA (Stabilizer/Cyanuric Acid).
CH (Calcium Hardness)

Since you have a MAJOR Algae bloom you are going to need lots and lots of chlorine to kill it.

Now I suggest you look at PoolForum and see that there are various categories and within them are Stickie'd threads. Read those threads because we've discussed this many, many, MANY times and the advice is pretty much the same.

[tbkp]

Is your pool vinyl or concrete/plaster? Fiberglass
How many gallons? 18,000
Do you use an SWG? Zodiac Clearwater (was in need of cleaning when I got back)

Not real sure of these... Pool test kit are lousy.
FC (free Chlorine level) 2 or 5 depending on which test lit to believe.
CC (Combined Chloramine level)
pH 7.0
T/A (total alkalinity) 170 (test strip)
CYA (Stabilizer/Cyanuric Acid). 125 (test strip)
CH (Calcium Hardness don't know

Pool temp was about 92 when I got back from vacation. I've been running my cooler and now it's about 84. The pool is in much better shape now. I think my new test kit is garbage. I was adding more bleach than ever, by far. The test showed high chlorine. Never had this big of a problem. I thought adding 4 gallons of bleach would last forever. I think I underestimated how fast the bleach would disapear fighting the algea. I've added 5.6 gal 6% bleach and 4 gal 10% chlorine since thursday morning. Wouldn't that be about 60ppm?

[doggie]

You'll never get on top of things until you get a FAS-DPD Chlorine test like Carl suggested. In fact, you need a total test kit for accurate testing of all the things. Throw the test strips away. They are useless, as I've learned by testing them against good test kits.