conversion with bleach begun 4/5/11

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I'd try the sun first before anything else. The MPS will only confuse the issue in the short-run since it actually registers as CC unless you get a special test interference remover. I think the sun will likely help. Just keep the FC levels up as you've been doing. Has the filter been backwashed/cleaned since the pool has become clear? Does the pool smell like chloramines (i.e. "bad pool smell")?
 
backwashed, a bit cloudy, but not bad. In the pacific NW we are not apt to see much sun until late June. They are predicting several sunny days beginning tomorrow.
If I don't see a drop in cc over the weekend I will need some idea of what to do next with the mps or something else.
 
While you are waiting for the sun, why don't you try a bucket test so that we can see if something will work before subjecting your entire pool to it. Find a large bucket that is thoroughly cleaned (soap and water, then multiple rinses), then fill with pool water, then after letting it sit for an hour or so test the water to make sure you are still registering CC in it. Then add a small amount of MPS, just 1/8th of a teaspoon in 2 gallons or scale up if your bucket is larger. Mix and wait 24 hours. Measure CC again. If it's low, great, but if it's higher than before, then that's the MPS interfering with the CC test. A dosage of 1/8th teaspoon in 2 gallons is roughly equivalent to 21 ppm FC in oxidizing power, but it's a different kind of oxidizer that is selective in ways that are somewhat different than chlorine.

You can repeat this experiment with sodium percarbonate though I'm not sure where you can get a small quantity of it. It's in products such as ProTeam® System Support. You can get a 2 pound jar of it at The Chemistry Store as well as larger quantities. Now for this test, you'll need to add a larger amount because it has to dechlorinate what you've already got in the pool (it produces hydrogen peroxide in the water and that reacts with chlorine to get rid of it). Probably adding 1/4 teaspoon would do the trick. You'd measure the CC before doing the treatment and then again 24 hours later after the treatment. However, you would then add chlorine again (1/2 teaspoon of 6% bleach to 2 gallons) to the bucket and see if the CC re-emerges 24 hours later but be sure you measure FC as well which should be roughly in the 10-20 ppm range (it won't be 20 ppm because some will get rid of hydrogen peroxide leftover in the water). If you don't measure any FC, add more chlorine until you do.
 
It's officially been a month and our cc's are at 1. I hope it will drop more today and tomorrow and we can get on with things. We had one sunny day, then our gloomy rain came back. Not a stellar spring here. We have opted to open the pool despite the rain.

I have a CYA question: I tested it and it seems to have dropped from 30 to 15 or so (i can barely see the dot when it is full; if i didn't know there was a dot i might miss it).

Should I add more CYA now or wait for the cc to drop to .5 or less first?

How often should you test your CYA?

Thanks.
 
Normally you only need to test CYA two or three times a season. It does tend to drop slowly over the course of the season due to splash out and backwashing (if you backwash). Also, the CYA test isn't all that precise, +-15 or so.

It would be fine to raise CYA a bit at this point.
 

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