Thanks Watermom!

Yes I did mean CYA! I know the trichlor tabs have stabilizer, but I was just going by the best advice I was getting at the time (knowing in the back of my head this probably wasn't correct). I have now upon reading your response removed all extra tabs & turned off my tab dispenser.

I just tested the water myself using my K-2005 test kit. My chlorine is now very high, but prob as a result of the shock (Zappit does not have any stabilizer, that much I did confirm). My levels were above what the test would allow, so per the kit's instructions I used the dilution method and used 1.8ml of pool water filling the remainder of the 9ml sample with my house drinking water (we have a filtration system that is supposed to remove most of the contaminants and chlorine). I read the result to be about 1.5ppm which I am supposed to multiply by 5 giving me FC of 7.5.

I also used my test kit to check the CYA levels and I think I read it to be about 100 ppm

I have read the "Best Guess Chlorine Chart" page. I have some concerns about running high levels of chlorine to compensate for the high CYA levels b/c I have three young kids of which one has skin sensitivity issues. We also regularly have friends over who also have little ones and I guess I would feel like I had to issue a disclaimer before we invited anyone to swim. Am I over reacting?

In a best case world, wouldn't it be better to lower the CYA and run Chlorine at 1-3ppm?

Is there any way to lower CYA other than draining the pool? I called my pool company yesterday and they passed me on to a service company. After a brief conversation with this professional, he mentioned that rather than draining the pool I could have used a CYA reducer, but I didn't inquire further b/c I assumed my initial draining of 4 inches would have been enough. When I asked about this product this morning at the pool store, they said there wasn't such a thing.

Our pool is 16,250 gallons, plaster, attached spa, runs 10 hours per day with a variable speed pump at 2500 rpm. We also have an Ozone system attached to the pool (I honestly am not sure what this does for us, all I can remember is that is is supposed to help us use our chlorine more efficiently). I hope this is the type of info you need!

Thanks so much, I am so ready to start enjoying our pool again!