Test numbers are scary!

cl. - 0
Ph - 7.8
Alk - 200
CYA - 0

25K vinyl IG pool. (3rd year)
I had high CYA last year so we drained about a foot or two of water and refilled several times and used only bleach to chlorinate. Finally got it to a good level of 50 or so. This year we opened to 0 CYA.
Do I need to run the filter for a certain length of time to get accurate readings? I haven't added any shock chemicals yet, but did turn on the tablet feeder. I have some dichlor granuals that I quit using because of the high CYA. Should I put some of that in? It is supposed to raise CYA, right?
Should I worry about the high ALK? I don't know what to do first???

First thing: get some Chlorine in there, you don't want a green pool to fight on top of what else you are going to have to go through.

What seems to have happened is that your CYA was bio-degraded. So, you're going to have to add more so you can retain Cl in the sun. Bad news is that when CYA is biodegraded, the bacteria that do it make lotsa ammonia, which is going to consume phenomenal amounts of Cl to clean it all up. I'd recommend taking the Cl level to 15 and keeping it there until you can hold the same level overnight.


I'd also lower your pH, as using bleach for Cl (I assume this is what you are going to do) will raise it. A quart of muriatic should do it.

I wouldn't worry too much about Alk right now. It's on the high side, but not terrible. I'd be interested in knowing your Ca numbers too, since the two are interrelated.

So your steps are:

1. Cl first
2. Adjust pH
3. Get some CYA in there

Michael

You need to get some chlorine in there or you are going to have a green pool. You can use some dichlor as it will add chlorine and cya at the same time. If you do so, however, it will take some time to build your cya back up and in the meantime, you are going to be losing chlorine fast and have to add it often. Another option is to just go ahead and add some cya directly and then just use bleach. That is what I do. (I also open to no cya each year.) If you decide to do this, add enough per label directions to get to an initial reading of about 30. Add it to the skimmer while the pump is running and then don't retest for it, add more or backwash for about a week to give the cya time to dissolve in your filter. Until you start to see a cya reading, you'll probably need to test your water morning and evening and each time add some bleach. After the cya gets dissolved, you'll be able to just test and dose it with bleach in the evenngs. A good cya reading is anywhere between 30-50, but we usually suggest dosing for the low end. You can always add more later if you decide you need more, but as you have already found out, the only way to lower it is to do a partial drain.

Your alk and ph are both a little high. Take a look at the thread at the following link for information on how to take care of that.

http://www.poolforum.com/pf2/showthread.php?t=191

Hope this helps.

Good advice.

But do not even THINK about T/A now. 200 is the absolute maximum acceptable value in a vinyl pool. Get your pH down to 7.3/7.4 and T/A should come down as well--Michael may be able to calculate that. Any T/A under 180 and over 80 don't even worry about even after everything else is stabilized.

Thanks to all! I added chlorine and will continue to test to see how much more I need. I will have to get to the store to buy stabilizer and I don't think they will be open tomorrow so it will probably be Monday before I can get it. Can I go ahead and add 1 qt. of muriatic acid now to bring down the PH at the same time I'm trying to raise my Chlorine Level? By the way: My Cal. was 120-140 (I wasn't sure which shade of blue to look for?). Is that bad or good?

Actually, in this thread Ben (Pooldoc) advises adjusting the pH to 7.8 so the ammonia products formed by the bacterial degreadation of the CYA will form monochloromines and hitting it with chlorine until the chlorine levels hold.
http://www.poolforum.com/pf2/showthread.php?t=1001

Might be applicable here.
Once the chlorine is holding would seem to be the time to worry about Alk and pH.