Quote Originally Posted by jnorris
Here's my latest test:
FC 2.0 ( I know, it's low!)
TC 2.0
PH 8.0 (was 8.2, added dry acid, but apparently didn't add enough)
TA 110
CYA 40
Don't know about calcium level.

This is a new vinyl pool, just filled 4 weeks ago. Haven't shocked yet. Pool builder gave me a BIG TUB of cal-hypo (consolation prize for the pool leaking half the water out in the first week!), it is 68% strength.

I am going to get muriatic acid tonight. I have a little mustard algae. I am using the trichlor sticks right now. Will probably stop that in a week or so, but I will use those when I go out of town (which is alot). I don't have anyone who can add pool chemicals for me while I'm gone, so I will use the sticks for that, but am planning to switch to bleach soon. I just thought I'd use the cal-hypo to shock since I have it. I know it can make the water cloudy if my calcium is too high, but I don't have a test for it. I guess I could have it tested at a pool store. But I thought I'd go ahead and shock it once with the cal-hypo and see what it did. I just really don't want to be buying 8 or 10 3 qt bleach bottles at a time to shock if I don't have to.

So, my original question, how do I know how many of those scoops that are in the tub I use? Like I said, it looks like it would hold about 8 ounces of liquid, but I know that doesn't measure weight, and when the package says to add a certain number of ounces, it probably means by weight, doesn't it?

Thanks,
Judy
First off. Stop using the tri-chlor sticks. Your CYA is 40, and if you use them while out of town it will go up. That's ok if you have room, and you do, but if you use them when you aren't going away, the CYA will STILL go up.

FC is a little low--CYA=40 means you should never let FC go below 3ppm and shock by going to 15ppm.

More importantly you MUST get your pH down. With a pH of 8, a CYA of 40 and an FC of 2, you have the equivalent of NO chlorine in your pool. As pH goes down, chlorine effectiveness goes up. So you need to add muriatic acid to get it down to 7.3-7.8--but aim for 7.4-7.6.

68% cal-hypo is the good stuff. If your CH level is nice and low, feel free to use it to chlorinate instead of the sticks. Vinyl pools can tolerate calcium levels from 0 to 500ppm.

So: Get the pH down, use the Cal-Hypo to get the FC up, and stop using Tri-Chlor sticks, saving them for when you travel.