Not a Chemist! Need help with chemicals.

Hello, and welcome to the forum!

Your pH is actually within range (7.0-7.8), but is actually at a perfect level for what you're going to need to do to lower that alk. The TA is actually high--80-100 is more ideal--but whether or not to lower it will depend in part on whether it's causing you any problems, and what the TA of your fill water is. You can lower the TA using the steps outlined here http://www.poolforum.com/pf2/showthread.php?t=191, but if the TA of your fill water is high, then it will be a constant battle to keep it lowered due to refilling from evaporation, splashout, etc. The choice is really yours--but if you decide to lower it, the pH will go down also (see the lowering TA method, and that should explain it all).

If you actually had algae this morning, then you may have vacummed out what you could see, but it's still in the pool. If you had algae growing, you need to shock the pool to kill anything that still may be growing that you can't see. With a CYA of 40, that means raising your chlorine to 15 ppm. Using your 12.5% chlorine, that means a dose of 2 gallons to raise your FC by 15 ppm.

Do yourself a favor and buy a good test kit so that you do not have to rely on the pool store testing and sales tactics. We strongly recommend the K-2006 or K-2006C (same kit, larger reagents in the C version) that you can get from the Amazon link in my sig. Only buy if Amato Industries is the seller, though, because some of the other sellers are substituting a different kit that won't work as well. If Amato is not the seller, wait a day or two to give them time to restock.

Hope this helps!