Thanks Jason, I know about the special test and have one, just wondering what it would do to the FC level, going through a bit of a problem here, was out of town much of this week and the chlorine injection pump stopped working while I was away. Now have a algae bloom and a pool party scheduled for tomorrow, CC of 3.5 last night at 6 pm, added 3 pounds of MPS, at 11 pm I had raised FC to 11.5 after adding 10 gallons of 6% bleach, this morning it is down to 7.5 (CYA much less than 20, was at 25 or so last week), off to buy some dichlor and bleach now.
Ike