No, not surprising at all. 4 bags of Cal-Hypo in 7000 gallons is going to significantly raise your FC. Those are 1 pound packages of 75% Cal-Hypo, it would have initially given you about 50ppm FC before the algae fight started consuming it.
Being Cal-Hypo it did not raise CYA but it did raise CH.
Your PH test won't be accurate with the FC at 19
Please test and post the results like this
FC
CC
PH
TA
CH
CYA
Being Cal-Hypo it did not raise CYA but it did raise CH.
Your PH test won't be accurate with the FC at 19
Please test and post the results like this
FC
CC
PH
TA
CH
CYA