theres a recent thread about it...i think its called alk/cal. There's a big discussion about how PH readings are affected, giving false PH readings..or was it alk?? Anyway which test kit are u using? Try a different brand of it and if the calcium reading comes out the same then maybe try the kalk/vinegar solution...IMO i never had much success personally with vinegar...the livestock didnt look good after dosing it.