Agreed in a home that will be true. Our tanks though are in an outbuilding and we have an outside air exchange device on our heating and a 1/2' tube to our skimmer with fresh air as well.Regarding elevated ph... That will have more to do with being away rather than simply keeping your hand out of the tank. Carbon dioxide in your breath will bring ph down, so it will always trend upwards if the house is empty a while. I even see lower ph on the weekends when everyone is home all day compared to weekdays when everyone is out for 6-8 hours