AJ I do use the "Pink" antifreeze but I pump it straight out of the bottle through the lines (of course after draining all the water out of the lines and tanks and using the by pass valve on the hot water heater and then draining the heater) But have always been told to not under any circumstance put it in the water tank even tho its not toxic) If you pour it into the water tank it'd take a ton of antifreeze to get it back into the lines and also if you don't by pass the hot water heater then you're talking another 6 or 10 gallons of antifreeze to fill that up.