I'm contemplating an auto topoff for my new 57. The total tank volume is 70 gallons and I think I lose in the neighborhood of a gallon or less a day. I want to include kalk in the system, but I know that that can, on occasion, be dangerous. I'm wondering, if my reservoir were say, 5 gallons, is that enough to nuke a tank if the whole thing ends up in my tank? How about 2.5 gallons?