Some corrections!It is probably best to mix three bags at a time. Any more is hard to handle. The mixer you need is a six inch "Jiffler" not a "Jiffy". The Kremer lime putty has no trace of magnesium, the current price is about $5 (U.S.) per lb. Lime prices are rising right now because of the drastic rise in natural gas prices. If you decided to rent a big mixer, check back with me as to more detailed instructions.