Additives for Grey Water Holding Tank

We use the Camco because it is available at Wal Mart and elsewhere. It is lemon scented for the gray tank. The other one is thick and deep blue and I don't care for it's odor but we never smell it in the tank. We've used others that work about as well. Gray water can smell up the place,if you rinse grease and meat scraps, and other things down the sink. We are careful to only let trace amounts of grease ever find it's way into the gray tank and no meat scraps etc. The gray water most often smells like shower gel or laundry detergent. With the lemon stuff, on drain and flushing the tanks leaves the hose smelling like lemon, unless used dandruff shampoo or something but it eliminates and chance of dandruff in the hose. :)