Questions re Geo Method

Thanks to all for the info. Yes, I was thinking the stuff the Calgon guy used to bring to resupply - wrong! I'm going to make a trip to K-Mart in a few days to see what they have to offer. Our Walmart SuperCenter is on my "__" list more often than not and all they offered was a little 24oz bottle of liquid for just under $6. The Borax is lots easier to find and may give that a go. Apparently doesn't matter if I use powdered or liquid laundry detergent. I'll also take another look on Amazon or ebay. In addition to finding something that does a good job, I'm all for making it economical. I loved the Odorlos, which CW started carrying again a couple of years ago, but has now vanished from the shelves and also the catalog, as I remember. Hate it when they do that! Who would think so much time would be spend thinking/shopping/assembling something for the black tank, but it's am important part of Rocky and surely don't want anything to go wrong. I like the pre-mix baggie idea. Easy. Thanks again for all the input.