Steve, As you realize some DI bottle suppliers would like to make their money supplying more DI bed bottles and some want to make it with carbon bottles. If I was in that business, I would certainly know where my biggest profit comes from. The best approach is to research it yourself. Often nearby academic facilities can aid in this endeavor, of course, they want money too, but their information does not have a profit motive. City water departments have all of the information you need, but you probably need a great deal of push and maybe influence to get it. I am not familiar with the water in Sunnyvale or in Tulsa; however, I know of several users in San Jose/Santa Clara area that use in sequence (1) carbon filter, (2) descaler, (3) reverse osmosis, (4) anion bed, (5) cation bed, (6) mixed bed. This gives them 10--18 megohm water (a point for argument) that they feel is required for their process. These come from at least 2 equipment/bottle suppliers, maybe 3 different suppliers. I assume the setup is based on recommendations of these several suppliers for the water in that area and not just one with a profit motive. Phil Hinton ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################