My main concern with the Sawyer Mini is the lack of an Activated Charcoal filter (an ACF) to go with it, so even if you can filter out harmful bacteria and Protazoa with it, it is not going to improve the taste of the filtered water or remove toxic chemicals or heavy metals. An ACF can do both. I cannot understand why Sawyer do not sell an optional ACF for the sawyer Mini to address these concerns, as they would sell rapidly and make them a lot of money. As they don't offer that option, users have no choice but to try and make their own. One user on youtube made an ACF for his Sawyer mini using PVC tube and epoxy adhesive, but as both of these are potentially toxic I have sought to make one with non toxic materials. My first attempt is made with about 4 inches (100mm) of 7/8"(22mm) diameter clear, but green tinted, flexible Aquarium tubing. Then I cut the threaded ends off two PET drinks bottles, that have a thread that matches the mini's dirty water squeeze bottle...They fit over the tube nicely. They are secured in place with a little clear silicone adhesive. Sawyer sell female to female thread adapters (I have one on order) that will allow me to fit my homebrew ACF between the dirty water bottle and the Mini. A cotton wool ball is pressed into one end of the tube, then activated charcoal granuals are poured into the open end leaving enough space for another cotton wool ball to seal the other end. So not only will this ACF improve the taste of the filtered water but it will also pre-filter the dirty water of most tiny particulates before they get to the Mini (via the cotton wool balls), hopefully reducing the amount of clogging and back-flushing needed. The activated charcoal granuals will only need to be replaced when they stop improving the taste of the filtered water (if Britta water filters are anything to go by, the charcoal granuals should last about a month) and the cotton wool balls can be replaced quickly and easily at any time when they start to look dirty, or they can even be washed and reused in the field if you don't have spares with you. Well, that is the plan anyway...I'm waiting for the Silicone sealant to fully harden, and the Sawyer thread adapter to arrive, before I can finally try it out but I am confident it will work as expected. As for the weight...My ACF on it's own will weigh a little more than the Mini does on its own, as the aquarium tubing has a fairly heavy wall thickness (at least 2mm, perhaps even 2.5mm) and because of the amount of activated charcoal it can hold. For the gram counters among you...My completed empty AC filter body (without the charcoal or cotton balls) weighs in at 27g (0.9oz).