Tim problem is the depth of the cut needs to be just right, and those microfilter casings are made of tough plastic.

I don't know I guess I'm afraid I might slip doing it by hand.

The first time i read a report about trimming off the excess on hammock forums the guy used a dremel. That's a hand tool but a fast blade is also easier to control. I guess a lttle reticence about which way to proceed is why I haven't trimmed the thing yet.

Any good ideas about trimming the casing on a microfilter out there?

I just received the 4 liter dry-bag from Mountainfitter. The black bag! Appears very well made and wicked light at .5 ounce. Just about a perfect size and shape for a filter/hydration bag.

if I can trim the micro-filter to Bill F's weight of 1.9 oz that would yield a sub 3 oz gravity filter with a 200 gallon life that is easily modified on the fly for hydration and is minally prone to clogging. Dry-Bags with a semi-rigid rim are really easy to fill as well.

I'll up-date when I get to it. ( don't hold your breath! )

Thanks to Mary to pointing me to this thread. I just went to REI and grabbed the "Platypus Gravity Works" replacement filter. It's an uberlight little cartridge that, I believe, is intended to go inside the gray, bulky filter portion of the dual platy system. I also bought a platypus connector and hose.

My question is this, can I replace the in-line, seychelles filter on my ULA with this little guy and expect it to work as well as what is currently there? If so, I think I can deal with the "weight" of the silnylon and will have a perfect system so long as platy hoses mate with my ula bag/fittings.

Here's a pic:

I believe that filter only takes out the bad taste, you might check to see if it filters out the bad stuff like Giardia.

From REI's website:

"•Removes flavors, odors and many organic compounds from filtered water to improve the taste
•The Platypus GravityWorks Carbon element should be used to improve the taste of safe water sources only; element does not remove viruses, bacteria or protozoa from water"

This is a routine aspect of my day job (cleaning up toxic waste sites) and a carbon filter WILL remove gasoline, benzene, chlorine, and many pesticides.

It WILL NOT remove pathological organisms and the "plate counts" of bacteria will typical go UP after a carbon filter because of the tremendous surface area they give the biofilm to live on and because it dechlorinates the water passing through it.

It will improve the flavor and decolorize many waters. It may make it chemically safer. It will not protect you against biological issues. Pity, because it is small and compact!

It weighs so little I may just add it in line with the Seychelles for added/pre-filtration.

This is what I use now. Maybe David could chime in on this one.

Jack

David, you said "This is a routine aspect of my day job (cleaning up toxic waste sites) and a carbon filter WILL remove gasoline, benzene, chlorine, and many pesticides."

Does Carbon remove any metal/mineral contamination from mine runoff?

I have always heard that nothing will remove mine runoff contamination which is actually one of the primary issues in many Colorado and locations in the Western US in general.

The CR-100 claims effectiveness against micro-organisms although their website leaves me unclear whether it is the sintered carbon or some separate filter that blocks the passage of small particulars. The company is well known, the claims reasonable, and I would be fine relying on it for taste and biological treatment.

Combined with aqua Mira in more queationable areas, this may do the trick. A+ discovery wasabi for was that Platypus hosing fit the ULA reservoir.

The sawyer 3 in 1 filter is designed to go in the hydration bladder hose and normal suction on the bite valve will fill your mouth coickly. Unlike the platapous carbon filter it will filters out everything but viruses. All you have to do is stop fill your bladder, repack the bladder into your pack and go. The Sawyer 3 in 1 weighs 3 ounces.

Hi everyone, I'm looking for some knowledge and or help.
I used some leftover silnylon seconds to make a water bag for a gravity filter, and almost immediately after filling with water it begins to "weep" out of the fabric. I understand it is only water resistant and not water proof but I was wondering if this is common and just due to the weight of the water pushing out or did I get a bad run of silnylon?

Most silnylon isn't waterproof

"Shield" from thru-hiker.com is better

You could put silicone diluted with mineral spirits 10:1 and it would make it pretty waterproof, but then it would probably contaminate your water

I wonder if fabric in general is safe for water? Not designed for that. Any fabric might contaminate your water.

Maybe better to use water bag.

This is the direction I'll go, at least it will be an easy switch over. Thanks for the speedy reply.

Thanks Steven. I just ordered the Sawyer three way filter. It's time to replace the ULA/Seychelles filter - its heavy and has done its job long enough. I didn't like the squeeze system's looks. I know many do fine with it. This will definitely be a safer bet than the platypus carbon filter. Sawyer lists the weight @ 1.8 oz. well see about that. My ULA bag is silnylon and has never had a weeping problem. I still want to try and make a cuben replacement. But don't have the tools to add the trim and grommets needed for the drawstring. I think it would get pricey too. Will probably just keep the ULA until someone produces a cuben option or offers to build me one for cash or trade.

Edited by bcutlerj on 07/28/2012 15:28:39 MDT.

Randy:

Carbon as a slight affinity for metals, but not much. I've looked mostly at Arsenic (flavor of the local water and something I encounter in various spots in the Far- and Mountain-west USA) and carbon does reduce it a bit, but the % removal is small even in large-capacity carbon vessels (one-day residence time) that I use for work.

For metals, typically we use an ion-exchange resin. It is highly effective, and occurs quickly, but I'm not aware of a small-scale version. If one posed as an engineer doing a feasibility study and talked Westates or Calgon or some other vendor out of a pound or two, you'd be set for life but often they want you to send them many liters of the water and they conduct a bench-scale test to generate design specs.

Other options for metals are distillation and reverse osmosis. Either of which you might do for drinking water at home or cruising on a sailboat but never while backpacking.

I'd note though, that a microgram of infectious stuff breeds in your body and can make you quite sick from one exposure. While cancinogens and toxics are dose-related - more exposure is worse, less exposure is less risk. If you live in Fallon Nevade - TREAT YOUR WATER FOR ARSENIC!!!, but if you are just passing through, you'll have 1/365 x 1/70 the risk of a life-long resident.

UL for metals (and sorry, this is a campsite technique, not while hiking): a pinch of baking soda to raise the pH (acidified water dissolves MUCH more metal) and a pinch of alum (which can be bought cheaply in small quantity in very well-stocked bulk food / spice departments of health food stores). The alum allows all sorts of stuff to flouculate (clump together) and sink or rise in a water. The alum is edible - it is used in some cooking. It is amazing to compare side-by-side Colorado River water with and without alum for settling times - there's an easy 10-fold difference AND the alum-treated water is MUCH clearer of silt, metals, etc. Then skim the scum off the top and decant the clear liquid without disturbing the sediments on the bottom. Biological matter will also have tended to sink or rise, so the clear liquid will have a MUCH lower biological load, but while this would greatly reduce your bio exposure, it shouldn't be considered 99.99% effective like a good filter would be. (Your filter, will however, go MUCH longer between cleanings if you settle out the crud first).

Dave,

Could you tell us more about alum? There seem to be many alums. Which one do you recommend? How long does the process take (like 50% is 5 minutes, 80% in 20 minutes...) How much alum per liter? Alum seems like a good solution for me, since I use a siphon from a 3 liter water bag. Thank you.

TZ

This recent thread and my own curiosity prompted me to revive this older thread:

http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=67849

I'm curious to know whether anyone's tried using a ceramic element in a gravity flow system. I'm looking for something that's not necessarily UL, but low maintenance, will filter 5 months of water for 4 cyclists, and will take a beating.
I've considered MSR autoflow systems but the number of filters we'd go through deters me from that option. I'm also reticent to pick up a carbon filter for the same reasons.

Any thoughts?

Thanks,
Matthew

The life of any water filter is somewhat dependent on the initial clarity of the water and whether you use a prefilter (to catch the big stuff).

I've seen a new ceramic filter rendered almost useless within two quarts of water, simply because the water was grimy and there was no effective prefilter. If you know what you are doing, you will learn the quick filter cleaning method for yours.

--B.G.--