wondering if anyone out there is using a gravity filter system, and if so what are you using. i was thinking about using the seychelle filter with a couple of platypus bags. anyone out there using somthing different i would love to get input from others about their system. thanks
will

Hey Will,

Yes I use a homemade version based on Ray Jardine's design and think the world of it. Really easy to fill and fast to filter (about 1L/min) and resonably lightweight (6.2oz when dry). Very easy to make.

Some people have posted positive things about the H2O Amigo and Seychelle filter, but I am not a fan of either one.

Another good option is Aqua Mira though, I gave it up after using it for a week straight due to wait times and taste.

I used a Seychelle inline filter as part of my hydration system for a few hundred trail miles (over perhaps five trips totaling three weeks). I used it inline straight from a dromedary and in a gravity setup. At first, it was OK, but grew slower and slower to the point that it is essentially worthless now. At it's best, it would filter 4 liters of water in a few hours (I always used it overnight, so can't say for sure). However, that performance didn't last for long, despite vigorous cleaning and careful source selection.

I have since switched to Clearwater and Aqua Mira. Used at lower concentrations, I don't mind the taste too much, and the dependability is unbeatable...

I use the H2O Amigo from ULA. Love it! Works great, it's fast, no maintenance, has a pre-filter. Weights 9.6 oz for complete kit.

I'm using the ULA h20 Amigo, albeit modified depending on my needs. I replaced the stock drawcord water bag with an ultralight 4 liter waterproof drysack. This way, I can hang the bag in camp and have extra water, and also wash my hands without fear of spilling any water. The stock drawcord bag, which doesn't seal close at the the top, would sometimes shift postion and leak or spill water out.

I also can use a General Ecology First Need replacement canister instead of the stock inline filter. The GE canister, as per the manufacture's specs, can be used in gravity filter mode sans pump. This canister is the only mechanical "purifier", not filter, that is EPA rated to remove viruses, protozoa, and bacteria without the use of iodine or other chemicals.

The canister is slighty heavier than the ULA supplied one, but I feel a little bit safer that no matter what water I might encounter, it will be 100% potable.

I've used the Amigo and loved it, switched to chems for the lightness and like them, but now I purchased a 2 oz inline filter from justdrink.com. I put the filter inline in my platy hydration tube.

Viola!

Not only does it do great job as an inline filter, but slide off the removable platy bite valve and you convert it instantly to a gravity filter with a better flow rate than the amigo.

I normally just carry the platy during the day and a Liter of gatorade, then filter another 2+L plus refilling the platy for dinner and breakfast.

Fill up the Platy in the morning and you're off down the trail in just a minute.

0.7 oz for the 1L platy, 2 oz for the filter, 4 oz for the hydration setup, and 1.4 oz for the 2+ L platy ... 8.1 oz for the whole setup vs 7 oz for just the Amigo and no extra baggage in your pack

Mark,
My home-made Gravity Water Filter only weighs 5.61 ounces. Add the Platy 1 liter at (your weight) of 0.7 ounces and my set-up only weighs a total of 6.31.

I first started out with a stock Amigo filter but dumped the filter that came with it for the much better Katadyn Hiker Pro Microfilter. Next came a new bag made from Cuben Fiber and a lightened filter, etc, etc and soon it was a completely new set-up. There is a thread in the MYOG Forum showing how I did it.

I used the seychelle in a gravity filter set-up for some time. I used a big zip platy on top with a platy resevoir underneath. I set it up so that while hiking the filter outlet was attached to hose/bit valve. Then when at camp I pulled the hose/bite valve off the outlet and attached a short hose and resevoir.

I prefer the Aqua Mira currently. Gravity filters have the advantage of reducing your chemical exposure, just be sure to understand the filter's capabilities or lack there of. The seychelle filter usually left me with runny/loose stools due to inadequate filtration ~:(

"The seychelle filter usually left me with runny/loose stools due to inadequate filtration ~:("

has anyone else experienced this problem. my issue is i am prepairing for a thru-hike of the pct and i am worried about chemical exposure for such a long time. i really am not sure what my solution could be. i had planned on using two bladders and a seychelle in between but "runny/loose stool" is not going to cut it for me. i would rather use chemicals. there is a new in line filter i saw recently called the sawyer in line filter available at rei. has anyone experienced that or heard anything. i have always hated regular filters because they weigh so much and take forever to pump. i thought the gravity filter would be a good solution, becuase it would reduce weight and i could do other things wile it was filtering, but it sounds like it might not be the safest solution. any thoughts.
will

Seychelle is, in reality, a cyst filter. I can think of a few reasons why one may have problems using it.

1. The filter is cracked and so is ineffective.

2. Bacterial diarrhea (bacteria are generally too small to be filtered by the Seychelle based upon the Mfr's statement of its absolute pore size; bacteria, from more than one taxonomic family, can cause issues in the human's hintermost parts)

3. Sometimes Crypto can fold over on itself (while not the most common shape for Crypto, i've seen this myself under a microscope) and in this shape may(???) be able to pass through the Seychelle pores.


IMHO, Giardia should NOT be able to make it through an undamaged, properly functioning Seychelle.


You might consider trying the SteriPen UV-C water purifier coupled with a pre-filter (as simple as a bandana over the mouth of your 1L container). Mine takes 4xAA batts (not sure about what batts the newest smaller model takes). I know, I know - batteries; not the ideal solution. You might query the Forum users who have hiked the PCT about the availability of AA batts vs. CR123 batts (used by the AquaStar UV-C purifier) for resupply.

Edited by pj on 10/29/2006 01:34:24 MDT.

I use a gravity filter most of the time, with Aqua Mira or Klear Water as backup or extra precaution if I really want to make sure I get the best drinking water I can.

I started using a platypus combination where I have the 4 liter water tank (big zip and handles on top, tube hole on bottom), the filter link attachment to a 3” piece of hose then to a 5 micron Sweetwater filter (used as pre-filter) to a 3’ piece of hose to the 2 micron Seychelle filter and a final short piece of hose. Everything rolled up in the water tank and weighs just over 10 ounces. Since then I purchased the H2O Amigo and use that as my primary gravity filter.

Being only 5’6” I do need to tie it off on a higher branch, but I’m okay with that. If I feel the need for extra precaution, I can always add the chemical treatment after the water has been filtered.

Edited by mikes on 10/29/2006 08:38:01 MST.

nick- you said you were using te general ecology canister in a gravity setup. how well is that working for you. what is the flow rate. how heavy is the canister. i cannot find any information on the net about flow rate or weight of the canister alone.
will

I was inspired by Bill F's filter mods and so purchased a Hiker Pro filter and started cutting. Instead of a bag I used platapus 2L bag with a shower kit attached. I mated the outflow nipple from the filter to the shower intake hose. Remembering what a friend told me he had done, I used my silnylon bucket and put a hose outlet on it. On the oppisite end of the hose I placed a cheep, generic, plastic fuel filter. I gather water in my bucket. I don't have to be very careful anymore about floaties and silt because I filter those out before the water ever touches my bio filter. I've used it for three weeks and have no visible soil on the Hiker Pro. When the pre filter gets slow I just flip it around on the tubing and backflush it and I'm good to go. Eventually it will clog but then I'm only out $2.50 for a new one verses the cost of the Hiker. So far it has worked well for me. I could try and post some pics if you are interested.

Brian
T-BACK

yeah i would definately be interested in photos
i am still trying to figure out what setup i want. i am starting to consider one of those uv lights.

Here are a couple of pics from my last AT hike. Hope they help.

The canister (just weighed it again) is 11.7 ounces saturated. I can fill up a liter bladder in about two to three minutes. With the tubing and the ultralight drysack, the total comes in to about 13.5 ounces.

The General Ecology website:
Particle Retention (microns)
.1 nominal
.4 absolute

It's not the most ultra-light. It is the lighest, most reliable, and absolute safest "purifier" setup I can think of right now. There are lighter "filters", but they won't protect you against bacteria and viruses.

I've researched chemical tablets, and they depend too much on water temperature and wait times.

The Katadyn Micropur MP1 Purification Tablets specify a fifteen minute wait to kill bacteria and viruses, and up to a four hour contact time to kill Cyryptosporidum. But, that is at a water temp of 4 degree Celcius, or 39.2 degrees Fahrenheit. I can't find any fact sheet or manual (every other product/filter has a PDF) on their website concerning these tablets. What if the water you encounter is much colder?

I guess one can use the stock seychelle to remove cysts, and then the Katadyn tablets to remove bateria and viruses.

I almost forgot to add that --concerning the custom setup I have-- one can increase the flow rate by rolling and squeezing the closed drysack water bag, like a tube of toothpaste, if you will.I thought of this one day when I realized that I always squeeze liter bags of I.V. saline to incerase the flow rate to patients who are in severe stages of decompensated shock.

Edited by nyc_paramedic on 11/07/2006 16:08:11 MST.

Just an FYI.

There are many sub-micron filters available that will eliminate bacteria.

And, much to my surprise and initial extreme skepticism, one filter (from Sawyer) claims to eliminate non-filtrable (as they were always previously known) viruses, measuring tens of nanometers in size. As Gomer Pyle, USMC, used to say, "Surprise! Surprise! Surprise!".

pj,

Have you used the Sawyer? I've been intrigued by the description, but wondering how much suction/pressure is required to get water to flow through such a fine filtration. I'd emailed them, but never got a reply (though it may have been filtered out by the spam filter at work, where I emailed from).

dk

Deborah,

No, i haven't used the Sawyer yet. It's on my "soon-to-be-acquired" list though.

As far as suction, they say that is NOT an issue due to the surface area involved. I guess i'll find out for myself next late winter or early spring when i acquire one.

Sorry i couldn't be more help.

Thanks, pj (also for your answer on the Epic on another thread).

I think the Sawyer filter is probably in my future somewhere. I like Brian's setup for gravity filtration also (substituting the Sawyer?), though I'm not sure what type of hose fitting he got on the silnylon bag, or how it's attached. It looks from the picture to be smaller than a garden hose fitting.