Most efficient gravity filter system – need market update

Ike, I saw that website also. Looks like it is selling the good stuff, all right. I hope it works. I pulled the trigger today and bought the Katadyn carbon filter, and the last replacement charcoal they had (basegear.com). When it arrives, I'll post my guess as to the ASTM particle size of their charcoal. I'm just guessing here, but I would think that the smaller grain would (1) offer more surface area per volume, and (2) slow down the flow of the water through the carbon (which might give it more time to work). Anyway, please keep us informed as to how it goes for you, and I'll do the same. Now, where am I going to find some murky water to test?

It turns out the yellow fuel filter thats i dissassembled has a 10-20 micron capability. Meaning powdered carbons should work with it, losing only a small percentage of the carbon through use.

>>Now, where am I going to find some murky water to test?

Cherry Creek Reservoir

If anyone is interested, i found a sample page where they offer small portions for testing at $5 for a few oz.

http://www.buyactivatedcharcoal.com/product/SAM

I will be testing 2 powders(hardwood (highest surface area/iodine number) and coconut) and 2 granules.

I don't know much about water testing.

What I would do is to contact my local water supply officials and ask them how they test the local water supply.

If they have a thousand-dollar test, you can ignore that. They might have some simple test too.

–B.G.–

In the past, I've had wells tested and they just tested for the presence of e. coli and of nitrates (from fertilizer). I know that municipal systems now test for the presence of other chemicals, too. I agree that the local municipal water folks may be your best source. Some states provide free testing for well water.

You would need to test samples of both the filtered water and the unfiltered water to be sure the absence of e. coli/chemicals/whatever else they're testing is due to the filter and not a clean water source! I really wonder how many of the filter companies have actually done this!

This has been a most instructive discussion!

Also, you have to test the water filter device to make sure that it has not become contaminated.

Once I furnished a First Need filter on a group backpack trip, and I caught one inexperienced person putting the clean end into the raw water and vice versa. The whole thing had to be boiled and chlorinated to make sure that it was clean afterward.

–B.G.–

FWIW… I am doing the AT in March and was thinking of using gravity vs my MSR hand pump. If I go gravity… I would like carbon filters to help with taste.

Please let us know when you have data!

Ike, just received the Katadyn carbon filter with the activated charcoal. They use extremely small-size carbon grains–probably in the range of 30-40 ASTM sieve size. Much smaller grains than the ones you are thinking of buying. The cartridge holds about 25 grams of the carbon.

I ran a couple liters though it last night, without using chlorine tabs. I just wanted to wet and rinse the carbon first, and then I ran out of time to do any more testing. The tiny particles certainly offer tremendous surface area, but it seemed to slow down the filtration rate considerably. The dry cartridge with carbon weighed 2.5 oz, and when wet, it weighed 3.2 oz. It is extremely slow to dry out (I opened it and let it sit in the dish rack to air-dry overnight–no weight difference 8 hours later).

I just wanted to tell you about the Katadyn grain size, before you made your purchase. I'm thinking that the larger grain size would only work if you had a much larger filter housing. It's probably used for things like swimming pools and large aquariums. Just guessing here. If you go ahead and buy some larger stuff, please let us know how it works for you. I hope I am wrong in thinking that it won't work with the small volume of that filter housing.

>Ok so all my parts came in. I made the filter setup. First you have the dirty platy bag, then you have the ON/OFF stopcock(which is lighter than the one you push to close by a few g). Next is the sawyer with quick disconnects and finally the carbon filter and the clean bag.

Here is the homemade filter. Now i used a unique process to keep the carbon from working its way outward. I cut a small circle of micron fabric that would fit inside the prefilter(about a quarter), then i pulled the layers apart because it was too thick to allow me to screw the filter back on. (the biodiesel micron filter material has a felty layer and a smooth layer, i pulled the felty layer off). So now the charcoal cannot work its way back up and get in my filter.

I used the blue bite valve from my platypus hosing and a platypus push-pull cap that i modified to fit the platy setup. Note that the black rubbery small piece from frontier pros will also work, but is bulky. I pulled off the push pull section of the cap, cut out the 3 pronged inside so it was hollow. Then i put the blue bite valve piece over it, ran the hosing through it, and gorilla glued both parts. I wanted straight downward pressure, an elbow would lesson the pressure. The parts are picture below. You can use either the tiny blue bite valve piece, the frontier pro bite valve, or make your own:

Here is the various carbons i order. the granular one has grains that are as big as tiny tiny tiny pebbles.(sorry cant think of anything that size), the powders are so fine, like a dust, if you blew on it, you would have a massive mess:

Bulk 1-Micron biodiesel material from Ebay:

Homemade pre-filter. The water runs through it like its not even there, it does little to impede the flow:

Im still waiting for the cuben so this will have to do for now. Will test the charcoal tommorow.

I also need to come up with another way to encorporate the micron filter without using so much material. The material pre-water was 1oz, now the little bag above weights 2.6 oz. WIll have to work on this.
Setup including prefilter is 11oz. This is the sawyer purifier, subtract a few oz for the filter version.

I will be testing the tractor filter seen here as well as another homemade one made out of a small bottle that i have not made yet. Will make tonight. I anticipate the cuben setup will shave off an oz or so.

Is the katadyn refillable? I estimate my filter holds about 5g of carbon. I think i may have to go with the homemade energy drink bottle filter as it will probably be more in the range of 15-20g. Since this is high quality carbon, i think i should be able to get away with less.

Ike,

The Katadyn is refillable – not sure how much it holds though… I haven't weighed it empty/full. Setup looks pretty cool.

The carbon for the Katadyn weighs about 25 grams. (28 grams for the full foil packet.)

These type of connectors weigh less than a gram, whereas the quick A disconnects are around 6. These are just as easy to disconnect as well.
A black one came with the sawyer purifier.

http://www.usplastic.com/catalog/item.aspx?itemid=29899&catid=603&clickid=searchresults

I tested the small yellow/clear filter and the water was slightly cleaner than when it entered the filter, but it was not in contact time enough to truly be cleaned by the carbon. I tested the other one as well, same result. So when i went home i made the following device, i have not tested it yet, but i truly believe this one will work beautifully:

I made it out of a small coghlans bottle that i got out of ordering their small travel bottle kit here:

http://www.trekitoutdoors.com/xcart/Contain-Alls.html

I also used a 5 Hour energy bottle:
http://3.bp.blogspot.com/_qsDpLDiIGuk/THyBMIX4BII/AAAAAAAAByg/00sRLk1t9v0/s1600/hourenergy.jpg

I also used these quick disconnects from USplastic.com:
http://www.usplastic.com/catalog/item.aspx?itemid=23016&catid=743&clickid=searchresults

==============================================

I cut the bottom out of both bottles, and they slipped right over each other snugly:

Next i cut small holes by twisting a razorblade down into the top of the caps of each bottle. I inserted the small quick disconnect into each hole and super glued it(i tried using pvc cement, may try again):

I then cut small circles out of the 1-micron bio diesel bag and put it inside the cap of each bottle to stop the charcoal from escaping into the filter or the clean bag:

It held about 35g of carbon, but i cut the bottles shorter until the bottle held about 25g-28g(same as the katadyn).

I then wrapped Duct tape around the outside edge of the outside bottle to secure it in place. Using two clear bottles would be really cool since you could see your charcoal.

I think this system is going to work great, cant wait to test it tomorrow. It weights 1.7oz with activated carbon. The best part about this, assuming it works, is that it will be refillable cheaply, and in the field if necessary.

Brillant!

Nice job seeing what was possible, where I only saw bottles.

Thanks.

I tested the system at home, but had problems with my sawyer purifier. I pre-primed it earlier today but it seems not to work now. Will preprime again with stronger water flow and see if thats what it needs.

I tried it with the charcoal bottle filter. The water taste great, definately worked. My tap water tastes terrible but now its fine-even good i would say. However, im having leaks around where the 1/4" quick disconnects connect into the bottle cap. If someone knows a strong adhesive that would work in this situation, i could use it. I tried superglue but its not so super, i have PVC cement but im worried about applying it accurately to such a small area. Im also concerned about using such a toxic chemical. Any help would be appreciated.

Ike, you are making great progress. Thanks for sharing your concepts. As for using Super Glue or other cements, I'm nervous about possible toxic leaching (Super Glue releases a small amount of cyanide when in contact with water, for example). Could you just use 2" pieces of tubing to slide over the Coghlan's cap tips with good friction, and then use your quick connects to connect that 2" tube to your longer tubing? If the Coghlan's tips have a smaller outside diameter than the inside diameter of your tubing, you could do a "splice" approach, having the right size tubing to shove onto the Coghlan's tips, and then another, larger ID tube to insert those into. I'm finding that it doesn't take much friction to hold a Silt Stopper or Katadyn filter in line without it popping off. In fact the 1/2" ID tubing will act as its own quick connect, where you can easily shove it on/pull it off the inlet/outlet stems of the SS or Katadyn filter. Eventually, the tubing will likely be stretched enough such that it doesn't hold a frictional grip, at which point you simply replace the 2" piece with another (carry a couple extra in your kit).

Ike,

I'm in no-way knocking your MYOG 2-bottle container (clever!) but what about a MSR/Sweetwater Silt Stopper as a carbon container? I don't have one, but I'm thinking that if the filter element is removed, you are left with a plastic container that already has the correct-sized in/out ports and a double o-ring seal that screws open. You could cover the ports with circular discs of the 1-micron bio diesel material like you did with the bottles.

This might be a little cleaner and without the need for the glue or duct tape. Maybe someone who already has a silt stopper could comment on whether this would work. I might pick one up this week as I also have a new Sawyer in-line filter to work with for next season.

The sweetwater is ceramic not AC. The filtering element looks much heavier than the myog one ,seeing as its a much larger higher density plastic piece. Its also non-refillable, once the element is gone its gone. One of my goals was to have a serviceable cheaply refillable system. It will work fine though for a long time since you can scrub the inside. If you do it, post for us.

The powdered activated carbon was too fine for the filter. It clogged the 1-micron material and slowed the water flow significantly. While it better AC, it wont work for DIY unless someone can find a material that it wont clog but will allow flow. Stick with the granules.

Ike,
Steve was suggesting the SiltStopper part of the Sweetwater as an AC unit.

I have done this. It holds about 5 grams of AC with the fiber filter in place, not worth much filtering, IMHO.

But is 5 grams of AC enough to have an effect? AC requires a certain amount of contact time to work properly. Im pretty sure that 5g wont do it. The katadyns have around 25, if they could get away with 5 they would. Most small elements have more than 25. At such low exposure times you would almost certainly want a powder since it will have the strongest filtering power. I can think of no way to make a powder work without it getting into everything else.

"All activated carbon forms including granulated activated carbon (GAC) have a tremendous surface area resulting from its porous structure. GAC filters degree of effectiveness depends on the flow rate of the water and contact time with the water. "

BTW the ductape works great for holding the ends together. Its already carried anyway so no penalty there. I am considering silicone to be used around the connectors . Effectively sealing them in place and preventing leaks.

I tried using the Silt Stopper, with the filter element in place. I filled it up with large granules of AC. It didn't do anything for the taste. I think more AC, and finer grains, is required.

The GAC-1230C sample that you see on the previous page has grains about the size of medium sized particles from a pepper shaker that you twist to break up the pepper. Seems to be ideal size.