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The Flying Saucer

Chip Zempel built the Flying Saucer evapotron, and put it to work in the Karma Chickens camp in 2009.  He describes his improvements to the Pumped Cascade design:

"The system is raised so the water can drain through a PVC drainpipe into a 5 gallon bucket, where a 12v bilge pump sends it back up to the top. The first year we tried an evapotron, we had the kiddie pool sitting on the ground. We'd have several gallons of water sitting in the bottom of the pool, but it still wasn't enough for the float switch to switch on and pump the water through the evaporator. When we struck camp, we had a lot of water sitting in the pool!  With the raised system, the pump switches on with less than half a gallon in the bucket. Raising the system on three legs also makes it easy to level the whole thing to get an even flow of water all the way around the mesh cylinder. We simply used door shims under the legs to level it.

"The water from the shower (and other camp water from coolers, dishwashing, etc.) passes through a series of three settling buckets, with finer filters at each stage, so that by the time the water reaches the third bucket, where the pump is, the water is reasonably clean. Lots of playa, of course, but very little food or other particles. We also treated the water with spa chemicals: chlorine to sanitize it and pH adjusters to keep the pH neutral. Any water that did manage to reach the ground through spillage or windspray was pretty clean, sanitary, and neutral. The three buckets were connected to each other by "unbreakable" siphons.

"The Flying Saucer top! In previous years, our evapotron had a plywood top that warped badly, heating in the direct sun, cooling at night, and being constantly wet. When the plywood warped, most of the water ended up running down the mesh in just a couple of places. Last year I hit upon the idea of using a kid's flying saucer sled for the top, but then the question was how to attach it to the mesh. I cut a ring out of plywood, about two and a half inches wide, with an outer diameter about a half an inch larger than the saucer. I attached the plywood ring to the saucer with drywall screws, and then stapled the mesh to the edge of the plywood. It worked like a charm and we had a very even distribution of water all around the circumference of the mesh cylinder for the whole week.

"Another advantage of the flying saucer top was that it helped prevent a lot of problems we had had before with wind. In previous years, with the plywood top, every gust of wind that came along would spray any water standing on the top all over the camp. The dome shape of the inverted flying saucer top really minimized this problem.

"We didn't do any controlled measurements, but I'd estimate that the Flying Saucer Evapotron was easily handling between five and ten gallons a day, and even at that rate the float switch had it shut off much of the time. I was very happy with the way the system worked, and the only changes I plan for this year are (1) to fiddle with the siphons a little to make them more stable, and (2) to take more pictures!"

Chip, in an email reply to a questioner, contrasted his Flying Saucer with the Gray-B-Gon:

“I’m on the road right now, so I can't give you exact dimensions on my flying saucer evapotron. (Besides, it's disassembled in storage.) But I do know the height of the mesh cylinder is 36" which is the height of the roll of 1/4" mesh hardware cloth I bought, and the roll was 10 feet long. So keeping in mind that (pi * diameter = circumference), the diameter of your cylinder (and therefore, of your flying saucer) can't be greater than 38" unless you want to buy a longer piece of hardware cloth. So I would guess my saucer is approximately 36" in diameter. (There's an overlap of a few inches when we wrap the hardware cloth around it.)

“As I explained in [the narrative above], there is a plywood ring that is screwed to the flying saucer which provides a surface for stapling the mesh. The diameter of this ring is about 1/2" larger than the saucer. The water drips off the lip of the saucer onto the plywood and then runs down the mesh.

“I have seen Ember's contraption and been very impressed by it. But I have no idea about how his compares to mine for efficiency. (I'm going to copy him on this email and see if he wants to chime in.) Here are a few thoughts I have:

His relies on wind to operate. If there's no wind, there may be a little bit of capillary action drawing water up the sides, but not much. OTOH, there's almost always wind at BM, and if there isn't, I'll bet people in the camp can be trained to give it a spin whenever they walk by.

“My design, OTOH, needs electricity to operate. So solar panels, a storage battery, a reliable pump. (I've heard stories of people trying to use aquarium pumps, etc., and having them fail in the dust and harsh conditions at BM. It must be a pump designed to handle gunk!)  You say you have solar power, but do some math and make sure you've got enough capacity to actually run the pump for 24 hours a day. (Our first year, with a less efficient design, our pump ran 24 hours a day and my 15W solar panel wasn't able to keep up.) Remember that all those specs -- battery capacity, panel wattage, pump draw -- are for ‘ideal conditions.’ Your solar panel will be covered in dust, your battery will be overheated, and your pump will be pumping sludge!

“Both designs look like they provide several opportunities for Murphy's law to get in there and screw things up. I have a spare bilge pump, and our camp has a lot of reserve battery power, large solar panels, and a backup generator. I would assume that Ember is prepared to deal with broken belts, ripped fabric, clogged bearings, etc. With anything you bring to BM, it's worth it to ask yourself where the weak points are and try to prepare.

“I think in every way, Ember's design looks easier to transport. It looks to me like it may be more fragile than my design, but it's got to be a lot smaller, too. In my design, the kiddie pool is a major pain to transport. It's about five feet in diameter and about a foot deep, and it takes up a LOT of space! In fact, the first two years we used it, our camp didn't have a truck, so at the end of the week, we cut it into pieces and stuffed them into a garbage bag to make it easier to pack out. And then we had to buy a new pool the next year.”