This is one of those posts that I think,
I wade through a lot of chaff, but sooner or later, I come to the
wheat. Thanks to Rick for putting it up.

Brian Whatcott Altus OK

On Sat, 26 Nov 2005 07:40:04 -0600, Rick Morel
wrote:

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It's not done that way. The 30 micron goes BEFORE the 5 micron.
Believe me, both filters will need regular cleaning. For the "believe
me part" - I used a watermaker with my own silty water kit (more
later) every day, with occasional breaks while in marinas, for 2
years. Made water in clean ocean, fairly clean bay, dirty bay and even
filthy canal. And no to some of the have-to-UV-or-sterilize folks. The
watermaker water went straight into the water tank, then into us with
absolutely nothing done to it. We're still here and healthy.

Now, here's the "later" from our old web pages.....

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A watermaker is W*O*N*D*E*R*F*U*L if you plan to spend a lot of time
away from "civilization". We do, so our watermaker is way up there on
our list of glad-we-gots. Our Pur 40E is the only one I have
experience with, so don't know if it's the best or not. I do know it's
worked fine running 4 or 5 hours per day for about a year. The only
time it's touched is to put a bit of silicon grease on the shaft every
now and then, and cleaning the prefilters. "They" say these things
have to be run a bit daily (or be pickled) for trouble free operation.
Must be true. Others we've talked to that run them rarely and/or have
one so large that they run them say a half hour every other day
complain.

However.... The watermaker was the only thing that required some
"adjustments" before we were totally satisfied. Here's the basic
story.

Our new watermaker came with a 30-micron prefilter and instructions to
use only in "clean sea water". There is a "silty water kit" that is
overpriced, even by marine standards. It consists of another
prefilter, with a 5-micron element, and a small centrifugal pump The
pump is to make up for the reduced flow through the extra filter. Now
one can make water anyplace except where there's oil or chlorine in
the water. The latter is pretty rare in bays and canals! So is the
former for that matter, especially when the water intake is about 2 ft
underwater.

An Omni under sink or similar filter and 5-micron elements from a
place like Walmart, and a small centrifugal faucet pump from a marine
or RV place is much less than half the price.

WARNING! Do not use paper filter elements! Use only poly. Paper can
break up and get into the membrane.

It all worked, but there were problems with cavitation in the
filters, causing POPS! of air going though the membrane. Water
production seemed fine, but we opened the air bleed on the watermaker
pretty often. Taking a break here, PUR seems to say air in the thing
cuts down on production and is undesirable, but does no harm. Those
marine chain store advisors say air explodes though the membrane and
will damage it. In either case we need a good flow of water though the
system.

Without going though all the fiddling with it all, the final solution
was to feed the system from our sal****er pump and add an accumulator.
The pump is a regular Shur-Flo pressure water pump; the accumulator
keeps it from short cycling and assures there's always a pressure feed
to the prefilters.

Simply, here's the setup for trouble free freshwater from pretty much
anything you're floating in, in order of connection.

Thruhull
Strainer
Pressure water pump (1.8 gpm or so Shur-Flo)
2-gal accumulator tank
30-Micron prefilter
5-Micron prefilter
Watermaker

The prefilters are after the pump for two reasons. We use the
sal****er pump for other things so the prefilters would need cleaning
much more often, and they're really made to work under pressure, not
vacuum.

Without the accumulator, the sal****er pump would constantly cycle
every few seconds. Not good for the pump, aggravating to the ear,
extra current draw and the watermaker will "suck down" water pressure
to below zero. With the 2-gal accumulator, our pump cycles on for
about 21 seconds after about 2-1/2 minutes off. Water pressure never
drops below 10-psi. I'm sure the regular 1 or 2 qt accumulator would
work fine; the pump would just cycle more often.


Ramblings and Opinions
Here's the standard disclaimer. This is stuff I've learned from
researching and personal experience. It works, so I'm right. I'm sure
there are many other "rights" to choose from.

Size your watermaker so it'll run several hours a day, and run it
every day. It's going to cost X Amp Hours per gallon of water,
regardless of how many gallons per hour. Do follow the manual and run
though enough product water to fill the prefilters and membrane each
shutdown, about 3-qts in our case. This keeps the creepy-crawlies from
growing in there. Also keeps the smell of said creepy-crawlies away.
PEEEEEUUUUUUU!!!!!

Put your raw water instake as deep as possible to get away from
floating crud, including oil. I tee'd into the engine intake. Get the
extra 5-micron filter. It just doesn't make sense to cut out 95% of
the places you could make water. Okay, why 95%? I don't know. Sounds
good. Thing is, how much of the time is one in "clean sea water"?
Hardly ever is probably the answer for most of us.

I hear about "pickling" the thing as if it were some dark ages
torture. You just put a couple caps of powder into a couple quarts of
water and let the watermaker suck it through. Of course pickling is a
good argument for running every day. It should be pickled if not used
for more than 3 days in warm water, a week in cold.

I was concerned about replacement prefilter elements, and their cost.
No need. They can be cleaned over and over and over. The criteria is
they're okay as long as they're still firm and not collapsing. I
changed ours after a year - just seemed the thing to do even though
they were still firm and looked good after many cleanings.

Sal****er pressure pump and accumulator is better'n sliced bread!
Assured good water flow, plus longer time between prefilter cleaning.

Rick