Tuesday, February 28, 2012

Ceramic filtration

After a couple of false starts, Steve on s/v Siempre Sabado has a working 5-micron water filtration system aboard.

As I was walking back to Siempre Sabado yesterday afternoon, it seemed to me that she looked like she was listing a bit to port. Down below, a glance at the inclinometer confirmed that we were indeed leaning to the left. Not a lot, but some.

Since we haven't changed what's on board, haven't added or subtracted fuel, etc., this can only mean one thing: the water tank is getting low. I had been kind of hoping this wouldn't happen until Lulu returned because she's bringing me some plumbing to make the filter installation neat and tidy. But, she won't be back until Sunday so I decided to bite the bullet and jury-rig the filter setup so I could fill the tank with filtered water.

As I explained in an earlier post, mounting a ceramic filter at the point of use didn't work very well since the foot pump just didn't have the oomph to suck the water through the 0.9 micron pores in the filter element. Pushing the water through the filter with the foot pump was even less satisfactory. However, I also knew that I didn't really want to run every drop of water from the dock hose through the ceramic filter to fill my tank with ultra-filtered water because, if the dock water had any suspended solids in it, it would take forever to fill the tank because the ceramic filter would plug up so quickly. You might remember that I went through a similar experience with fuel filters.

So, here's what I ended up doing...

All the water going to the tank is first run through a Rotoplas 1 paper filter. In the earlier post I referred to this as a 5 micron filter. It isn't. It's a 50 micron filter which is still pretty freaking small. I connected this in series with my new TurMix ceramic filter. The Turmix doesn't have nearly as much information on the ceramic element as the other ceramic filter I bought, but I'm assuming (hoping) that it is as good or better. One thing it has that the other unit didn't is an active silver element in the center for control of pathogenic bacteria. Nice touch.

Here's what the system looks like:

Notice the belt and suspenders approach here? The little squirt bottle is BacDyn, a local product with an active ingredient of colloidal silver for disinfection. We give the tank fill tube a few squirts of this prior to filling. Then, from the right: white supply hose carrying dock water; black Rotoplas filter housing containing 50 micron element for removing most of the suspended solids from the water; bright and shiny TurMix ceramic filter with silver element for removal of very small particles as well as most bacteria; and then the clear hose into the tank.

From the tank, we draw water through another Rotoplas filter housing. The difference is that this one uses an activated charcoal element with yet again, more colloidal silver and, presumably, a finer micron count than the 50 micron filter.

This water goes from the tank, through the filter, through the foot pump and out the faucet. This secondary filter is just protecting us from anything that might have already been in the tank before we started filtering our incoming water.

I just checked my stash and I see that we have tons of the 5 and 10 micron filter elements I bought in the US for the unit that filters our watermaker's backwash water and they will fit the Rotoplas housings quite nicely. It should be a few years before we have to buy any new filter elements.

This is what the new filters looked like before I started running water through them today

And here's what they looked like after filtering roughly 50-60 gallons (a scientific wild-ass guess) of water:
You can see that the primary filter doesn't show much of anything but the ceramic is coated all around with a light coating of brown stuff. This stuff washed off easily with just a wet dishrag. For the record, it took me 3X as long to fill the tank with filtered water as it did with unfiltered but, fortunately, I didn't have to stop partway through to clean the filter to restore flow.

So that's our filtration system. When we're making water with the watermaker, the only filter that will matter is the final one. But, I'll let you know in a few months how everything is panning out after we have a little experience under our belts.

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