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Old 07-07-2012, 04:55   #1
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Watermaker pre-filtration and sea water "quality"

I'm in my first season with a watermaker onboard and am trying to fine tune my usage and expectations. I'd welcome advice from experienced users to speed me through this process.

The machine is a Spectra Catalina with their automatic control. Filtration consists of, in order:

1) Integrated seacock/strainer

2) Spectra-supplied strainer. I don't know the filtering size, but I'd guess it's 50 micron or so.

3) Spectra supplied boost pump.

4) Spectra-supplied 5 micron paper filter.

The problem I've encountered is that my paper filter gets plugged up very quickly. I know this is due to operation in less clear water, and I can point to one or two spots where I normaly would not have run the machine. Once I was in a salt water river, but I was doing the initial commissioning of the system and needed to test it out. That time I kind of expected to sacrifice a filter to the cause. The filter lasted for several hours of testing, and then a few more hours out in open water (Massachusetts Bay) before plugging up. I probably got 5 hours out of it in total, and wasn't really surprised because of the river operation.

The second filter was run across Block Island Sound and down Long Island Sound, and again I only got about 5 hours out of it.

All of this leads me to a few questions:

1) How do you visually judge the water clarity to decide whether to operate or not? I thought I was doing that, but apparently not very well.

2) Who else runs a watermaker in the northeast, and where do you run it and where do you shut it off? This might help me adjust my expectations and operation.

3) For the more technically inclined, should I add another pre-filter with courser (and hopefully less expensive) filters ahead of the 5 micron filter that is currently doing all the work?

Thanks in advance
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Old 07-07-2012, 05:24   #2
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Re: Watermaker pre-filtration and sea water "quality"

We run a 20 micron Watts 9.75 x 4 inch pleated PF followed by a 5 micron pleated PF. Regardless, we plug up fairly quickly in harbor areas, in the ICW, etc. Using the system (25gpm) in the Bahamas, the filters lasted substantially longer. It is practical to reverse flush the filters, though you need to avoid introducing chlorine from your (dock-filled) freshwater tank. We flushed with our saltwater deck-wash hose. Best way to cut cost is to buy in quantity on the net.
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Old 07-07-2012, 05:37   #3
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I can't help much with the waters in the NE US, but in the Carib we get lots of hours on the 5 micron filters, more than 100 hours on a Spectra Cape Horn Extreme. I really just change it about every 2 months for good measure. Production for us varies more based on voltage than anything else.

Except....and this won't be your problem the unit is too new. But keep an eye on the mesh strainer. It will eventually plug up. I initially treated it like an engine strainer and pulled out all the big stuff and rinsed it off. Looked good on the outside. That's not enough though, the inside gets plugged with small marine growth that has to be cleaned out more thoroughly.

How much stuff is in the filter? Ours is usually just a little gray when we pull it out.
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Old 07-07-2012, 05:47   #4
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Re: Watermaker pre-filtration and sea water "quality"

We have a 20 micron prefilter followed by a 5...probably change out the 20 twice as often as the 5, never run the unit in marinas. If there for a short time, just flush it with fresh water every 2 days for about 2 minutes, o'wise pickle it and wait 'til we leave before rinsing it out and start it up again, have a carbon filter on the fresh water outlet from the tank for fresh water flushing just in case, but avoid putting dockside chlorinated waterin the fresh tank anyway.We haven't taken on dockside water for 3 years (that's when we installed the watermaker).We change the 20 micron filter about every 3 months in the south pacific....
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Old 07-07-2012, 06:30   #5
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Re: Watermaker pre-filtration and sea water "quality"

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Originally Posted by chrisjs View Post
We run a 20 micron Watts 9.75 x 4 inch pleated PF followed by a 5 micron pleated PF. Regardless, we plug up fairly quickly in harbor areas, in the ICW, etc. Using the system (25gpm) in the Bahamas, the filters lasted substantially longer. It is practical to reverse flush the filters, though you need to avoid introducing chlorine from your (dock-filled) freshwater tank. We flushed with our saltwater deck-wash hose. Best way to cut cost is to buy in quantity on the net.
How quick is quick in a harbor areas or the ICW? 5hrs of operation? 10?, 20? maybe more? I've been avoiding harbors and have not run in one other than the initial commissioning which was an exceptional situation. I did run it through the Cape Cod Canal because I forgot to shut it off, but otherwise I've been in open water a couple of miles or more from shore, and the water appears clear in my wake.

When we pull the filters they are visibly skanked up, so at the moment I think they really are plugged up as opposed to having some other intake restriction.

Anyone operating in New England waters? That would be the best reference point for what to expect.
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Old 07-07-2012, 07:04   #6
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Re: Watermaker pre-filtration and sea water "quality"

We also have an older model Spectra and I agree with the others, you need a 20u filter...
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Old 07-07-2012, 07:07   #7
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Re: Watermaker pre-filtration and sea water "quality"

We have an older model Spectra and I would agree with the others that you need a 20u filter...we have also cruised the NE and never had any problems...
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Old 07-07-2012, 07:49   #8
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Re: Watermaker pre-filtration and sea water "quality"

I try not to use dirty water. Only make water when well off shore or when the vis is about 12 feet. I have had filters last 6month or more using these rules.
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Old 07-07-2012, 08:33   #9
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Re: Watermaker pre-filtration and sea water "quality"

"1) How do you visually judge the water clarity to decide whether to operate or not?"
Tree, if you really want to get objective about that, you use a secchi disk, which is easily and cheaply home made.

Secchi disk - Wikipedia, the free encyclopedia

Lower the disk into the water, pay out the line until you can't tell the black from white, now you've got a visibility measurement. In the NE US, the waters are fairly rich with organic matter so the visibility is generally low, often under six feet as compared to a hundred+ in tropical waters. So yes, your filters will clog much more quickly, but then again, the NE US usually offers excellent potable water at little or no cost, versus tropical prices.

You can always plumb in more filters. Perhaps home water filters would be effective enough to take out a lot of the material, you might ask some of the suppliers about micron sizing and then try a cheap internet supplier for them. (Hardware store prices can be 5x higher than web prices.)
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Old 07-07-2012, 12:36   #10
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Re: Watermaker pre-filtration and sea water "quality"

OK, I know a couple of things about Spectra watermakers.
I'm assuming this is a new Catalina MKII 300 MPC 5000. These units only come with a five micron filter. Adding a 20 micron filter before the five will do little and may not help you at all. Secondly, your Catalinas MPC control board is set to measure the differences of the input and output sides of it's filtering system. Adding a second 20 micron filter can easily throw these parameters out of wack and the MPC will go into a very early service pre-filter alarm. Certainly operating the watermaker in less than ideal water condtions is going to clog your pre-filter sooner than later. This just means the filter is doing it's job. It's not unusual in the NE Bay waters, inlets, and ICW to quickly clog pre-filters even when the water seems somewhat clear to your eye. But there can also be several reasons if your system is going into a service pre-filter alarm other than just a clogged filter. Many issues I see with water makers are more install related than they are equipment issues. Who installed it? Also the parameters on the control board may need to be checked to makes sure the pressure sensors settings are correct. But if the water is too dirty, it's too dirty. Ideally watermakers are meant to operated in the clean open waters. Near shore operation as in Bays etc. is usually going to give you problems. If the NE waterways is going to be your area of normal operation a good set of spare five micron filters is a good idea.
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Old 07-07-2012, 14:40   #11
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Re: Watermaker pre-filtration and sea water "quality"

When we put on our first and only water maker years ago the dealer told us and I quote "if the water aint blue dont use it !!" it's always worked for us and our pre filters lasted for mos at a time !! just our 2 cents
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Old 07-07-2012, 14:49   #12
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Re: Watermaker pre-filtration and sea water "quality"

Call stectra. I have talked to spectra owners and they would replace the filters with new and then clean the old. They would reuse them. and would have one clean and ready one in clean water and one dring and would just cycle them around
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Old 07-07-2012, 16:33   #13
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Re: Watermaker pre-filtration and sea water "quality"

Why wouldn't a 20 in line first not help?

My 20 plugged up first every time.

That is how my (ex) system was set up.

In Florida though.
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Old 07-07-2012, 20:05   #14
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Re: Watermaker pre-filtration and sea water "quality"

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Why wouldn't a 20 in line first not help?

My 20 plugged up first every time.

That is how my (ex) system was set up.

In Florida though.
Because yours was a 150 with a lot less flow than a Catalina 300. The 20 will clog up a bit faster, but if you only used a 5 micron in yours (you wouldn't do this because your control was set up a bit different and the pressure sensor design is different) you wouldn't see a big enough difference in how much sooner it would clog up to be worth the effort to add one if it wasn't already there. The higher pressure, flow and boost pump on a Catalina 300 creates a whole different situation. The Catalina 300 is designed to produce a certain amount of product given the design parameters intended. These smaller sized units are built for energy efficiency based partly on the flow. Much older Spectras had three pre-filters, a 50, 20 and 5 Micron. A lot has been learned since then and the design changed to fit the newer systems. The key is as bobconnie points out, watermakers should be run in clean water. If a watermaker is to be cosistantly used in areas that are questionable then a media filter system is a better option, but good ones can get expensive to set up and won't warrant the small savings of a few extra spare filters. Guys, these are Spectras, not some off the shelf pressure cleaner pump units. They are expensive, giving advice on these based on one or two units you've owned in the past is not always a good idea. I can't begin to tell you how many of my calls are from Spectra owners who have a better idea. People can take my free advice here, or I'll be glad to give them my phone number to set up a service call.
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Old 07-07-2012, 20:21   #15
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Re: Watermaker pre-filtration and sea water "quality"

The boat came from the factory (Grand Banks) prepped for a watermaker, and I did the install on the Catalina. And yes, it's a MkII 300 MPC 5000.

I'm happy to answer any questions about the install. I think I did it all correctly according to the docs from Spectra, but welcome any thoughts on improvement. Here's the basic setup:

- Groco BVS750 3/4" combination thruhull, valve, strainer.
- Forward scoop on the thruhull
- About 2' of 3/4" hose to the Spectra-provided strainer
- Spectra strainer is direct mounted to the service valve/boost pump
- All strainers and the boost pump are below the water line
- Boost pump to the 5u filter is about 3-4' of hose.
- From the 5u filter onward it's all factory plumbing.
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