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Old 23-08-2012, 06:35   #1
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Cheap RO Watermaker in Freshwater?

My cruising ground is the Great Lakes, therefore freshwater. I'm wondering why I can't use a cheap ($200) RO system designed for use as a home or aquarium filtration system to produce all but drinking water on my boat. Some advertise that they remove bacteria and viruses. They need at least 40 PSI of water pressure and I would use a washdown pump (45-50psi) to feed it.
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Old 23-08-2012, 09:48   #2
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Re: Cheap RO Watermaker in Freshwater?

It's already freshwater so why not just filter and UV tube it?
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Old 23-08-2012, 09:56   #3
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Re: Cheap RO Watermaker in Freshwater?

If they really require 40 psi... might be hard getting that consistantly... most marine pumps fluctuate wildly... just a thought. I like your idea though...
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Old 23-08-2012, 10:09   #4
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Even easier, just add a bit of bleach to your water tank and then pass it through a carbon filter before drinking it.

The problem with the small $200 RO units ( I have one at home), is that the output is very low and about 75% of the water is rejected. This means that the unit runs for about 30 mins every time you use a liter of water. It would be annoying and use a fair bit of electricity. Installing an accumulator would help, but I still think hearing the wash down pump cycling would get to you.

You also could just install one of the drinking water filters from Seagull IV on your drinking water line if you don't want to add bleach. It should also take out most of the nasty stuff floating around in our Great Lakes.
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Old 23-08-2012, 10:19   #5
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Re: Cheap RO Watermaker in Freshwater?

a Stainless steel UV filter setup is less than $150 for a 3 gal per minute one. I have one in my house. That and a good fine filter might be the ticket.... and take less room. I assume you could run a UV bulb off an inverter?
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Old 23-08-2012, 10:36   #6
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Re: Cheap RO Watermaker in Freshwater?

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I assume you could run a UV bulb off an inverter?
Or straight off of the batteries.

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Old 23-08-2012, 18:34   #7
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Re: Cheap RO Watermaker in Freshwater?

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It's already freshwater so why not just filter and UV tube it?
I hadn't really thought about UV. I'll look into it. Don't know power requirements, and I don't have 110v.
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Old 23-08-2012, 18:39   #8
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Re: Cheap RO Watermaker in Freshwater?

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Even easier, just add a bit of bleach to your water tank and then pass it through a carbon filter before drinking it.

The problem with the small $200 RO units ( I have one at home), is that the output is very low and about 75% of the water is rejected. This means that the unit runs for about 30 mins every time you use a liter of water. It would be annoying and use a fair bit of electricity. Installing an accumulator would help, but I still think hearing the wash down pump cycling would get to you.

You also could just install one of the drinking water filters from Seagull IV on your drinking water line if you don't want to add bleach. It should also take out most of the nasty stuff floating around in our Great Lakes.
My water tank is aluminum. I've heard that it's bad to add bleach to the tank.

I'm concerned about bacteria etc. I'm not sure that filters trap bacteria and viruses. Lake Superior is pretty clean but they do have sewage spills on ocassions. I want to make sure I get ridof bacteria/viruses. The UV idea may be the way.
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Old 23-08-2012, 18:48   #9
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Re: Cheap RO Watermaker in Freshwater?

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Any idea how to employ this bulb in a system. Could you just put the bulb in a PVC pipe and run water thru the pipe?
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Old 23-08-2012, 19:07   #10
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Re: Cheap RO Watermaker in Freshwater?

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a Stainless steel UV filter setup is less than $150 for a 3 gal per minute one. I have one in my house. That and a good fine filter might be the ticket.... and take less room. I assume you could run a UV bulb off an inverter?
Currently, I don't have pressure water. So here's my my latest thoughts.
1. add awashdown pump with 2 outlets, 1 to a pressure tank, 1 to a deck faucet in thechain locker.
2. the pressure tank to a 2 or 3 stage filter.
3. 2 outlets from the filter, 1 to a galley faucet, 1 to the UV setup.

I've looked at some UV filters on ebay. the small ones seem to have 6 to 12 watt bulbs. Not much or a energy burden if you only have to turn them on while drawing water.

Thanks to all of you for your help. It'll be a few months, but if I try this I'll report back.
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Old 23-08-2012, 19:33   #11
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Re: Cheap RO Watermaker in Freshwater?

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My water tank is aluminum. I've heard that it's bad to add bleach to the tank.

I'm concerned about bacteria etc. I'm not sure that filters trap bacteria and viruses. Lake Superior is pretty clean but they do have sewage spills on ocassions. I want to make sure I get ridof bacteria/viruses. The UV idea may be the way.
Yes, depending on the specifics of the alloy, water chemistry, etc bleach can cause problems with aluminum tanks. I've never had problems with aluminum tanks across a couple of different boats, using very mild amounts of bleach, but certainly others who have.

UV tubes will kill all the critters provided you size it properly for the water flow rate. Good pre-filtering is important too so the critters can't hide in the shadow of any particulates.
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Old 24-08-2012, 11:31   #12
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Re: Cheap RO Watermaker in Freshwater?

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Any idea how to employ this bulb in a system. Could you just put the bulb in a PVC pipe and run water thru the pipe?
Sure, get some glass tube, strap the bulbs to the outside, cover with a piece of pipe to keep the UV contained and away you go....a UV treatment system on the cheap!!

12.7mm (1/2 in) O.D. Corning Pyrex Glass Tubing - Wale Apparatus
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Old 24-08-2012, 11:49   #13
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Re: Cheap RO Watermaker in Freshwater?

Why do you need a watermaker...or even a filter for lake water? You are almost always a short sail from a source of potable water. Wouldn't tankage for, say, five days be more than sufficient?
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Old 24-08-2012, 17:42   #14
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Re: Cheap RO Watermaker in Freshwater?

Not sure what turning on/off a UV bulb would do to it's life. A small Stainless Steel unit complete is really pretty cheap for what you get. The bulb has to be in a glass tube sealed from the water. You could batch it I suppose....: turn the bulb on, pump thru the UV into a day tank....
here's a typical small unit: http://www.freshwatersystems.com/c-4...v-systems.aspx
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Old 27-08-2012, 21:40   #15
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Re: Cheap RO Watermaker in Freshwater?

I think I have a 12Volt UV light and filter set up in the shop that has never been used. If you're interested I'll find it and give you the specs.
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