Re: [Amel] Re: 60 l/hr dessalator

Chris Smither <yachtakwaaba@...>

Hi Kent,
   We have an 80/L hr seafresh on our Santorin, and have had for 17 years. I changed membranes about 3 years ago.
   I regularly inhibit, (some people call it "pickle") the watermaker with Sodium metabisulphate - this is sometimes called "camden tablets" and is used by winemakers.
   I keep a 25L white plastic plastic water barrel, with tap and hoses cut to length, on the boat and use that exclusively for pickling the unit. 250gms of bisulphate in the barrel is just the right concentration for short  term out of use (up to 6 months).
  The advantage of the white plastic is that - if your marina water has chlorine in it you fill the barrel and leave it in the sun for 24 hrs, and that destroys the chlorine.
   The Bisulphate can be left in the 50 and 5 micron filters and keeps them clean as well - it's a win/win technique.
   You just have to remember to run the first 30/40L to "dump" on recommisioning.
    I also have an operational rule - I only use the watermaker in deep clear sea water - that prolongs the life of the filters and the membranes.

Akwaaba SN 027

PS I forgot - pay attention to the temperature pressure graph in the watermaker instructions - most are set up to operate in N Atlantic water temperatures - at 800+ psi.
Warmer water needs a lower pressure - here in the Indian Ocean/Andaman Sea a pressure of 600psi gives full flow. The sure way to shorten membrane life is to "over drive" them.

--- On Fri, 3/11/11, john martin <symoondog@...> wrote:

From: john martin <symoondog@...>
Subject: RE: [Amel] Re: 60 l/hr dessalator
To: amelyachtowners@...
Date: Friday, March 11, 2011, 2:06 PM

Hi Kent,

We had a similar problem with the salinity sensor built into the water maker, it stopped sensing that the water wasn't good enough quality.  We now have a TDS Meter (Total Dissolved Solids Meter) onboard.  It is a small battery powered water tester that reads up to 1000 parts per million (ppm).   We bought the unit after talking to Mark at Great Water in Maine, who has sold us our membranes (but he doesn't sell TDS meters).  Mark is very knowledgeable and offered this advice:

"When your water maker membranes are new, they will produce water at 100-200 ppm. 500 ppm is generally when the water will start to taste salty, and some yachties tolerate up to 700 ppm to extend the life of their membranes."

Although it is possible to have a complete sudden failure of the membranes, most of the time it will be a slow deteriation of the menbranes and give you ample notice, hense we are happy using the hand held TDS meter.

We purchased the TDS meter, made by Hanna Instruments, on ebay from National Industrial Supply in CA for about $15 (they only sell on ebay).  It comes in handy for testing the tap water when at a marina as well. We tested the water here in Venezuela and found it to be cleaner than bottled water, but the people don't drink it.  We do. 

We also have a chlorine tester on board (the optical type), to test local water for chlorine content, because lots of countries do not use chlorine in their water, thus you can use that chlorine-free water for cleaning your membranes.

SM 248

To: amelyachtowners@...
From: karkauai@...
Date: Thu, 10 Mar 2011 17:19:37 -0800
Subject: [Amel] Re: 60 l/hr dessalator


Hi, Gary,
Thank you, thank you, thank you.  That really helps.

Does anyone know if there have been similar issues with the older 60 l/hr units like mine, or was this an issue only with the 160 l/hr units?

While I am stuck here at the dock, I will find a watermaker supply and see about installing a charcoal filter, an in line sensor (if the test you suggest shows that the sensor in my unit isn't doing anything) and clean with metabisulfite.  If I find that my salinity sensor isn't shutting off the flow to the tanks I will talk to you about installing a cutoff switch to the solenoid. 

Again, thank you for taking the time to lead me along by the hand, Gary.  I love you folks on this forum.
Steady as she goes,

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