Re: Sterilize the watermaker

Gary Silver

Hi all:

In my early years of ownership of Liahona (Amel SM #335, purchased new July 2001), I would faithfully pickle the membranes with Sodium Metabisulfite (SMB).  Since I was working back then I would often have the membranes pickled for 6 months at a time.  Within a few years I had the bobbin that interconnects the two membranes and the shaft of the low pressure feed pump fail from corrosion.  I discovered that SMB is a acid when mixed with water, see . After that I developed my own automatic timer to flush my membranes with product water when the boat is un-attended (pictured here,,timer,20,1,0,0 ).  I used a 24 volt fish feeding timer wired to a 24 volt relay and tied into the pressurized water system wiring of Liahona.  When I leave the boat, I set the timer to run for 2 minutes every other day, actuate the flush valve at the low pressure pump, and as the pressurized water pump starts to run in it's automatic mode I switch the timer on, thereupon the relay goes to it non-actualized state (open) and the pressure pump power is cut. When the timer commands it, the relay closes and supplies power to the pressurized water pump to flush the membranes for the two minutes.  I measured the amount of water used and in two minutes with the flush valve set to flush, about 4 liters of water goes thru the membranes.  My membranes have been in tip top condition every since, I haven't had to fiddle with pickling solution and I have never replaced another component for corrosion. This along with the continuous salinity measuring system with 110 decibel alert and manual "save vs discard" function have been the best modifications I have made to the Dessalator 160l/min water maker aboard Liahona.  It is a shame Dessalator didn't include these features as standard equipment.  I think I paid $20 US for the timer, $10, for the relay, and a couple of hours time to fabricate and install.  The continuous salinity measurement system was a couple of hundred $US.  I have promised for some time to draw up schematics and parts lists for these projects and now, having retired, perhaps I will do that in the next few days.  Will announce when I post them. 

In the meantime, I recommend you have your boat caretaker manually flush your membranes with product water (water from your Amel tanks) at least once a week and avoid the pickling process.


Gary S. Silver, M.D.
s/v Liahona   
Amel SM 2000 # 335
Puerto Del Rey Marina - On the hard for the hurricane season

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