Hi Tom,
500 ppm is considered the upper limit, anything below that is acceptable for drinking water. However once the membranes get to the point of delivering either 500ppm of close to it they are arriving at replacement time. 280 is acceptable and of course at start up you will see higher levels. My duo 60 has manual controls and I run product water to waste for a couple of minutes after start up. So long as the tds goes down to an acceptable quite quickly dilution would deal with it. 0.75l/m is not far off 60 l/h the and if you give the watermaker some long use you may find you get it up there. So in summary. 500ppm is the upper limit but you wont die if it is a little higher. Anything in the mid 300 and below is quite acceptable. Once my tds gets over 400ppm on a regular basis I start planning for replacement. Like anything, the best treatment is regular use.
Regards
Danny
SM 299
Ocean Pearl

On 24 July 2019 at 05:05 Thomas Peacock <peacock8491@...> wrote:

I’m hoping to get a few tips on our water maker. We have a LaRochelle installed Dessalator, I believe a D60, SM 240, 24 volts only. We have used it only sporadically.

I put new membranes in 2 years ago. I am trying to be sure it works properly, we are in the Chesapeake Bay, which is only brackish water so we don’t use it there. Going to Martinique this fall.

The Dessalator manual at one point says we should have 250 TDS, at another it says 500, which certainly tastes brackish.

At 40 bar we get 270, at 60 bar about 330, which then goes down to 280 after about 5 minutes. We get 0.75 liters/minute.

Is this acceptable performance? I am more concerned about the TDS than the rate. I would like to clean the membranes as suggested by Dessalator, all they say is “cleaning solution”. Is this the same as the pickling compound, sodium metabisulfite?

Thanks as always for everyone’s insights.

Tom Peacock

SM 240 Aletes

Chesapeake Bay