Spectra oddity

[akopac]

So I have an awesome spectra 200 watermaker that is older than creation, and has given me amazing service over the years. Since changing the membrane out about a year ago it will give ppm readings of just over 300 after I change prefilters, and each day after I have changed out the pre filters the ppm goes lower (like down 20ppm per day) and lower until I swap out the pre filters again and it will go back up into the low 300ppm’s again. Any thoughts?

[markxengineerin]

Are you watching/recording the pressures on the inlet feed to the clark pump, or the exit pressures? As I understand it, higher pressures = lower PPM. Some info here:
https://www.cruisersforum.com/forums...pm-256126.html

Not sure how to explain what this has to do with your pre-filters, but at least if pressure is changing (or water temperature), it's a clue.

[senormechanico]

PPM is not PSI.

[markxengineerin]

I don't think anyone said PPM is PSI (?)

[akopac]

Just the input pressure and it’s good with similar pressure and flow every day. I was thinking there might be a leaky seal in the membrane housing or something. Maybe the membrane has a problem…