[Mike55]

For those using HF5 Membranes, what psi are you running yours at and what is your in/ out tds reading are you getting?

I've just replaced my old one and am getting seriously below the output tds I was expecting and produced from my previous membrane so would be interested to see how others are getting on.  FYI I have an in tds of 280, a psi of 50 and the lowest out tds I can get is tds 032.

Cheers, Mike

[Ian Lancaster]

Hi Mike,  there's something wrong there!!  The membrane is  removing about 88.5% of dissolved solids, it should be at least 95% (tds 14).  I had one once where the sealing ring round the end of the membrane had folded back on itself as I inserted it into the housing so some raw water was escaping past it and mixing with the product water at the other end.  I took it out again and gave it a good smear of vaseline then watched carefully as I put it back in.  Another possibility is you need more pressure - the manufacturer's definition of 'Ultra Low Pressure' and yours are not the same thing!!

Something else to remember: the important pressure reading is that at the membrane, not what pressure comes out of the mains.  If there was no waste outlet then all the mains pressure would be applied to the membrane, but as you open the waste valve so the pressure at the membrane drops.  The more you open it, the lower the membrane pressure so to achieve a decent pressure at the membrane you need a booster pump.

[Spruce]

HF5 membrane. 4 years old. Water pressure 50 psi. Tap tds fluctuates between 90 and 120. Today its 98. Reject water from r/o is 2ppm. That's 98% efficient.

I've never seen the r/o producing more than 2 since it was new.

I have no booster pump. The usual ratio of pure to waste is 1 : 1.  At this pressure the r/o is producing 2 lpm minute of pure to 2 lpm of waste.

50psi at the first prefilter. ATM the sediment filter is dirty (6 weeks old) and the pressure after the carbon block is 45psi.

-

[Ian Lancaster]

That's exactly why I say there's something wrong with Mike's set-up.  Most likely it's a weeping of raw water past the membrane, otherwise the membrane would work properly.

[Spruce]

That's exactly why I say there's something wrong with Mike's set-up.  Most likely it's a weeping of raw water past the membrane, otherwise the membrane would work properly.

^^^^^^^^^ agree. Mine is a working example that there is an issue somehere.