[jetmaster]

newbe needs advise on tds readings on my ro 40/40.i have purchased a second hand system and my readings are at 48 psi water pressure tds at tap 66 out of ro 17 and waste reading is 192 is this to high.any help appreciated.

[Ian Lancaster]

Hi Jetmaster, and welcome

Depending on what membrane is in your 40-40, if your tap water is 66, the output should be 0.  48psi is plenty for a low pressure membrane.  Tds of waste is irrelevant.  Pure to waste ratio is important, it should produce about one and a half to two litres of waste to every litre of pure.

If you have that right it could be that your membrane is well used, but at 17ppm all you need to do is pass the water through a De ionising vessel and it will be fine.

Resin for the deioniser costs about £70 per 25lt and will last you a couple of years.

[wfp master]

Tds at tap 66 no need for ro d/i only.my tap tds is 78ish d/i only less hassle.

[home6442]

Have you changed your pre filters.
A cloged pre filter can lower the pressure going through the
r.o. and could cause the tds to rise.
Flush the r.o. for 30 mins after changing the pre filters.
You could also try running more water to waste.

[jetmaster]

hi thanks for reply's will have a look at what membrane i have thanks rob.