Membrane Help

[wesheltonj]

I replaced my membrane about 4-5 months ago. Today I changed out the DI resin as the water out was up to 1 to 2 ppm. I checked the ro out water and its at 100 ppm, the water in only @ 195. What am I doing wrong.

[BuckeyeHydro]

You might have a couple of things going on.

1. When an RO system starts up, and for a period of a few minutes on residential scale systems, you get a pulse of not-so-clean water from the system. If you didn't let the system run for a while before you took your sample, that might be the cause.

2. If you weren't careful in how you took your measurement, it may have caused inaccurate readings. For instance, did you use an absolutely clean container to take the sample you measured?

3. Your RO membrane may not be fully installed/seated. If this is the case, you'll have waste water that ends up coming out of the RO water port. If a membrane is not fully seated, you can usually tell by a wasteerified water ratio that is too low (e.g., 1:1).

Those are the first three things that come to mind.

Russ

[wesheltonj]

It must have been #1, I rechecked and was down to 19.

[BuckeyeHydro]

So that leaves you with a 90% rejection rate. Do you have a 100 gpd membrane?

[wesheltonj]

no 75 gal

[BuckeyeHydro]

That's not very good for a 75 gpd. Low pressure? Inaccurate TDS measurement?

[wesheltonj]

I will retest.

[wesheltonj]

I took some more measurements after making 25 gallons of water today. 188ppm in and 23ppm out. 0 after DI?

I can increase the water pressure next weekend and see if the number are any better.

[BuckeyeHydro]

What is your pressure?

[Bill S]

Make sure to check #3 - it's REAL easy to make that mistake. It takes a bit of pressure to make sure the membrane seats completely.