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wesheltonj
Sat, 3rd Jan 2009, 12:30 PM
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
Sat, 3rd Jan 2009, 12:41 PM
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 waste:perified water ratio that is too low (e.g., 1:1).

Those are the first three things that come to mind.

Russ
wesheltonj
Sat, 3rd Jan 2009, 01:49 PM
It must have been #1, I rechecked and was down to 19.
BuckeyeHydro
Sat, 3rd Jan 2009, 02:00 PM
So that leaves you with a 90% rejection rate. Do you have a 100 gpd membrane?
wesheltonj
Sat, 3rd Jan 2009, 02:39 PM
no 75 gal
BuckeyeHydro
Sat, 3rd Jan 2009, 03:44 PM
That's not very good for a 75 gpd. Low pressure? Inaccurate TDS measurement?
wesheltonj
Sat, 3rd Jan 2009, 04:03 PM
I will retest.
wesheltonj
Sat, 3rd Jan 2009, 09:04 PM
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
Sat, 3rd Jan 2009, 09:51 PM
What is your pressure?
Bill S
Sun, 4th Jan 2009, 02:41 PM
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.
DrMark
Sun, 4th Jan 2009, 03:38 PM
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.


these are good #'s are they not?
wesheltonj
Sun, 4th Jan 2009, 03:52 PM
Looks like according to BFS I can be doing better. Not time today to try, to big of to do list. Looks like next week to increase pressure.
BuckeyeHydro
Sun, 4th Jan 2009, 04:16 PM
these are good #'s are they not?

Its the RO performance (90% rejection) I'm concerned about. The 0 tds out of the DI is fine.

So his livestock should be happy, but he may burn through his DI resin faster than we'd like.