RO/DI Problem

[serpentman]

I have a 5-stage RO/DI system. I recently bought a TDS meter and checked it out. It is showing a reading of 100-120 on the output which I believe is too high. Any ideas on the cause?

Also, is the resin chamber in the DI unit supposed to be full or half full. Mine came only half full..

 

[old salty]

I don't know what unit you are using, but I'll try and help.

What water pressure are you seeing (from your source)? Are the valves in their correct positions (DI bypass, RO flush, etc..)? I keep my DI chamber completely full. Actually I sort of pack the beads in the filter as this seems to work the best.

 

[AZDesertRat]

You need to provide much more information. What unit is it, what membrane, does it have a flush valve, is the flush valve in the correct position, what is your tap water TDS, RO only without DI TDS, RO/DI TDS, pressure, age of unit etc. If its new I have asneaking suspicion the membrane is not seated correctly in the housing but thats only a guess at this point.

 

[serpentman]

Thanks guys, here is the information:

Manufacturer: Dvoneb Aqua
Unit Age: 1 month
Membrane: ?
Flush Valve: Yes (is in correct position)
Pressure: 58psi
Tap Water TDS: 220
After RO (before DI): 86
After DI: 109

I also tested the TDS meter with Distilled Water which read 000

Ironically, it tests higher after my DI unit? How can that be?

 

[AZDesertRat]

If I am not mistaken that is one of the units that uses a Chinese knock off membrane and not a name brand like Dow Filmtec, Applied or GE. There could be a problem with the membrean but frst I would unscrew the RO housing and re seat the membrane to make sure there is no bleed by.
As for the TDS being higher after the DI, do you have the small post carbon filter on it? If so either throw it away or only use the post carbon after RO only without DI for drinking water. GAC carbon will raise the TDS if used after DI.

 

[serpentman]

You hit the nail on the head. The carbon filter was inline after the prefilter but before the RO. It most likely raised the TDS levels way high before hitting the RO because I removed it and let it run for 5 mins and just got 000 on the TDS meter!

Thanks for the help guys!

 

[smleee]

<a href=showthread.php?s=&postid=7437788#post7437788 target=_blank>Originally posted</a> by serpentman
The carbon filter was inline after the prefilter but before the RO.

You still need that filter; AZ was talking about systems that have a post-RO carbon filter for drinking water.

eee

 

[serpentman]

I spoke too soon. Tested again. TDS is down by 15-20 however still averaging around 100

Why would you need it before the RO?

 

[AZDesertRat]

The pre carbon filter is what removes the chlorine so it does not destroy the membrane. You probably have a small horizontal filter on top next to the membrane that contains carbon, thats the one I am referring to.

 

[serpentman]

You are right, I completely missed the other carbon filter. Well, you were also right about the membrane not seating correctly. Your comment got me thinking. I have noticed that the output almost equalled the waste output which I know shouldn't be. After almost a whole roll of teflon tape I got it to seat properly. Output flow is significantly reduced and I am getting consistant readings of 4-8 on the TDS, which I believe is within normal parameters.

Lesson learned, you get what you pay for. At least I am able to salvage the membrane. Thanks again for your help guys.

How often should the carbon filter be changed?

 

[AZDesertRat]

Prefilters and carbons should be changed every 6 months. DI should be changed when you consistently see a TDS of 3 or 4. RO membranes should last 2 to 3 years.

 

[TimFountain]

<a href=showthread.php?s=&postid=7438106#post7438106 target=_blank>Originally posted</a> by serpentman
You are right, I completely missed the other carbon filter. Well, you were also right about the membrane not seating correctly. Your comment got me thinking. I have noticed that the output almost equalled the waste output which I know shouldn't be. After almost a whole roll of teflon tape I got it to seat properly. Output flow is significantly reduced and I am getting consistant readings of 4-8 on the TDS, which I believe is within normal parameters.

Lesson learned, you get what you pay for. At least I am able to salvage the membrane. Thanks again for your help guys.

How often should the carbon filter be changed?

With DI you really should be getting 0 at the output on a brand new setup. When I get >6, I change out the DI....