Is zero tds possible with RO only?

Delphinus · #1 11-02-2009, 04:22 PM

Looks like you have your answer already but since this is a topic I feel I have a tiny bit of knowledge on, I'm compelled to post anyhow.

Yes 0 TDS is possible in Calgary water with RO alone, but typically it's better still to use the DI because there tends to be TDS surges and the DI will catch those. It depends on the membrane, some brands have better rejection rates than others. With the membrane I have right now, the best I can get after a 20 minute flush is about 3-4 TDS (it will go down to zero after about an hour or so). The membrane I had before had such a great rejection rate that it would be zero TDS within a 2 minute flush. I've kept my old one so I can remember what kind to order when I've had enough of this one.

Keep an eye on your RO output TDS, when it stops going below 10 on a 5 minute flush it's pretty much time to let it go. Expect to replace them around 12 to 18 months around here.

If you don't have a flush kit, get one.

And and whatever you do, even if you have a auto-shutoff on your RO, don't hook it up to a float valve or float switch in your tank, because constant on/off's are the fastest way to kill a membrane. They are designed for long runs, so turn it on, flush it for 2-5 minutes or whatever, then let it run for say 12 hours. Shut it off and leave it off until you need more again.

The ONLY thing those shutoff kits should be used for is preventing overfills. As soon as whatever it is you're filling is full, turn off the source water.

lastlight · #2 11-02-2009, 04:41 PM

Lance and JDigital that is GROSS. I've taken slight offense guys...just a casual warning but please keep my threads on-topic and clean.

Yeah on my last tank I ran the ro/di straight to a float valve in my tank and battled algae like you wouldn't believe. Bet it was the creep. I have to install a float into my water-change top tank after I can pull the ro/di line out of the display.

I actually cut the autoshutoff stuff out of the unit as they are cheap and always fail. I bought a backup but the creep issue drove me to get rid of it altogether and besides the float valve in my reservoir I also have it plumbed with an emergency drain. I am buying an electronic solenoid and putting it on a timer to run for a set period of time nightly. Right now it's on full-manual. Meaning I gotta keep an eye on it!

The unit had a flush kit but since my old unit didn't have a flow restrictor I didn't even know what it was. When I had issues getting the thing to not dump waste water like a banshee I realized what I had removed and put it back in place. I need to add a new valve in to do flushes still.

Lance · #3 11-02-2009, 04:52 PM

[quote=lastlight;460290]Lance and JDigital that is GROSS. I've taken slight offense guys...just a casual warning but please keep my threads on-topic and clean.

My apologies.

I misinterpreted your post, thought it was a joke.

mike31154 · #4 11-02-2009, 05:18 PM

WRT the auto shut off valve, I haven't been able to get mine to work properly at all either and would never trust the thing. After some small mishaps, I only run the system manually and set the timer on the kitchen stove to remind me to check it periodically. No way I'd leave the house with the system running.

lastlight · #5 11-02-2009, 05:50 PM

Lance you silly arse!

I was kidding. Seriously man! Have I not established sufficient levels of silly to make that obvious? Dammit!

Lance · #6 11-02-2009, 06:12 PM

Quote:

Originally Posted by lastlight

Lance you silly arse!

I was kidding. Seriously man! Have I not established sufficient levels of silly to make that obvious? Dammit!

Well, it did kind of surprise me.

: Thought maybe you got up on the wrong side of the bed this morning.
Back to topic: Brett, I use the BRS top-off valve as well as a timer from Rona. I figure this ensures no accidents and will cover my silly arse.

lastlight · #7 11-02-2009, 06:16 PM

Dude when you're filling a tank that's been 1.5 yrs in the making there is no wrong side of the bed. If/when I battle algae again...well then look out!

I likely will try and connect the new shutoff valve i bought if i can remember how just to waste a little less water when I ignore the stove alarm a few minutes.

JDigital · #8 11-02-2009, 06:26 PM

Quote:

Originally Posted by lastlight

Lance you silly arse!

I was kidding. Seriously man! Have I not established sufficient levels of silly to make that obvious? Dammit!

Obviously not! I didn't have "gross" thoughts when I made my post..

lastlight · #9 11-02-2009, 06:38 PM

Oh crap. Looking back you DIDN'T have any gross thoughts. Haha just Lance and I.

But seriously guys...howzabout that tds?

lastlight · #10 11-02-2009, 05:52 PM

Quote:

Originally Posted by mike31154

I only run the system manually and set the timer on the kitchen stove to remind me to check it periodically

Now that's a lot cheaper than the solenoid which could still fail. I'm doing this. Even if I somehow don't notice the stove going off my wife will!