RO/DI Unit & TDS Meter Question

Brent Thomann · 03/22/2006, 10:57 AM

I bought a RO/DI unit a while ago, this one -http://cgi.ebay.com/ws/eBayISAPI.dll...tem=7722364022

I tested the water coming out of the unit with a TDS meter and it read 0. After several month of using it in now reads 14. Does this mean its time to change the filters or resin? Is 14 bad?

Entropy · 03/22/2006, 11:01 AM

Yes and maybe. Depends on what the 14ppm is, but your DI is exhausted for sure, and your filters probably need changing as well.

impur · 03/22/2006, 12:27 PM

What is the TDS of your tap water? That may have something to do with the life of your filters. I have the same unit and have only changed the DI resin once in 18 months (about 4 months ago)and i'm still getting 0 TDS.

twkenny · 03/22/2006, 01:33 PM

Quote:

Originally posted by humpn247
I bought a RO/DI unit a while ago, this one -http://cgi.ebay.com/ws/eBayISAPI.dll...tem=7722364022

I tested the water coming out of the unit with a TDS meter and it read 0. After several month of using it in now reads 14. Does this mean its time to change the filters or resin? Is 14 bad?

I have that same unit and found that the DI resin settled a bit in the chambers, allowing RO water to get by without passing through the resin completely.
If your incoming TDS in 140 or greater, I'd imagine the DI is the problem.
You should change the sediment and carbon at 6 months anyway, so you may want to order some resin and filters from someone....top off the resin and see what happens. I took mine off and packed it down. It went back to 0.

Edit....this got a bit old, so I ordered a vertical, add on DI housing from www.purelyh2o.com. It was under $30.

Brent Thomann · 03/22/2006, 01:46 PM

Quote:

Originally posted by impur
What is the TDS of your tap water? That may have something to do with the life of your filters. I have the same unit and have only changed the DI resin once in 18 months (about 4 months ago)and i'm still getting 0 TDS.

>What is the TDS of your tap water?
I'm pretty sure it read 120, good bad? Using THIS TDS Meter

I think I might be getting a little channel in my DI chambers. The resin is starting to turn colors a little on the one end too.

My sediment filter (first one) is starting to change colors as well (yellowish).

Would you suggest changing filters then? When I bought the unit I purchased all replacement filters and resin (not membrane). Didn't think I was going to need to change them after a 3 months though, if thats what you think I need to do.

It produces about 1 gallon a day for my setup w/ by weekly 15% water changes.

Brent Thomann · 03/22/2006, 02:55 PM

Quote:

Originally posted by twkenny

Edit....this got a bit old, so I ordered a vertical, add on DI housing from www.purelyh2o.com. It was under $30.

so you added an additional (thrid) DI chamber? was it this one- http://www.purelyh2o.com/cart.php?ta...category_id=13

twkenny · 03/22/2006, 03:10 PM

I took off the horizontal ones when it was time to change resin and added that one you listed.

Brent Thomann · 03/22/2006, 03:17 PM

Quote:

Originally posted by twkenny
I took off the horizontal ones when it was time to change resin and added that one you listed.

I take it that one is better than the two that come on it?

Did you lose any pressure? Right now I have the unit in my basement with an 80' line going upstairs connected to a float switch in my sump for my auto-top off. Works Real nice, no power needed. Just ran the waterline behind my baseboards when I got upstairs.

You don't have a picture handy of how you install it do you?

twkenny · 03/22/2006, 03:21 PM

Not that I know of. I would think the DI does not create too much pressure.
The two horizontal ones got a bit aggrivating to me. As the resin settled, water would get past and my TDS reading would go up some. Not the end of the world, but it should be 0 or so. The replacement unit uses a standard vertical type cartridge and won't need to be topped off or messed with. So now I run sediment, carbon, carbon, RO, then DI.
I have mine hooked to a float in my sump as well. I love it.
No pic handy, just put the line going into the first DI canister into the new vertical chamber, and move the line from the output of the second canister to the output side of the new vertical. Nothing to it.

Reefmaniac1 · 03/22/2006, 04:35 PM

Bypass of a horizontal DI bed is very common...and a PITA.

twkenny · 03/22/2006, 08:08 PM

Agreed. Hence the vertical DI addition.

03/22/2006, 10:57 AM	#1
Brent Thomann Registered Member Join Date: Oct 2005 Location: T. Tonawanda, NY Posts: 1,825	RO/DI Unit & TDS Meter Question I bought a RO/DI unit a while ago, this one -http://cgi.ebay.com/ws/eBayISAPI.dll...tem=7722364022 I tested the water coming out of the unit with a TDS meter and it read 0. After several month of using it in now reads 14. Does this mean its time to change the filters or resin? Is 14 bad?

03/22/2006, 11:01 AM	#2
Entropy Texas Reefer Join Date: May 2003 Location: Round Rock, TX Posts: 13,656	Yes and maybe. Depends on what the 14ppm is, but your DI is exhausted for sure, and your filters probably need changing as well. __________________ Rich Overton 150G cube FOWLR, 30g sump, ReefKeeperII, 3x Koralia 1400's, QuiteOne 3000, Reef Octopus DNWB150, 4x 30w Par38 LED. Current Tank Info: 36x36x27 150g

03/22/2006, 12:27 PM	#3
impur Registered Member Join Date: Jul 2003 Location: Eugene, OR Posts: 4,262	What is the TDS of your tap water? That may have something to do with the life of your filters. I have the same unit and have only changed the DI resin once in 18 months (about 4 months ago)and i'm still getting 0 TDS. __________________ Great spirits often encounter violent opposition from mediocre minds. Current Tank Info: 75gal, 20gal sump, 6-54w T5 TEK

03/22/2006, 04:35 PM	#10
Reefmaniac1 Registered Member Join Date: Feb 2004 Location: Durham, NC Posts: 2,580	Bypass of a horizontal DI bed is very common...and a PITA. __________________ "Stupidity is not necessarily punishable by violence. Although, there are days when I wish it were." - Solomon Short Current Tank Info: None due to disaster...and moving.

03/22/2006, 03:10 PM	#7
twkenny Registered Member Join Date: Jan 2004 Location: Sunny South Posts: 1,081	I took off the horizontal ones when it was time to change resin and added that one you listed.

03/22/2006, 03:21 PM	#9
twkenny Registered Member Join Date: Jan 2004 Location: Sunny South Posts: 1,081	Not that I know of. I would think the DI does not create too much pressure. The two horizontal ones got a bit aggrivating to me. As the resin settled, water would get past and my TDS reading would go up some. Not the end of the world, but it should be 0 or so. The replacement unit uses a standard vertical type cartridge and won't need to be topped off or messed with. So now I run sediment, carbon, carbon, RO, then DI. I have mine hooked to a float in my sump as well. I love it. No pic handy, just put the line going into the first DI canister into the new vertical chamber, and move the line from the output of the second canister to the output side of the new vertical. Nothing to it.

03/22/2006, 08:08 PM	#11
twkenny Registered Member Join Date: Jan 2004 Location: Sunny South Posts: 1,081	Agreed. Hence the vertical DI addition.