Ro filter replacement

kevin j. · 02/23/2018, 11:28 AM

So I purchased a used rodi unit. The seller says the unit is eight months old. How can I test the ro membrane to see if it needs replacement. Thanks in advance.

mcgyvr · 02/23/2018, 11:34 AM

Run it..
And measure the TDS in and TDS out..
If it falls below its rated percentage range then replace it..
Many are like 97%.. some 93%,etc...

Unless they did something totally stupid though a RO membrane should last like 3-5 years..

JP Reef · 02/23/2018, 11:34 AM

If it dried out I would replace it, but the easy answer is to measure TDS before and after. Make sure you have a sediment and carbon cartridge in front of the membrane else you will damage it.

kevin j. · 02/23/2018, 11:39 AM

What kind of tds reading am I looking for after the ro membrane?

mcgyvr · 02/23/2018, 12:48 PM

Quote:

Originally Posted by kevin j.

What kind of tds reading am I looking for after the ro membrane?

Depends on the rejection rate of your membrane.. Whos ro/di unit is it?

For example..
With a membrane with a stated 97% rejection rate the output (after RO) should be close to 97% less than the input (before RO)..

kevin j. · 02/23/2018, 01:24 PM

It's a marine depot kleanwater 75 gpd unit. Thanks for everyone input so far.

mcgyvr · 02/23/2018, 06:09 PM

If its less than 90-93% replace it..

Bent · 02/23/2018, 06:48 PM

I don’t trust people and membranes aren’t very expensive I’d just replace it.

DesertReefT4r · 02/23/2018, 08:12 PM

Yeah just replace all the filters and DI resin and start fresh. Call Spectrapure or BRS for a good set of filters. Having a local water report helps a lot when setting up a ro unit and buying filters.

smoothmove · 02/24/2018, 09:47 AM

amazon. ro/di for $60-$100. Would you buy a used coffee filter? I don't chance my reef to anything..

you can also buy the individual pieces if needed.

Spectrapure is the best RO/DI I have ever owned.

02/23/2018, 11:28 AM	#1
kevin j. Registered Member Join Date: Nov 2004 Location: Broadview Heights Posts: 75	Ro filter replacement So I purchased a used rodi unit. The seller says the unit is eight months old. How can I test the ro membrane to see if it needs replacement. Thanks in advance.

02/23/2018, 11:34 AM	#2
mcgyvr Registered Member Join Date: Sep 2003 Location: North Carolina Posts: 20,050	Run it.. And measure the TDS in and TDS out.. If it falls below its rated percentage range then replace it.. Many are like 97%.. some 93%,etc... Unless they did something totally stupid though a RO membrane should last like 3-5 years.. __________________ Who me?

02/23/2018, 06:09 PM	#7
mcgyvr Registered Member Join Date: Sep 2003 Location: North Carolina Posts: 20,050	If its less than 90-93% replace it.. __________________ Who me?

02/23/2018, 06:48 PM	#8
Bent I got nothin' Join Date: Nov 2004 Location: The anals Posts: 6,420	I don’t trust people and membranes aren’t very expensive I’d just replace it. __________________ Quitters never lose. [QUOTE=CStrickland]Who gets mad at a starfish?[/QUOTE] Current Tank Info: 75g DT, 30G refugium, 10g chaeto tank, 50g stock tank basement sump

02/23/2018, 08:12 PM	#9
DesertReefT4r Registered Member Join Date: Sep 2015 Location: Mesa Az Posts: 771	Yeah just replace all the filters and DI resin and start fresh. Call Spectrapure or BRS for a good set of filters. Having a local water report helps a lot when setting up a ro unit and buying filters. __________________ Tank history 29g tropical ,55g cichlid tank, 20H softy reef, 29g mixed reef, 20H brackish goby & puffer tank, 55g mixed reef, 6g Nanocube softy lps reef, 40B sps reef, 75g sps reef, 75g sps reef in bu Current Tank Info: 75g sps reef build in the works.

02/23/2018, 11:34 AM	#3
JP Reef Registered Member Join Date: Feb 2013 Location: Greensburg, PA Posts: 207	If it dried out I would replace it, but the easy answer is to measure TDS before and after. Make sure you have a sediment and carbon cartridge in front of the membrane else you will damage it.

02/23/2018, 11:39 AM	#4
kevin j. Registered Member Join Date: Nov 2004 Location: Broadview Heights Posts: 75	What kind of tds reading am I looking for after the ro membrane?

02/23/2018, 01:24 PM	#6
kevin j. Registered Member Join Date: Nov 2004 Location: Broadview Heights Posts: 75	It's a marine depot kleanwater 75 gpd unit. Thanks for everyone input so far.

02/24/2018, 09:47 AM	#10
smoothmove Registered Member Join Date: Mar 2002 Location: RockWall, Texas Posts: 464	amazon. ro/di for $60-$100. Would you buy a used coffee filter? I don't chance my reef to anything.. you can also buy the individual pieces if needed. Spectrapure is the best RO/DI I have ever owned. __________________ 80 gallon Deep Blue Rimless, 5 Kessil A160's Tuna Blues, Converted AquaC EV 400 w/ Sedra 15000, Jebao 36 watt UV, Jebao DCT12000, 75 gallon sump