How long can an R.O unit last??

Fish Keeper82 · 01/17/2015, 07:07 AM

I bought an RO/Di unit from melevs reef about 7 years ago and it is still working. I test the TDS and are still zero. (Yes i checked other sources and the meter if working correctly) so my question is how do you know when its time to change membrane? I dont change my filters as often as i should but still have great results so far. Just wondering what signs to look for.

jeffdenney · 01/17/2015, 07:57 AM

My ro/di setup has been running about a year.. my tds is at 5-8ppm coming out now.. tds going into rodi is about 300-400ppm. (Changes per season)

Im about to change my filters because i know my tap water has phosphates and silicates and those two cause algae like crazy in my high tech planted freshwater tank... in my reef tank, i dont notice as much yet... but im only 4 months in so no crazy lps or sps yet..

Id say i run about 60-80gal a week thru mine for water changes and backup..

So maybe im at like 3500-4000 total gallons thru membrane, who knows on total thru filters as much is dumped as waste.... my first filter is not white by any means anymore... totally brown... i live in Kalamazoo michigan also if that makes any difference on my water..

Dont know if that helps, but i know mine wouldnt last more than about a year..

Fish Keeper82 · 01/17/2015, 08:19 AM

Wow that is high for a year. Melevs claims they have some that have been working 10 years and i believe it. Mine is going on its 8th year and still 0 TDS. Thats hard to believe even for me . My city water TDS are 200-300 range.

Hawkdl2 · 01/17/2015, 08:39 AM

My RO membrane is 6-7 years old and I still get 0 TDS and a good flow rate, though I don't actually measure output flow rate, from 300-350 city water.

azjohnny · 01/17/2015, 09:55 AM

I have heard of them lasting 10 yrs, once the membrane is starting to produce more TDS I would change it

I do change the sediment and carbon filters once a year and the DI when the TDS reaches 0

Paul B · 01/17/2015, 10:04 AM

My Ro is about 15 or 20 years old and the membrane was changed 9 years ago. The DI resins last almost a year.
My RO is under the blue bucket and behind the brine shrimp hatchery. The blue bucket is the resivour and the DI resins are in the acrylic canister to the left of the bucket. Everything is automatic and also keeps the tank fill. Not that silly little tank which has New York creatures in it

Opus123 · 01/17/2015, 03:55 PM

Quote:

Originally Posted by Fish Keeper82

I bought an RO/Di unit from melevs reef about 7 years ago and it is still working. I test the TDS and are still zero. (Yes i checked other sources and the meter if working correctly) so my question is how do you know when its time to change membrane? I dont change my filters as often as i should but still have great results so far. Just wondering what signs to look for.

I assume you mean you are getting zero after the DI, which should always be the case unless it is almost exhausted. To know if the membrane needs to be changed you need to know the rejection rate of your membrane. You then multiply the non-rejection rate times the tds of your water to see what you should be getting. If it is way off then it is time to change the membrane. For example if your is rated at 96% rejection that means 4% gets thru. If your water has a TDS of 200 then multiply that by 4% and that is what the TDS should read after your membrane. It is up to you how much you want to tolerate but the lower the rejection rate the faster our DI will be used up. I just bought a spectrapure with a 99% rejection rate.

ca1ore · 01/17/2015, 04:18 PM

The TDS output of any unit is dependent upon the input rate. Figuring most membranes have a reject rate of 95% plus. For example, my input water is at about 350, give or take, and my post membrane TDS is 5-7.

I suppose it's possible for a 7 year old unit to be still producing 0 TDS water, but strikes me as unlikely unless it gets very little use or input water is off good quality already. I know of no RO unit that produces zero; you need DI for that. If you have been changing the resin then your RO side appears to still work fine.

Personally, I change the RO cartridges annually, and the membrane when TDS starts to keep up (nominally every 24 months). DI resin typically last about 2 months.

Fish Keeper82 · 01/17/2015, 05:10 PM

Negative I have not changed the DI cartridge in years and measured today and got 1 tds basically with no DI since it had changed color indicating it need replacing long ago (3 plus years) i have not changed it because tds are still 0. Must have some minuscule amount in the DI cartridge I guess. I got 1 tds today buy I suspect it's from testing the tap water before and I just dumped the tap then filled with R.O. I did not fully dry the bowl. I had exactly 200 tds on the tap today.

But I do not make a whole bunch of water maybe 60 gallons of r.o a month or so. It is interesting hearing everyone's different experience.

azjohnny · 01/17/2015, 05:28 PM

I use high quality filters in my Spectrapure Maxcap

Sediment-.2 micron Zetazorb ( pleated)
Carbon - .5 micron
Membrane - 99% Spectra Select Plus
1st DI- Maxcap Super DI
2nd DI- Super DI silica buster

I don't buy the color indicating DI cartridges, color changing is not accurate. I have TDS meter's @ the Feed, post membrane, post 1st DI and post 2nd DI. The 1st DI absorbs most of the remaining TDS and the 2nd finishes. You will go through about 4 Maxcap DI catridges before you have to replace the Silica buster

I alsp run my water pressure @ 100 psi, I get about 160 gpd with a 90 gpd membrane and slightly lower TDS than if I ran @ 80 PSI.

IMO I wouldn't run a RO/DI at less than 60PSI

I replace the sediment and carbon filters once a year and the DI when it reaches 1 ppm

My tap water is between 600-700 ppm TDS

Opus123 · 01/17/2015, 05:53 PM

Quote:

Originally Posted by ca1ore

I suppose it's possible for a 7 year old unit to be still producing 0 TDS water, but strikes me as unlikely unless it gets very little use or input water is off good quality already. I know of no RO unit that produces zero; you need DI for that. If you have been changing the resin then your RO side appears to still work fine..

I agree. If there is an RO membrane that would produce zero, then we would all have it. It would save us a lot of money in DI. Best you can do is 99%. I've heard of some really low tds at the tap in certain cities so I could see a zero reading happening if you have a very good membrane and tds below 100. From all the posts I've read over the years the norm seems to be between 200 and 400 for most people. Mine seems to vary depending on the level of the lake.

brycerb · 01/18/2015, 01:48 PM

I killed an RO/DI unit in 24 hrs. My well water pretty much sucks. We don't drink it.

azjohnny · 01/18/2015, 02:44 PM

Quote:

Originally Posted by brycerb

I killed an RO/DI unit in 24 hrs. My well water pretty much sucks. We don't drink it.

I would try a sediment filter with a smaller micron size and make sure the water pressure is up to snuff, with well water you will probably need a booster pump, also elevated CO2 levels can cause you to go through DI much faster

01/17/2015, 07:07 AM	#1
Fish Keeper82 Registered Member Join Date: Jan 2015 Location: Houston, Texas Posts: 691	How long can an R.O unit last?? I bought an RO/Di unit from melevs reef about 7 years ago and it is still working. I test the TDS and are still zero. (Yes i checked other sources and the meter if working correctly) so my question is how do you know when its time to change membrane? I dont change my filters as often as i should but still have great results so far. Just wondering what signs to look for.

01/17/2015, 07:57 AM	#2
jeffdenney Registered Member Join Date: Feb 2014 Posts: 121	My ro/di setup has been running about a year.. my tds is at 5-8ppm coming out now.. tds going into rodi is about 300-400ppm. (Changes per season) Im about to change my filters because i know my tap water has phosphates and silicates and those two cause algae like crazy in my high tech planted freshwater tank... in my reef tank, i dont notice as much yet... but im only 4 months in so no crazy lps or sps yet.. Id say i run about 60-80gal a week thru mine for water changes and backup.. So maybe im at like 3500-4000 total gallons thru membrane, who knows on total thru filters as much is dumped as waste.... my first filter is not white by any means anymore... totally brown... i live in Kalamazoo michigan also if that makes any difference on my water.. Dont know if that helps, but i know mine wouldnt last more than about a year.. __________________ 40b bean animal+20gal sump mixed reef jeabao dc9000 return-swc160 skimmer 250w halide+2x39watt t5ho 5gal fuge-50watt led flood. chaeto,caulaerpa APEX+ Skimz cm122 CaRx

01/17/2015, 08:39 AM	#4
Hawkdl2 Mad Scientist Join Date: Jun 2001 Location: Claremont, Ca Posts: 2,233	My RO membrane is 6-7 years old and I still get 0 TDS and a good flow rate, though I don't actually measure output flow rate, from 300-350 city water. __________________ Larry Current Tank Info: 120g mixed reef.

01/17/2015, 10:04 AM	#6
Paul B Premium Member Join Date: Jun 2002 Location: Long Island NY Posts: 15,549	My Ro is about 15 or 20 years old and the membrane was changed 9 years ago. The DI resins last almost a year. My RO is under the blue bucket and behind the brine shrimp hatchery. The blue bucket is the resivour and the DI resins are in the acrylic canister to the left of the bucket. Everything is automatic and also keeps the tank fill. Not that silly little tank which has New York creatures in it __________________ I used to get shocked when I put my hand in my tank. Then the electric eel went dead. Current Tank Info: 100 gal reef set up in 1971

01/17/2015, 04:18 PM	#8
ca1ore Grizzled & Cynical Join Date: Apr 2006 Location: Stamford, CT Posts: 17,319	The TDS output of any unit is dependent upon the input rate. Figuring most membranes have a reject rate of 95% plus. For example, my input water is at about 350, give or take, and my post membrane TDS is 5-7. I suppose it's possible for a 7 year old unit to be still producing 0 TDS water, but strikes me as unlikely unless it gets very little use or input water is off good quality already. I know of no RO unit that produces zero; you need DI for that. If you have been changing the resin then your RO side appears to still work fine. Personally, I change the RO cartridges annually, and the membrane when TDS starts to keep up (nominally every 24 months). DI resin typically last about 2 months. __________________ Simon Got back into the hobby ..... planned to keep it simple ..... yeah, right ..... clearly I need a new plan! Pet peeve: anemones host clowns; clowns do not host anemones! Current Tank Info: 450 Reef; 120 refugium; 60 Frag Tank, 30 Introduction tank; multiple QTs

01/17/2015, 08:19 AM	#3
Fish Keeper82 Registered Member Join Date: Jan 2015 Location: Houston, Texas Posts: 691	Wow that is high for a year. Melevs claims they have some that have been working 10 years and i believe it. Mine is going on its 8th year and still 0 TDS. Thats hard to believe even for me . My city water TDS are 200-300 range.

01/17/2015, 09:55 AM	#5
azjohnny Registered Member Join Date: Apr 2012 Location: Gold Canyon Posts: 2,914	I have heard of them lasting 10 yrs, once the membrane is starting to produce more TDS I would change it I do change the sediment and carbon filters once a year and the DI when the TDS reaches 0

01/17/2015, 05:10 PM	#9
Fish Keeper82 Registered Member Join Date: Jan 2015 Location: Houston, Texas Posts: 691	Negative I have not changed the DI cartridge in years and measured today and got 1 tds basically with no DI since it had changed color indicating it need replacing long ago (3 plus years) i have not changed it because tds are still 0. Must have some minuscule amount in the DI cartridge I guess. I got 1 tds today buy I suspect it's from testing the tap water before and I just dumped the tap then filled with R.O. I did not fully dry the bowl. I had exactly 200 tds on the tap today. But I do not make a whole bunch of water maybe 60 gallons of r.o a month or so. It is interesting hearing everyone's different experience.

01/17/2015, 05:28 PM	#10
azjohnny Registered Member Join Date: Apr 2012 Location: Gold Canyon Posts: 2,914	I use high quality filters in my Spectrapure Maxcap Sediment-.2 micron Zetazorb ( pleated) Carbon - .5 micron Membrane - 99% Spectra Select Plus 1st DI- Maxcap Super DI 2nd DI- Super DI silica buster I don't buy the color indicating DI cartridges, color changing is not accurate. I have TDS meter's @ the Feed, post membrane, post 1st DI and post 2nd DI. The 1st DI absorbs most of the remaining TDS and the 2nd finishes. You will go through about 4 Maxcap DI catridges before you have to replace the Silica buster I alsp run my water pressure @ 100 psi, I get about 160 gpd with a 90 gpd membrane and slightly lower TDS than if I ran @ 80 PSI. IMO I wouldn't run a RO/DI at less than 60PSI I replace the sediment and carbon filters once a year and the DI when it reaches 1 ppm My tap water is between 600-700 ppm TDS

01/18/2015, 01:48 PM	#12
brycerb Registered Member Join Date: Jan 2009 Location: Isle of wight, VA Posts: 541	I killed an RO/DI unit in 24 hrs. My well water pretty much sucks. We don't drink it. __________________ -Luckily, my wife is reef safe so I can use my normal income for this hobby. -My cichlids love RO waste! Current Tank Info: 7.5 gallon box with water in it.