RO/DI Filters: How often is too often to have to replace them?

[alton]

My chloramines is up to 4ppm sometimes so I know what high levels are, wait till BRS runs a discount and buy the chloramine blaster so you can stop worrying about burning up membranes and DI with total chlorine. Since I also have a pool I use the test strips all the time on both RO/DI and Pool

 

[Tarponwriter]

I run a seven stage system plumbed directly to my display tank. I change sediment and carbon every six months. My tap water depletes the cation only canister in about six months anyway. I rinse my membrane once a week for 5 minutes with the bypass valve and it’s going on 2 years old now. I have not had to change my anion in 1.5 years. My system makes about 30 gallons of RO/DI a week

 

[Dvanlier05]

I have a BRS 7 stage, change the RO membrane every year. Filters and media get replaced every other month. I know I can go longer between changes but filters and media are cheap. I like the peace of mind knowing my water is good.

 

[Buckeye Hydro]

From our FAQ's:

Reverse Osmosis Filters | RODI Systems | Commerical Water Filtration System - Buckeye Hydro

Offering only the best in water filtration systems and reverse osmosis filters, Buckeye Hydro has been helping their customers experience clean, clear water since the 90's.

www.buckeyehydro.com

A good rule of thumb is to replace your sediment filter and carbon block after six months. A more precise way to maximize the usable life of these two filters is to use a pressure gauge to identify when pressure reaching the membrane starts to decline. This is your indication one or more of the prefilters (all the filters that touch the water before it reaches the RO membrane) is beginning to clog.

Also be cognizant of the chlorine capacity of the carbon block. A good 0.5 micron carbon block for example will remove much of the chlorine from 20,000 gallons of tap water presented at 1 gpm. Some original equipment suppliers commonly provide carbon cartridges rated at 2,000 to 6,000 gallons. Remember that all the water you process, both waste water and purified water, goes through the carbon block.

Regarding your RO membrane and DI resin, use your total dissolved solids (TDS) meter to measure, record, and track the TDS (expressed in parts per million [ppm]) in three places: 1) tap water, 2) after the RO but before the DI, and 3) after the DI.

The TDS in your tap water will likely range from about 50 ppm to upwards of 1000 ppm. Common readings are 100 to 400 ppm. So for sake of discussion, let's say your tap water reads 400 ppm. That means that for every million parts of water, you have 400 parts of dissolved solids. How do we go about getting that TDS reading down to somewhere near zero?

If you do some experimenting with your TDS meter, you'll note that your sediment filter and carbon block do very little to remove dissolved solids. So with your tap water at 400 ppm, you can measure the water at the “in” port on your RO membrane housing and you'll see it is still approximately 400 ppm.

The RO membrane is really the workhorse of the system. It removes most of the TDS, some membranes to a greater extent than others. For instance, 100 gpd Filmtec membranes have a rejection rate of 96% (i.e., they reject 96% of the dissolved solids in the feed water). So the purified water coming from your 100 gpd membrane would be about 16 ppm (a 96% reduction). Filmtec 75 gpd (and below) membranes produce purified water (a.k.a. “permeate”) more slowly, but have a higher rejection rate (96 to 99%). The lifespan of an RO membrane is dependent upon how much water you run through it, and how “dirty” the water is. Membranes can function well for a year, two years, or more. To test the membrane, measure the TDS in the water coming into the membrane, and in the purified water (permeate) produced by the membrane. Compare that to the membrane’s advertised rejection rate, and to the same reading you recorded when the membrane was new. Membranes also commonly produce purified water more slowly as their function declines.

After the RO membrane, water will flow to your DI housing. DI resin in good condition will reduce the TDS in the RO water down to 0 or 1 ppm. When the DI output starts creeping up from 0 or 1 ppm, your resin needs to be replaced. Sometimes you'll hear people complain that their DI resin didn't last very long. Often the culprit is a malfunctioning RO membrane sending the DI resin high TDS water. This will exhaust the resin quicker than would otherwise have been the case. Sometimes the problem is poor quality resin – remember that all resins are not created equal.

Additionally, don’t forget to sanitize the entire system at least once per year, and wash and lube your housing o-rings with food-grade silicone grease every filter change.

Russ

 

[lefkonj]

Not a fair comparison for me. My house has a whole house water filter so the filters on my system last longer because the water is already filtered somewhat.

 

[Fishinabarrel]

7 months and haven't changed a dang thing.......TDS = 1. Time to get off my lazy butt.

 

[Proteus Meep]

As a Nano Reefer currently with a 130 litre all in one...

RO Membrane about every 5 years, but not because it needs it because of a TDS rise, at that point I figure it's just time to freshen it up

Micron Filter and Carbon- Yearly but not because they are blocked or darkened, again i just figure it's time to freshen them

Di Resin, about every 4-5 months as soon as the TDS reads 1, only use one of the smaller add on DI units holding about a 300ml resin

 

[LPS Bum]

I only have to replace my RODI canisters (sediment, carbon and DI resin) every 12 months. And I could probably squeeze a little more life out of them, but 12 months seems to be the sweet spot.

My water only averages about 50 TDS (never seen it higher than 63, and I've seen it in the 40s plenty of times), and I only make 10 gallons a week (I use it exclusively for my reef tank tops off and weekly water changes, but my large FOWLR still gets decholorinated tap water).

So far I haven't had to replace my TFC membrane, but that's likely coming next year.

 

[eric.tech]

I change my filters on a as needed basis. If sediment looks dirty, it gets changed. If chlorine is detected, time for carbon! DI resin? When it’s exhausted.

Also, I gather up my old DI resin, regenerate it, and re-use it.
My TDS is around 350-430ish.

 

[SKEETER1978]

I run a 7 stage with 1 sed.. 2 carbon a 100gpd ro mem and 3 di canisters... 1 is anion (blue)... 1 is cation(purple) and 1 mixed.... for some reason i go threw the blue anion 3x faster than the purple... and when i get 1-2 tds i grow algae and red slime. My tap water is 350tds and 15 after ro and has to be 0 after di. I change my sed and carbon about every 9 months and my ro mem is about 1.5 yrs old now and still working... blue di resin goes fast maybe every 400gals
I use triton method and do not do allot of water changes... I make more top off water

 

[Buckeye Hydro]

Not a fair comparison for me. My house has a whole house water filter so the filters on my system last longer because the water is already filtered somewhat.

What is your whole house filter? What media is inside it?

 

[Jax15]

I go through DI resin very fast. Probably every 3 months I need to replace it, using a BRS 5-stage premium kit.

That's to account for a 120g TWV system, both evaporation and ~1.8% daily AWC.

I replace the carbon and sediment filters maybe every 8-12 months, and the RO filter every 2.5-3 years. Does that sound about right to ya'll?

 

[Jax15]

I run a 7 stage with 1 sed.. 2 carbon a 100gpd ro mem and 3 di canisters... 1 is anion (blue)... 1 is cation(purple) and 1 mixed.... for some reason i go threw the blue anion 3x faster than the purple... and when i get 1-2 tds i grow algae and red slime. My tap water is 350tds and 15 after ro and has to be 0 after di. I change my sed and carbon about every 9 months and my ro mem is about 1.5 yrs old now and still working... blue di resin goes fast maybe every 400gals
I use triton method and do not do allot of water changes... I make more top off water

Sounds like you should have 2X chambers of anion (blue), and 1 chamber of mixed bed. You'd have to change less often, and the mixed bed should have more than enough cation sounds like. Just a thought.

 

[Spieg]

I rarely do water changes so top off water is what I use RODI for the most. Also have pretty good source water so filters can last me for 3 years or more.

 

[Biglew11]

My system has been upgraded in stages to a 7 stage system w/booster pump and 2 100 GPD ro membranes in water saver. 3 di canisters 1 cation 1anion and 1 mixed.

My tds at the faucet is around 130 to 150. I change the pre filters about once a year. I haven't changed the ro membranes yet, I'm still getting 2-3tds after the two membranes combine. I go through anion much faster than cation. I change out the anion when I start to get 1-2 tds between the 2nd and third stage. I change out the mixed bed at about 1.5 years or when it's about 75 percent used up.

 

[JHUMike]

Depending on the TDS of your water, how much water you're making and other factors you could be replacing your RO/DI filters more often than you want to. But how often is too often? Let's poll the community today and see what others have to say!

1. How often do you have to replace your RO/DI filters?

2. What's the biggest factors that come into play in exhausting your RO/DI filters?

3. How high is your home TDS?

I replace sediment very frequently; Carbon and DI every 4 months and RO over 1 yr (1.5 or so).

 

[design.maddie]

I have to change my DI every 3 months and my sediment and carbon every 6 months. I have all sorts of junk in my tap water including CO2, yippie

 

[Aheinz]

I say other as I think it widely depends on local supply, and for my mind sake when I replace I just replace all

 

[GoVols]

Replace the ro membranes when the tds starts to rise after the ro membranes, before the di resin chambers.

 

[West1]

Great thread!

I change membrane every 6-8 months.
Sediment and carbon once a month or approximately every 200-250 gallons.
Idk my tap TDS.

I need to read everyone’s post, I may be going overboard!

How is everyone testing tds at each stage?
Does each stage have a T w/a shutoff valve or is everyone going through the hassle of removing the IN-Line and testing?