RO Unit Question

[RayAllen]

Today I changed my filters on my RO Unit- LONG LONG OVER DUE

I changed all three filters and the RO Membrane.

All the filters have a specified 6 month life span, but the RO membrane does not list the longivity.

What is the life span of a RO Membrane?

Note: Im going to ad a DI canister to my RO system soon.

[Gseclipse02]

i was told the membrane will last 3-5 years IF the other filters are kept up with which means your TDS doesnt ever get high

[Europhyllia]

I thought it was 2 years

[Gseclipse02]

you could be right its been a whiole since i was looking RODI stuff up

[Gseclipse02]

your right

"Membranes can function well for a year, two years, or more"

[RayAllen]

Cool, good to know. I told my wife to help me remind me to buy filters every six months because we also use it for drinking/cooking water. She will be happy that I dont have to replace the membrane for at least 2yrs. The membrane cost me $50 by itself today. The other filters ranged in price from $12-$22.

[RayAllen]

I do have another question what is the typical gallons a RO or RO/DI will make in a day if allowed to run. It takes mine forever just to make 5gallons.

[Gseclipse02]

So many variables but I make about 5 in 1 hour 20 mins …

[jrsatx20]

Takes me about 3 hrs to make five gallons. Going a lil faster now that it is hot out. During the winter I only have drips if left running. Right now its a steady stream. Mine is a 25gallon per day.

[RayAllen]

Cool! Took me over a hour for 5 gallons as well so I guess im on track!

Ive had this RO unit installed in the house for 3 yrs but its really only been used for drinking and cooking with the occassional gallon or two top off on the nano. Not so much for water changes so thats why after all this time im asking these questions. Really just tired of buying water from the store, so I thought its time to take advantage of having what I already have and change the membrane and filters.

Tonight i have figured out when I want to do a water change its best to get the water started days in advance just so that I have enough, lol.

[jrsatx20]

That's what I do ray. I only have a ro unit. Had tds tested and came out at 34. Not to bad. I know di can be added but im cheap. I've never had problems using just ro water.

[Big_Pun]

yes plan ahead or get a big storage container, I have a 55g.barrel I use, also if intrested I have a 15 gallon barrel I'm not using anymore for sale pm me if interested

[RayAllen]

Takes me about 3 hrs to make five gallons. Going a lil faster now that it is hot out. During the winter I only have drips if left running. Right now its a steady stream. Mine is a 25gallon per day.

Yep once I get past the first initial 3 gallons it slows to a creep then a drip. Im looking online for my system gpd rating.

[Squiers007]

The Gpd will vary depending on the RO membrane you use as each as a specific rating that should not be exceeded. That is why a flow restrictor is used. Another factor that can slow down a unit is the incoming water pressure. Ideally, the water pressure should be at least 40psi, but I have read other places where people recommend 45 or 50. My water pressure is really good so I run my unit at 50psi. I have a 75 gpd RO/DI unit and it makes ~4 gal/hr.

Ray, I'm curious where you bought your filters and membranes? I think you payed way more than you should have. I just replaced all 3 filters and my RO membrane on my unit and with shipping it only cost me $60. Got them from TBaquatics. Just thought you would like to know.

[RayAllen]

My Membrane cost $47.99 at lowes. Same membrane online cost the same give or take. I will check www.TBaquatics.com (http://www.TBaquatics.com) for my next change.

[RayAllen]

Is it safe to assume you can switch out a membrane with one that produces more Gpd as long as the fit is the same?

Not going to do that now, seeing I bought this one yesterday.

[Big_Pun]

you need a flush kit the membrane gets saturated and needs to be flushed, I walk out and flush mine every hour or so for min. gets it flowing again. takes me 45 mom to get 5g I also have a 100gpd membrane. yes you can switch out whatever gpd membrane that fits but as gpd goes up the more important it is to have good pressure

[RayAllen]

Thanks Chris go to know.

Mine was installed by the water softner company/plumber when we bought our home so I really have no idea what pressure is going through etc...

[Big_Pun]

Thanks Chris go to know.

Mine was installed by the water softner company/plumber when we bought our home so I really have no idea what pressure is going through etc...

pressure gauges are inexpensive and help for alot of reasons on a ro unit they can also tell you when the pre filters are bad. an the flush kit will extend the life of the ro membrane

[roscozman]

We have a 75 GPD unit from purelyh2o.com and it already had a pressure gauge installed. The recommended psi is 60-80 and we try to keep it at 70psi. It came with a flush kit and I do that once a month.

[CoryDude]

Got some pointers from Russ a few years back on something like this. Just monitor the tds output of the membrane, before it enters DI chamber. If you see that start to spike, then your membrane might be nearing the end of it's usefullness. Chlorine destroys a membrane faster than anything, so keep up with your carbon block change-out schedule.

Also, as already said, incoming water pressure makes a huge difference in lifespan and production. We had to get a pressure guage because our house pressure is too high and it damaged a couple of membranes on the ro/unit. Installed a cheapie plastic psi guage from HD (near the water heaters and well pump equipment) for $7. Added it inline right before the water enters the membrane housing. The we ordered a pressure valve from Buckeye. We use it to try and keep the pressure near 80 psi. We get about a 98% rejection rate and 5 gallons of water every 2 hrs.

You'll usually also see better production rates and tds rejections rates during the summer compared to winter months due the the incoming water temp difference.

[alton]

You have to change out the waste water restrictor, it is in your waste water tubing
Is it safe to assume you can switch out a membrane with one that produces more Gpd as long as the fit is the same?

Not going to do that now, seeing I bought this one yesterday.

[BuckeyeHydro]

A good rule of thumb is to replace your sediment filter and carbon block after six months. A more precise way to maximize the useable 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 both of the filters 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 99% of 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.

Regarding your RO membrane and DI resin, use your TDS meter to measure, record, and track the TDS (expressed in parts per million) in three places:
1. Tap water
2. After the RO but before the DI
3. After the DI.

The TDS in your tap water will likely range from about 50 ppm to upwards of 1000 parts per million (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 filter (collectively called “prefilters”) 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 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 90% (i.e., they reject 90% of the dissolved solids in feed water). So the purified water coming from your 100 gpd membrane would be about 40 ppm (a 90% reduction). Filmtec 75 gpd (and below) membranes produce less purified water (aka “permeate”), but have a higher rejection rate (96 to 98%). The life span of a RO membrane is dependant 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 total dissolved solids (TDS) in the water coming in to 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 less water as their function declines.

After the RO membrane, water will flow to your DI housing. DI resin in good condition will reduce the 40 ppm water down to 0 or 1 ppm. When the DI output starts creeping up from 0 or 1 ppm, you know that your resin needs to be replaced. Sometimes people complain that their DI resin didn't last very long. Often the culprit is a malfunctioning RO membrane sending the DI resin “dirty” 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!

Russ

[BuckeyeHydro]

We have a 75 GPD unit from purelyh2o.com and it already had a pressure gauge installed. The recommended psi is 60-80 and we try to keep it at 70psi. It came with a flush kit and I do that once a month.

Sounds like you have a booster pump? If so, you can take better advantage of that and crank your pressure up to 85 to 90 psi.

Russ

[BuckeyeHydro]

I do have another question what is the typical gallons a RO or RO/DI will make in a day if allowed to run. It takes mine forever just to make 5gallons.
Ray - the production from an RODI sytem is determined by the capacity of the membrane, which is expressed in gpd - or gallons per day. Common membrane capacities are 24 gpd, 36 gpd, 50 gpd, 75 gpd, 100 gpd, and 150 gpd.

For any given membrane, it will produce more water with 1) warmer water, and 2) higher pressure. We have a calculator on our website where you can enter your water temperature and pressure and see what your membrane should be producing under those conditions.

The most common cause for production slowing over time is clogged prefilters ("prefilters" are all the filters that treat the water before it gets to the membrane). You'll need a pressure gauge installed after the prefilters to detect this.

Russ

[twychopen]

I got mine from Bulk Reef supply. I got the "fancy" version with the tds monitor b4 and after the di. Also their replacement stuff is as cheap as I have found and very easy to replace. I love it. I highly recommend getting it. Also, I run mine around 40psi and get about 35-40 gallons in 12 hours. I make water once a week and tds reads 00.