How often should I be replacing the RO membrane. I change 15 gallons every two weeks and top off about 7 gallons per week. Therefore I am not making a large amount a water. BRS says every three years, just curious what others think
ro membrane (1 Viewer)
- Thread starter cheppi
- Start date
I believe they have a video and it goes into more detail, but what i recall is about 6000 gallons. Double check the video for the actual amount
reeffamily
Senior Member
go to this link. it's where to buy and learn. scroll all the way down to read
http://www.ebay.com/itm/75GPD-FILMTEC-MEMBRANE-REVERSE-OSMOSIS-TW30-1812-75-RO-/170681082848
copy and paste
http://www.ebay.com/itm/75GPD-FILMTEC-MEMBRANE-REVERSE-OSMOSIS-TW30-1812-75-RO-/170681082848
copy and paste
This is great advice. The only thing I would add is that depending on your water quality (if it's really, really heavy with solids) it may never get quite as low as you want, just something to keep in mind so you don't spend money on filters you don't yet need to change. Hopefully you know what your TDS was when your unit was new out of the box.
Like others say there is no real rule. The better maintenance you do with your pre-filters the longer it will last. For example, more stuff that gets by the sediment will eventually start clogging your membrane, so be more proactive with replacing your sediment. If carbon is run too long and chlorine gets past it will start to eat your membrane so again stay on top of your carbon changes. If you do these things you can easily get 4+ years and likely even longer at your usage. Just monitor the output from your membrane TDS and watch for it to get higher.
This may help (from our FAQ's)
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 99% 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 90% (i.e., they reject 90% of the dissolved solids in the 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 purified water (a.k.a. “permeate”) more slowly, but have a higher rejection rate (96 to 98%). 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 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
AaronBliss
Senior Member
Filmtec membranes can last much longer than a few years
Sent from my SGH-T889 using Tapatalk
Sent from my SGH-T889 using Tapatalk
Can't do a commercial post so can't refer you to a place to buy the food grade silicone grease. Be happy to email you instructions re sanitizing your system.
Russ
Russ