How do you know when its time to replace your RO filter?
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Tristan
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Do you mean the membrane? You should replace it every year or two. If you flush it for a few minutes before producing RO/DI water then that will extend the life of the membrane. You should have a 3-way or at least a 2-way TDS meter that can measure the water that comes out of the membrane into the DI resin.
Tristan
Well-Known Member
Do you mean the membrane? You should replace it every year or two. If you flush it for a few minutes before producing RO/DI water then that will extend the life of the membrane. You should have a 3-way or at least a 2-way TDS meter that can measure the water that comes out of the membrane into the DI resin.
Greenstreet.1
5000 Club Member
I usually change them out when the amount of water flow coming out drop with my unit that usually means something is dirty.
RO membranes should last 3-5 years or longer if you keep up with your sediment and carbon replacements, use quality replacements and do an annual disinfection of the system. I'm at 8 years and my membrane is still performing same as new at over 99% rejection rate.
Generally the best indication you need a new membrane is a drop in GPD due to plugging or fouling. This will happen before you see a rise in RO only TDS which means the rejection rate is falling off. Flushing before you make water has no effect at all on the membranes lifespan, it is a feel good thing giving you a warm and fuzzy feeling. If you want to use a flush kit, use it for a couple minutes each time you shut the system off, not start it, so you flush some of the concentrated TDS away on the waste side so the membrane is not stewing in it when not in use. Still not proven to work but it is better than start up. A DI bypass valve, not a flush kit, will increase the life of your DI resin though.
Generally the best indication you need a new membrane is a drop in GPD due to plugging or fouling. This will happen before you see a rise in RO only TDS which means the rejection rate is falling off. Flushing before you make water has no effect at all on the membranes lifespan, it is a feel good thing giving you a warm and fuzzy feeling. If you want to use a flush kit, use it for a couple minutes each time you shut the system off, not start it, so you flush some of the concentrated TDS away on the waste side so the membrane is not stewing in it when not in use. Still not proven to work but it is better than start up. A DI bypass valve, not a flush kit, will increase the life of your DI resin though.
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How do you normally recommend going about the annual disinfection of the system DesertRat?
chris124
Active Member
This is year two on the membrane. I think the problem is my water company gets their water from wells and it is filthy. Thats got to be my algae problem. Because my nitrates are 0 and my po4 is 2.0 and its in my rodi water. Im going to the lfs tonight and their going to double check everything. Plus when I do my water change and give the algae a day or to it grows like wildfire.
ngvu1
Valuable Member
How can you have 2.0 ppm phosphates if the tds is 0 "zero"? Zero TDS means there is nothing else in the water but H2O right? or maybe the tds meter cannot detect phosphate....I am confused.
dbl
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I simply replace the pre-filters (carbon/sediment/2 DI's) every 6 months. I simply look at it as an $80 investment, to keep a "whole lot more than that" investment, with a clean water supply. I'm hoping to get 3+ years out of the membranes (two of them) by doing so. It makes knowing "when" to replace them rather easy.
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My first RO membrane lasted more than 10 years. The second one is still going after several years. I wont' replace it unless the flow through it declines.
The longevity of the membrane depends on the quality and maintenance of your prefilter and carbon block, if you are using soft water or not, how well you are keeping the membrane flushed via the 4:1 or whatever waste ratio and how you use your membrane, ie small frequent batches versus nice long filter runs to flush the system well.
I'm on year 8 on my present membrane with no issues at all.
I'm on year 8 on my present membrane with no issues at all.
Harold Green
Well-Known Member
Simply put add a three way valve directly after the ro membrane. Bypassing the di filters allow the ro unit to run measuring the tds of the output. Keep checking until it reaches the lowest reading(may take five to ten minutes depending on water pressure. At lowest reading divert water through the di resin. Replace any time the tds gets above 0. If the membrane tds rises and prefilters are clean then it's time to change the membrane.
srad750c
Well-Known Member
Get one of these puppies, change your carbon block and prefilter about 6-8 months, backflush 6-8 months. My last membrane lasted me for 5 years.
http://www.tdsmeter.com/products/dm1.html
Before
After
http://www.tdsmeter.com/products/dm1.html
Before
After
chris124
Active Member
I have one of those and its giving a reading of 6ppm before going through Di stage and 0ppm after. However my lfs just test my tds with two different tds meters and got 30ppm. So I have ordered a new membrane and a handheld tds meter. What could be wrong with the inline meter?Get one of these puppies, change your carbon block and prefilter about 6-8 months, backflush 6-8 months. My last membrane lasted me for 5 years.
http://www.tdsmeter.com/products/dm1.html
Before
After
srad750c
Well-Known Member
Contamination from setup, dirty electrodes or improper calibration from mfg. Here is cleaning/calibration info:
http://www.tdsmeter.com/calibration_maintenance.html
http://www.tdsmeter.com/calibration_maintenance.html
