R/O membrane life expectancy

[karlseith]

How long can I expect my 100 gpd R/O membrane to function properly before I need to replace it? I have replaced the 1 micron and carbon pre-filter 4 times so far, and the system runs pretty much 24/7.

Thanks,
Karl

 

[Atari]

It's very difficult to say how long it will last. It depends a lot on your tap water quality. The only thing you can really do is take TDS readings frequently, which most people do anyway.

 

[karlseith]

TDS is GH and KH right?

 

[fishfreek]

Usually you will see your TDS start to climb as well as your total RO output start to fall off. If you have really clean water going in to the membrane then it will last longer.

12-18months seems to be a good average livespan.

TDS stands for Total Disolved Solids. This represents basicly everything that might be in the water aside from the 2 hydrogen and 1 oxygen. Dust will affect your TDS measurement as well as any other impurity.

 

[Atari]

If you don't have a TDS meter you should definitely look into it.. they are quite inexpensive and pretty much essential when it comes to any kind of water purification equipment.

I got mine from ebay for under £20 and I'm guessing they will be even cheaper in the states.

 

[loganj]

I would agree with fishfreek that 1 yr is a good average although there are many factors that apply. One thing you can do to prolong the life of the membrane is to periodically backflush the membrane. This will remove buildup on the outer layer of the membrane. A TDS meter is really the only way to be sure though.

 

[kwan]

So what kind of TDS reading is consider to be good?

 

[fishfreek]

TDS of less than 10 would be good. A TDS less than 5 would be great and anything less than 3 would be excellent. IMHO

 

[quarryshark]

Here is a link for some reasonably priced TDS meters.
http://www.freshwatersystems.com

 

[BillyZ]

found this handheld one on ebay: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=294&item=5703139066&rd=1 $20+ after shipping isn't bad at all. I recognize the brand name, Hanna, anyone else have anything by them?

 

[Atari]

Yeah Hanna is a good brand.. I used to have a pH meter by them that mysteriously disappeared. I'll probably replace it with another Hanna when funds permit.

 

[pufferman]

with my kinetico RO filter it uses the patented Everclean rinse system which actually rinses the membrane and makes it so i dont have to replace the membrane for ten years.

 

[kwan]

I just measured the TDS in my RO water and it read 60ppm which is ok. And the SW in my main tank reads 650ppm. What TDS value should we expect in the main tank?

 

[Atari]

There's really no point in measuring the TDS in the tank.. it will more often than not be off the scale anyway.

Also, 60ppm is quite high for RO water.. my tap water is only a bit more than that. You need to retest it making sure to use a very clean cup. IMO when the readings start to climb over 20-30ppm consistently, you need to change the membrane.

 

[kwan]

Ok, my RO water might be contaminated because I used a sample from the water butt which I have been mixing SW with. I'll check it again. However, my tap water reads 440, and that is London water. And you know what London water is like.

So a high TDS in the tank is expect, right?

 

[Atari]

Hehe, you need to move to Manchester

Yep, it's normal for the TDS to be very high in the aquarium.

 

[kwan]

Yep, thats where you can make a decent cup of tea

And thanks for the info!

 

[fishfreek]

ANything in the water will affect the TDS measurement. So unless your sampling container (cup) is extremly clean you can end up with a false reading.

Having a tank with very low TDS would surly spell disaster. As this would imply low salinity and low levels of the essencal trace elements. It would also imply next to zero bactera in the water as well as next to zero suspended waste.