Replacing RO membranes

[MarkW19]

It says in the manual for my RO unit, that the membrane should be changed every 6 months, or more, depending on use. So, how can I tell when the membrane needs replacing? I use a TDS meter to check for TDS, so I guess when they go up it means it's not being as efficient...

But could my RO unit also become not be as efficient in removing chlorine/chloramines etc., which won't show up in my TDS test and therefore I wont know?

 

[fishfreek]

The TDS will climb as your membrane approaches its replacment point. The exact time frame for a replacment will depend a great deal on the amount of water your making and the quality of the water going into the filter. The dirtier the water the faster the membrane will need replaced.

The clorine and other items are usually removed/nutralized by the carbon cartrages. These do need to be replaced on a secheudle that is often more regularly than the RO membrane itself.

aquariumwaterfilters is one of our sponsors (aquafx) they have a few good articles on their site about RO filters and their maintance.
http://www.aquariumwaterfilters.com/Library/Library.html

Sure alot of their info has to do with their products but the basis of the info is valid for all RO units.

 

[MarkW19]

I think I'll be changing the carbon carts first then, I guess there's no way I can tell how much chlorine is in the water without a chlorine test kit ? I've had the RO unit for 6 months, and the water going in is 150TDS. It brings it down to 2TDS. Not sure about chlorine/chloramines because I don't have a test.

 

[MarkW19]

Should I be testing for chlorine/chloramines now, as it's been 6 months since I got the RO unit?

 

[MarkW19]

I hope not because I cant find a testing kit anywhere Or are they contained in the TDS?

 

[AquaFX]

MarkW19,

The TDS meter will not tell you the chlorine or chloramines levels. You can get a chlorine test kit at Walmart CHEAP. Ammonia can be tested to let you know if chloramine is present. Test for ammonia after you pass the tap water through the carbon. Also consider ammonia reducing carbon, it really saves your DI's.

The membrane does NOT need changing every 6 months, more like every 2 to 3 years. We use only DOW membranes, but that really should not matter. If it is a bargin unit that has some kind of membrane they will not stand behind, you will spend the money you saved very quickly on membranes. I hope this is not the case. I do not understand the every six month membrane changing instruction. Are you sure you read it right?

Marianne

 

[MarkW19]

It's not the membrane that's changed every 6 months, it's the sediment and carbon filters

 

[MarkW19]

I didn't know ammonia was present in tap water?

 

[AquaFX]

Ammonia never was in tap water (unless there was a contamination problem). It is now added! Sounds crazy, but it is used to stabilize chlorine. Chlorine can form THM's without it.

 

[seaham358]

Mark you have it right now, Membranes last 2-3 years...... The resin in the DI unit and other filters need to be changed but not the Membrane. They cost too much to change every 6 months.

 

[lando]

I was having trouble with PO4 in my RO/DI water. It was .1. I just got back from the LFS and got a new sedement prefilter, a new carbon filter and for the third stage I got a special filter that is specifically designed to remove PO4. I did not change the resin in my DI membrane and never knew this could be done. Should I still plan on replacing the resin? Will this help with PO4 issues? Thanks...Lando