Eating Up RO Membranes

[flyfisher2]

Hello Reefers,
I need some help. I've been eating up RO membranes for over a year. I'm on my 4th. All brand new, all Dow Filmtec. I flushed the sediment, carbon filters prior to hooking up to the RO membrane. All was working well had a rejection rate 0f 5 prior to DI. I produce about 60 gallons a week and all was good for the last three months. Last week it creeped up to 3 TDS then 7 this week. I disconnected the hose between the membrane and the DI and tested the water from the membrane. The reading is 108. Waste water shows 256. I changed the DI and I'm getting 0 TDS DI but I already know the DI will be exhausted in no time. As I said this will be the 4th Membrane since April of last year. Please tell me what can be causing this. What I'm doing wrong?

 

[flyfisher2]

I need to stop replacing these as often as the sediment filters

 

[flyfisher2]

I've been running 5 micron sediment, 5 micron carbon block, 1 micron sediment, 1 micron carbon block, DI Cation Resin Filter , DI Anion Resin Filter, and 1 DI Mixed Resin Filter

 

[KStatefan]

Is there chlorine getting thru your carbon?

Are you letting the membrane dry out between uses?

 

[flyfisher2]

I'm using two carbon blocks and both are three months old. RO in permanent install so it's always got water in the system.

 

[KStatefan]

"I disconnected the hose between the membrane and the DI and tested the water from the membrane. The reading is 108. Waste water shows 256"

How much water had you run thru before taking this reading? If is was when if first started up it could be TDS creep

 

[flyfisher2]

I thought of that as well and collected 30 gallons and tested again the same way. Same reading of 98-108

 

[Snoopy 67]

You on well water?
NO hot or warm water is being used is it?

 

[flyfisher2]

City water and connected to outside hose bib

 

[flyfisher2]

Line is not in the sun.

 

[Mike konesky]

Could be a bad membrane housing or O rings? Highly doubt it's the rings. Housings are cheap. Might be worth a try.

 

[flyfisher2]

Fair enough. Just want to find a solution. this is driving me crazy and costing me too much.

 

[flyfisher2]

If it were the housing then that would mean the membranes are technically still good as they are then just being bypassed?

 

[CMMorgan]

You on well water?
NO hot or warm water is being used is it?

What does hot or warm water do? We are in Florida - our water is always warm - hot in the summer. (Pipes are in the attic) great for showers...

 

[Woodyman]

Have you tested for chlorine/chloramines post sediment and carbon? If not just based off of what I've read so far I would start with that and diagnose based on that result.

 

[Woodyman]

What does hot or warm water do? We are in Florida - our water is always warm - hot in the summer. (Pipes are in the attic) great for showers...

Hot water degrades filters and if hot enough can actually melt the film of the RO membrane.

 

[Mike konesky]

What does hot or warm water do? We are in Florida - our water is always warm - hot in the summer. (Pipes are in the attic) great for showers...

Hot water can burn up your membrane and system. If your outside line is exposed to the sun then it may be a good idea to flush the feed line until it's tap temp.

 

[Mike konesky]

Try just reseating the membrane. Pull it out all the way then make sure you give it a firm push into place when seating.

 

[Woodyman]

Have you tested for chlorine/chloramines post sediment and carbon? If not just based off of what I've read so far I would start with that and diagnose based on that result.

If your chlorine/chloramines are high enough you could be burning through carbon quicker than your changing which is leading to the premature death of your membranes.

 

[CMMorgan]

Hot water degrades filters and if hot enough can actually melt the film of the RO membrane.

Hot water can burn up your membrane and system. If your outside line is exposed to the sun then it may be a good idea to flush the feed line until it's tap temp.

Good information. My RODI does an automatic flush but not long enough to get to cool water. I will try running a faucet in the same line prior to starting to fill the ATO reservoir. Appreciate the advise.
Sorry, OP, but I cannot think of anything else that you have not tried. Perhaps try ordering the membrane from another supplier? Is there a chance that the ones they sell you are just old? Also consider getting your water tested independently.