RO membrane fried in 8 months

[amcvay1979]

My water setup is kind of unique and I thought I was doing a good thing, I'm thinking my plan is costing me money. From my water main I have a whirlpool whole home regenerating filter, basically it removes chlorine and I'm assuming it's an ion exchange type of filter and I can set it to regenerate every 1 to 12 days. From there I have a whirlpool softener and then my RO unit.

So I noticed my TDS in to my RO was 150. My tds out of the membrane was 30. This didn't seem right so I just installed a new membrane and it's down to 4 now, great.

So I'm wondering if what I've been told is true that a softener can kill a membrane or if my original membrane was just cheap and junked out?

Anyone else have a softener before an RO and not experience membrane life shortage?

[DDon]

I have used a softener for 2 years or so and it didn't seem to affect membrane life.

[EricGRIT]

Disclaimer: I honestly have no idea if this is true or not.

When I put in my water softener about 1.5 years ago I read that the softener would actually prolong the life of the membrane. Reason being that the softener would replace smaller particles (hard water) with larger particles which would simply pass by the RO membrane rather than stick in the membrane. From what I've seen, that could be plausible. I definitely haven't seen any evidence of shorter RO membrane lifespan.

[amcvay1979]

I'll keep it as is and monitor it. For what it's worth my new membrane is a Dow and is one of the best on the market. For 25 bucks it's worth an experiment to see if the softener hurts or helps for a few months.

[CStrickland]

A softener is good for the rodi.
Keeping your sediment filter and carbon in top shape will help the membrane, and you need enough pressure coming into it.
Also rinsing the new sediment filter and carbon block, and sterilizing the unit when you change them out.

[dkeller_nc]

As others noted, a brine-regenerated water softener will improve RO membrane performance and lifetime.

However, I've never actually heard of a regenerable chlorine-removing filter. Typically, chlorine/chloramine is removed with carbon filtration, and there's no way for a homeowner (or a homeowner's system) to regenerate activated carbon. It'd be well worth getting some chlorine/chloramine test strips and testing the water coming into your RODI setup (but after the whirlpool fiters/softeners).

[shifty51008]

What is your waste to good water ratio? If it isnt 4:1 that will shorten the life. But a water softener should increase the life

[amcvay1979]

The old membrane was a pentair 100 and my new membrane is a Dow filmtec 75 gpd. I'll have to get a new restricter for the flow difference. My good to bad ratio after replacement was 3 good to 5+ bad in 1 hour. Properly sized flow restricter should help.

My whirlpool whole house filter is model # WHELJ1

[shifty51008]

Yeah haveing 5:3 is whats killing the membrane, you need the 4:1 to keep the membrane flushed.

[amcvay1979]

Is that a problem with the restrictor? I ordered a new 75 gpd so hopefully that'll solve it

[dkeller_nc]

Did a little research. It turns out that the whirlpool filter you mention is simply a sediment filter with an auto-back washer and about 10 lb. of carbon. The "regeneration" is the back-washing of sediment, not regeneration of the unit's chlorine removal capacity.

So depending on how long you've had it or it's been in service, it's fairly likely the unit's chlorine removal capacity has been exhausted. If you're not running carbon blocks on your RODI unit, then it's probable that your RO membrane was destroyed by exposure to chlorine/chloramine.

[shifty51008]

Originally Posted by amcvay1979

Is that a problem with the restrictor? I ordered a new 75 gpd so hopefully that'll solve it

Yes the flow restrictor is the issue, putting in the proper one will get you to the 4:1 and will make your membrane last longer.

[amcvay1979]

I run a sediment and 2 carbon blocks. The whole house filter is just for drinking water. It's been in service about a year and I still test zero on Chlorine test strips from my tap water.

[amcvay1979]

I just read more about the Whirlpool filter and it claims to have enough carbon capacity for 500,000+ gallons, or about 4 years of continuous use. I know my muni water supply is pretty good as is, I just don't like the chlorine taste and if the filter removes chlorine and any chloromines it's all the better for the RO unit.

[Buckeye Hydro]

That WHELJ1 unit is what we consider a low end, low capacity backwashing carbon tank. It is a tried and true way to remove chlorine that has been shrunk so it's not intimidating to DIYers, and then they wrapped it in a plastic case to make it look different.

Maximum service flow is 6 gpm - too low for most residential whole house applications. It claims an 82% chlorine removal in typical applications. Like any carbon tank, it will remove some sediment.

Regarding your water softener - just like hard water will leave scale deposits on your faucets and other plumbing fixtures, that scale will build up inside an RO membrane and will "plug" the membrane. The more expensive replacement membranes are (think commercial systems where they runs hundreds of dollars), and the harder the feedwater, the more necessary softening is as a pretreatment for RO and RODI systems.

Russ

[amcvay1979]

I can't say for certain the incoming levels of chlorine prior to my whole house filter, but I using test strips, I've tested zero chlorine 3 times over the past year after the filter, so my muni either uses very little, or the Whirlpool filter does a good enough job to get to read zero on a test strip which SHOULD help my carbon blocks on my RO/DI unit last a bit longer.

As for hardness, it was just slightly hard at 8 to 10 grains depending on the season. The water supply is lake fed and while we could easily live with slightly hard water, we were beginning to get stains on our brand new fixtures so I just screw it and bought it for further protection of the water lines, fixtures and my RO unit.

Seems my membrane was killed by a bad flow restrictor. Installed a new membrane and restrictor and now I'm getting zero tds after the membrane. I'll continue to keep an eye on it, output is 4:1 bad/good now so I think I solved the issue.

[Buckeye Hydro]

Just for info:

Water hardness is broken down into categories, with the hardest category starting at 10.5 grains+ per gallon.

Russ

[amcvay1979]

Just thought I would resurrect this thread. Installed new filmtec 75 gpd membrane on 12/12/15 and reading was 2 TDS. Today, 2/3/16 the tds after the membrane is now over 20 TDS. I wouldn't think this would indicate need for new pre-filters as they aren't that old, maybe 4 months tops. Would this seem to indicate that I shouldn't run my RO water after my softener?

[Buckeye Hydro]

No - I wouldn't draw that conclusion.

Seems like half the time when we have customer support calls regarding TDS readings, it ends up the readings are in error. There are a number of things that can cause inaccurate readings.

So I'd need to know more about how the readings were taken.

Russ

[amcvay1979]

I have an inline tds meter installed after the membrane, I let it run about 2 min and got that reading. Does that help?

[Buckeye Hydro]

It does - that should be a pretty decent reading.

Some things to think about:
Are you missing one of the rubber gaskets on either end of your carbon block?
Do you have what looks like a faint black line running radially around the white filter cloth on your carbon block?
Is your membrane fully seated?
Do you have an internal crack in your RO membrane housing - in the sidewall of the cup into which the membrane seats?

What you're seeing in not caused by feeding softened water to the RO.

Russ

[amcvay1979]

I'll have to tear my system apart and look. I'll do that ASAP. Thanks for the help.

[amcvay1979]

No cracks in housing, membrane was seated fully, both carbon blocks had o-rings but they all had a slimy greenish gunk on them so I cleaned them and reinstalled. Maybe a faint line around my middle carbon block but not immediately apartment.

My pressure at the membrane is 57-58 psi, and I've ran the RO for about 10 min straight and tds started at 20 and is now falling, currently at 9

[Buckeye Hydro]

and what is your feedwater tds?

[Buckeye Hydro]

IS the RO system in bright light?