RO problem- see page two for a 5/07/07 update

[Anonymous]

I have an RO/DI unit that I have had for a few years.

I changed out all of the filters including the membrane back in April.

I changed the sediment, carbon and DI again in July.

I changed out the sediment filter last week.

Today, I noticed my pressure gauge showed a reading of zero. Hmm. Strange, but after a bit of trouble shooting I realize that the carbon filter is completely clogged. So I replace it. Now the PSI is at 70. The unit starts to produce water and I set a timer for 10 minutes to flush the new carbon filter. Ten minutes latter I check the TDS of the water and it is 98PPM. I check the tap water and it is around 160. WTF. Is my membrane bad again?

FWIW, the RO/DI is used only for refilling my 120 water change vessel. I have done a total of (6) 120G WC's since April. The only other use this unit gets is a little bit of drinking water. I have one of those 4G tanks that is filled ahead of the DI. I doubt if we use more than a gallon or two per week.

Any ideas? I checked the TDS of this unit after my last WC and the TDS reading was 2PPM. That was before it refilled the 120G tank.

Louey

 

[bleedingthought]

Russ from Buckeye has been posting here on RDO and I'm sure he could help you out with this!

Here's his bio if you want to shoot him a PM: http://www.reefs.org/phpBB2/profile.php ... le&u=32982

Good luck, Randy!

 

[Anonymous]

I noticed that Russ have been posting lately. I'll PM him if he doesn't see this thread within a day or two.

I buy all my supplies from Buckeye.

Louey

 

[fungia]

ime if you shut down the ro it takes a few days to get low tds readings again. i dont know the science of it but i would check your readings again today and tomorrow, it should go down.

 

[Anonymous]

Yup, it is more efficient to run RO continuously due to this problem, often associated with mineral creep or membrane creep or something along that line.

It is due to the embedding of ion/molecule that got push thru everytime a RO is restarted.

It is more of an issue with automatic RO topoff that often can turn on/off for dozen of time a day, and oftentimes, a device is used to limit this on/off cycle that is detriment to the water quality.

 

[Anonymous]

I accidentally let it run overnight. Now the TDS reading is down to 42PPM.

I wonder if I should let it run for another day or two. I hate wasting water....

Louey

 

[Anonymous]

I don't feel that is the right way to get the TDS to be lower (by running it constantly like that).

Is the TDS reading for the RO-only section, or it is after the DI?

 

[Anonymous]

Before the DI.

I don't think it is the right way either, but I accidentally left it running all night and the TDS was cut in half. It's weird. Now I wonder if I ran it overnight again would the TDS get lowered again.

Louey

 

[Anonymous]

After a certain number of hours, it just levels off as the TDS reach equilibrium. 42 ppm seem a bit high. What is your water temperature, and do you have a proper flow restrictor to match the RO membrane?

 

[Anonymous]

The water temperature is around 75 degrees. And yes, I have the proper flow restrictor.

Remember, this RO worked fine for years.

Louey

 

[Buckeye Field Supply]

OK - let me see if I've got this straight.

*Tap water TDS 160
*Post RO TDS is 42 (this give you a 74% rejection rate - that's really bad especially given you nearly have factory spec temperature and more than factory spec pressure)
*Post DI is ?

You're changing prefilters every three months, and even with that you completely clogged a carbon block in 3 months.

With clean prefilters you have 70 psi @ 75 degrees F

You produced about 6 x 120 = 740 gallons of permeate and about 3000 gallons of waste since your last filter change.

If we brainstorm on this some:
1. What are the micron ratings of the sediment filter and the carbon block?
2. What is the capacity in gpd of your membrane?
3. Are you taking your TDS readings with a calibrated meter?
4. Are you taking your TDS readings in a squeeky clean glass container?
5. Are you sampling your cleanest water first and your dirtier water second if you use the same container the take saples for the TDS meter?
Do you see any discoloration of the prefilters? Brown? Red?

You've obviously got some very significant sediment loading. Anything going on dowwn the street from you? New water pipes? Any major construction?

Russ @ BFS

 

[SnowManSnow]

Just ordered a new RO membrane from Buckeye

Hope you get it strait LOU!

B

 

[Anonymous]

Russ wrote:

1. What are the micron ratings of the sediment filter and the carbon block?

One micron sediment. The carbon block is The Chlorine Guzzler from Buckeye.

2. What is the capacity in gpd of your membrane?

75 GPD

3. Are you taking your TDS readings with a calibrated meter?

Yes.

4. Are you taking your TDS readings in a squeeky clean glass container?

Yes. Same glass that I have been using for years. It is rinsed before and after every use.

5. Are you sampling your cleanest water first and your dirtier water second if you use the same container the take saples for the TDS meter?

I have never really paid attention to the order I test in. I usually rinse the glass with the water that I am about to test first.

Do you see any discoloration of the prefilters? Brown? Red?

Filters turn a yellowish color. I try to change the sediment filter before they turn very yellow so as to pro-long the life of the other filters.

Anything going on dowwn the street from you? New water pipes? Any major construction?

Not that I am aware of, but it makes since to me that something must have happened that caused this sudden clogging.

Louey

 

[Anonymous]

Snowman wrote:

Just ordered a new RO membrane from Buckeye

That's probably what I'll have to do. It just sucks because I just replaced it in April. I thought membranes were supposed to last for years, not months.

Louey

 

[SnowManSnow]

I replace mine every 6mos or so... if i can remember

 

[Buckeye Field Supply]

Your prefilters loading up in such a short period means you have a high sediment load.

Have you pulled your membrane out of the housing to inspect it? You could have biofouling or something unrelated to the sediment.

Do you have a high silicate load?

If you've run your system for years w/o problems this makes me think you're experiencing a temporary problem due to waterline construction, etc.

Russ

 

[Anonymous]

Russ wrote:

Have you pulled your membrane out of the housing to inspect it? You could have biofouling or something unrelated to the sediment.

No, I haven't inspected it. I'll do that.

Do you have a high silicate load?

I don't know.

If you've run your system for years w/o problems this makes me think you're experiencing a temporary problem due to waterline construction, etc.

It does sound that way. Except for one thing. I have a second RO/DI that is dedicated to make-up water. It is working fine.

Oh well, doesn't sound like there is anything I can do to fix it. I'll order a new membrane. I usually keep an extra membrane on hand for occassions such as this. Maybe I'll order two.

Louey

 

[Buckeye Field Supply]

So if the clogging is specific to this one system in your house, that makes me think biofouling.

Have you noticed a bad odor when you change your prefilters? Smell the ends of the membrane when you pull it our as well.

Russ @ BFS

 

[Anonymous]

No, I haven't noticed any strange smells.

The only thing that was out of the ordinary is that I changed the DI filter on the OTHER RO/DI last Thurday night and left for 3 days. When I came home on Sunday the laundry room was flooded because I didn't tighten the DI housing completely. What a mess. I don't think that this should have any effect whatesoever on this particular RO/DI unit.

Louey

 

[Buckeye Field Supply]

So how did this stuation end up? Did you get everything swuared away?

Russ