Stupid RO question

[altezza]

i got a ro system with a 100 GPD membrane, and my PSI was around 50. I was able to fill a 5gal deer park bottle in 2 hours with ro water. However, recently bought a booster pump and increase my psi to 80...how the system was able to fill the 5 gal bottle in 30 min. BTW my TDS is around 7.....does this sound right?

Edited September 7, 2009 by altezza

[ctenophore]

If you have a de-ionizing post filter after the RO membrane, then 7 is too high. It should read zero. But without a DI postfilter, then 7 is a pretty decent number. Not great but certainly far better than tap water.

[altezza]

yeah the water came out through the membrane and enter the DI, but the TDS is still around 7....is my membrane gone? or should i replace the resin? i just got the resin about 2 week ago.

[L8 2 RISE]

If you are running your water through both RO and DI, your TDS should be at zero. It may be that your water coming out of the unit is at zero, but there are some solids in the container, which is fine, it's just messing up your reading. I suggest getting a small container thats just big enough to fit the tds meter in, then swish ro/di water around in the container 3-4 times, then fill it with ro/di water and test. If the water still doesn't read zero, then there's a problem.

[johnnybv]

If you are running your water through both RO and DI, your TDS should be at zero. It may be that your water coming out of the unit is at zero, but there are some solids in the container, which is fine, it's just messing up your reading. I suggest getting a small container thats just big enough to fit the tds meter in, then swish ro/di water around in the container 3-4 times, then fill it with ro/di water and test. If the water still doesn't read zero, then there's a problem.

good advice on getting a true tds. Get it right out of the unit into a clean cup rinsed with the water to be tested..

john

[mling]

i got a ro system with a 100 GPD membrane, and my PSI was around 50. I was able to fill a 5gal deer park bottle in 2 hours with ro water. However, recently bought a booster pump and increase my psi to 80...how the system was able to fill the 5 gal bottle in 30 min. BTW my TDS is around 7.....does this sound right?

 

What RO system do you have ? I can only dream of getting your output rate of 5 gallons in 2 hrs, it takes my Air Water & Ice Tyhpoon 10 hrs to do that, at best with a 150 GPD membrane, and my house PSI is 90 to 100.

 

One tip I got from a fellow WAMAS was to reverse flush the membrane once in a while. I did it and the TDS from water leaving my membrane fell to under 10. This meant alot less work for the DI. Depending on your system, if you can "see" the DI rasin, it should be blue when new and turns brown when exhausted. New "blue" DI rasin has always got my 0 TDS.

[extreme_tooth_decay]

yeah the water came out through the membrane and enter the DI, but the TDS is still around 7....is my membrane gone? or should i replace the resin? i just got the resin about 2 week ago.

 

 

If your TDS is 7, your membrane is fine. You need to look at your DI to get rid of those last few TDS (although I think it is quite silly)

 

It would be interesting to know the TDS before the DI stage.

 

tim

Edited September 8, 2009 by extreme_tooth_decay

[Jon Lazar]

I can only dream of getting your output rate of 5 gallons in 2 hrs, it takes my Air Water & Ice Tyhpoon 10 hrs to do that, at best with a 150 GPD membrane, and my house PSI is 90 to 100.

 

mling,

 

Something is wrong if you're only getting 0.5 gph (12gpd). Assuming all your elements are good and everything is hooked up right, maybe you have a tube that is crimped or otherwise constricted to reduce your water flow. I would troubleshoot more.

 

Jon

[extreme_tooth_decay]

mling,

 

Something is wrong if you're only getting 0.5 gph (12gpd). Assuming all your elements are good and everything is hooked up right, maybe you have a tube that is crimped or otherwise constricted to reduce your water flow. I would troubleshoot more.

 

Jon

 

 

5 gallons in 2 hours is 2.5gph (60 GPD). That is an excellent rate.

[L8 2 RISE]

5 gallons in 2 hours is 2.5gph (60 GPD). That is an excellent rate.

 

yes, however mling gets 5 gallons in 10 hours.

[davelin315]

I would say something's not right with both of yours. Mike, I can't remember if you brought that over once or if it was someone else, but a 150gpd membrane should be producing at least 75 gpd optimal. One thing is that your water pressure is too high on the membrane, perhaps it's damaged from that and not producing what it should?

 

For the other one, it's producing too much water - 240 gallons per day is way too much. My guess is that the membrane is damaged or the restrictor is not matched up properly (which could also damage the membrane). Sounds like too much is being forced through your membrane so it's not running correctly. If your DI is fresh and it's not catching all of the crud in your water, that also suggests to me that something is not right - too many TDS in your water coming through the membrane at too fast a pace for your DI to keep up with it, hence your 7 TDS.

[altezza]

Thank you all for your advice. so producing 5gal of ro every 30 min is not right? i'll take out the membrane and reinstall it later to see if that help. my resin was blue when i bought it..after one day it turns brown. so from what you said its already exhausted therefore i need to buy more resin?

 

How long does resin last anyway?couple of weeks before it turns brown?

Edited September 9, 2009 by altezza

[Brian Ward]

Thank you all for your advice. so producing 5gal of ro every 30 min is not right? i'll take out the membrane and reinstall it later to see if that help. my resin was blue when i bought it..after one day it turns brown. so from what you said its already exhausted therefore i need to buy more resin?

 

How long does resin last anyway?couple of weeks before it turns brown?

 

If your DI resin has already changed color then:

1- yes, it's exhausted

2- your RO membrane isn't working

The DI resin should produce several hundred gallons of 0 TDS water before being exhausted (if your RO membrane is doing its job).

this could be for several reasons:

1- your prefilters aren't working so the RO membrane is clogging and unable to do its job

2- your RO membrane is damaged for some reason

 

If you have a DI bypass on your unit, or can figure some way to get RO-only water out, then get that and check the TDS. It should be around 15 but no higher than about 25 (lower is OK, just unusual depending on the quality of your source water). Also, you said you are running a booster pump to boost your pressure to 80psi - check the specs for your membrane, but usually 75psi is the max you should run, any higher can damage the membrane.

 

For reference:

I have an AWI Typhoon III unit. I run a digital dual TDS meter so I can monitor the RO-only TDS to know when to flush the RO membrane and the RO/DI TDS so I know I'm getting 0 TDS and when to change the DI resin (I highly recommend using these digital dual TDS meters for very easy and seemingly accurate monitoring of the performance of your unit). My tap water runs around 400 TDS. My RO-only water runs between 15 & 25 - any higher than 25 and I reverse flush the RO membrane and it comes back down. My RO/DI water is typically 0, but as I mentioned when it goes above 1 I change the resin. We have chloramines here in DC, so I replaced my 5 micron carbon filter with a catalytic carbon cartridge. I also run a booster pump to get 75psi and maximize my water production and the efficiency of my membrane. I have a 75gpd membrane and I can typically fill my 44-gal brute trashcan (with the position of the float valve, it probably holds about 30 gallons) overnight - about 7-8 hrs. That is about 100 gpd if you do the math. This is OK because the Dow filmtec membranes are rated for 50psi, but have a max pressure of 75psi - so at 75psi they produce more product water.

Edited September 9, 2009 by Brian Ward

[extreme_tooth_decay]

Thank you all for your advice. so producing 5gal of ro every 30 min is not right?

 

 

5 Gal per 30 minutes is good production. It sounds like your membrane is probably ok, but it would be interesting to test the TDS before the DI stage. If you get something like 7, it is working.

[mling]

I would say something's not right with both of yours. Mike, I can't remember if you brought that over once or if it was someone else, but a 150gpd membrane should be producing at least 75 gpd optimal. One thing is that your water pressure is too high on the membrane, perhaps it's damaged from that and not producing what it should?

 

For the other one, it's producing too much water - 240 gallons per day is way too much. My guess is that the membrane is damaged or the restrictor is not matched up properly (which could also damage the membrane). Sounds like too much is being forced through your membrane so it's not running correctly. If your DI is fresh and it's not catching all of the crud in your water, that also suggests to me that something is not right - too many TDS in your water coming through the membrane at too fast a pace for your DI to keep up with it, hence your 7 TDS.

 

Dave,

Finally got to the bottom of my RO slow production rate problem. When I first bought the TyphoonIII with the group buy about a year ago, I was given a bad membrane. AWI was nice enough to give me a new one at no charge. I continued to have a slow rate, ruling out the bad membrane, I started looking into other issues. Learned a lot about RODI. Turns out I was wrong to assume that I would not get 2 bad membranes in a row, especially since I've read great review about Flimtec membranes.

 

This morning, I put in an old membrane I had from 4 years ago ! It worked like a charm. This is a 50GPD and it is about 3 times faster than the 2 "new" 100 and 150 GPD. Since I now have a build in TDS, I also know the water produced is ok since the "after membrane" is 14 TDS and the DI is 0. Very surprised that this old membrane is producing 14 TDS.

 

Hope this helps anyone else with RODI flow problems -> check the membrane.