My DI Resin is spent already?

[Mrramsey]

Ok maybe I am missing something here but I have a new BRS 5 stage 150gpd watersaver RO/DI unit. I have only processed ~100g through it, all into storage containers. I flush the membranes before production. The TDS out of the DI is now 2ppm and the resin is all a golden color. The TDS into the RO from the tap is ~320ppm and out of the membrane ~11ppm.

I am having a hard time justifying a 150gpd unit with DI that only lasts for 100g. what am I missing here??

[shifty51008]

something isn't right, you should be getting 3ppm or less after the membrane.

whats your water pressure?

[Mrramsey]

Originally Posted by shifty51008

whats your water pressure?

97 PSI.. I know its high. I am having that fixed next week. I have the valve just cracked open enough to keep it at 60 psi when filling. oh and the water temp is low still as well at about 58 F. So there is expected to be some efficiency lost there.

[shifty51008]

well you have good water pressure. make sure the membranes are pushed i all the way, they can be tight and people think they are all the way in but there not.

also if you can check to see how much waste water you get for 1 cup of good water that will help.

are you on city water or well water?

[Mrramsey]

I am on city water.

[ganjero]

Originally Posted by shifty51008

something isn't right, you should be getting 3ppm or less after the membrane.

whats your water pressure?

I think 320 to 11 is correct. Where are you coming up with 3 or less? The membrane sold by BRS with that system is rated at 98% rejection, if you are using a water softener and the water temp is 77 degrees. If you do not meet that criteria is goes down a little which in this case, 320 to 11, is translating to ~96.5% - Seems right to me

Did you fill the DI resin cartridge yourself? Did you pack the resin extremely tight in there?

[Mrramsey]

No it was the prefilled container from BRS that was already installed in the unit.

I agree that the 11ppm is probably about right. The DI is what seems off to me.

[ganjero]

IMO it could be the resin wasn't packed tightly or it was too old (small chances of being too old though). From their website "The resin should be packed very tightly. When squeezed, there should be almost no flex to the cartridge."

I would contact BRS, they can probably help you and send you new resin. A 100g at 11ppm shouldn't deplete the resin unless your water is extremely rich in CO2 (usually well water not city water).

[shifty51008]

I have about 350 ppm Tap water and I get between 3-4 ppm after RO using a 75 gpd membrane, thats just how I figured it.

[michaellee64]

Nothing wrong with running with running your RO system at 100 psi...I've been running mine for years at that. Optimum pressure is 80 to 100 psi. The most common culprit of premature di resin depletion is high CO2 in your supply water. Spectrapure has a CO2 test kit and also some information on their site regarding this subject. I used to get approximately 80 gallons out of my di resin before I needed to replace it. I am now using a CO2 degassing tank before I pump it through my resin, and have managed to get approximately 1200 gallons and am still at 0 tds. My di setup consists of a Maxcap, Strong Based Anion Resin, Mixed Bed Resin in that order. The reason I'm running the Strong Based Resin is because I have a high silica level in my water. The Maxcap was just replaced at 1100 gallons. Give Spectrapure a call... They are awesome people to work with and will get you pointed in the right direction.

[michaellee64]

Just checked my records and I just hit 1500 gallons with only replacing the maxcap. I'll probably change out the others this weekend. My incoming water is at 660 tds and 9 tds after the membrane. FWIW... I forgot to turn on my booster pump and at 52 psi I was getting 660/17 tds which equates to 97% rejection vs 100 psi 660/9 tds at 99% rejection!

[azjohnny]

You might have a lot of CO2 in the water, CO2 will eat up DI.

If the fittings can handle the pressure leave it at the 97psi( more the better)

[Mrramsey]

How do you check for co2 in the water?

97 is still too high for the rest of the household systems, I cant tell you the number of toilet valves I have installed in the past 3 years... not to mention it is hard on the dishwasher and icemaker. I will lower it to 65-75psi.

[michaellee64]

Get a CO2 test kit from Spectrapure

[Mrramsey]

Also just posting the following:

PH at the tap is 7.4
phosphates at the tap are 0
ammonia at the tap is 0
nitrates at the tap are 0

[Sinekal]

Buying a better prefilter may help as well. My water runs about 400 ppm, after ro was still hitting 8 ppm. The better prefilter took that down to 5.

Either way your resin should not have run out that fast.

[Mrramsey]

My prefilter is 5 microns but I think I might try a 1 micron prefilter.

[aquaman67]

If you want to save DI resin, get a better (more efficient) RO membrane.The numbers are correct.

320 - 11 = 309

309 / 320 = .965

.965 X 100 = 96.5 % efficient.

If you had a 98% efficient membrane you'd be getting 6 TDS into the DI, less than half as much.

You could actually put tap water into DI and you'd get zero TDS out...for a while anyway.

The RO membrane is a mechanical filter. The less TDS you put into the DI, the longer it will last.

[Mrramsey]

The membranes are 98% efficient. The water temperature is 58 degrees so efficiency is lost. I may try running an additional coil of ro tubing into a bucket of water with a small heater to raise the water temp before it goes into the membranes.

[tkeracer619]

Cutting TDS in half doubles DI life.

You have a 96% membrane. There is no need for a 150gpd setup for a 120g display.

You will save money in the long run by replacing the membrane with a tested 98%+ membrane.

Originally Posted by Mrramsey

The membranes are 98% efficient. The water temperature is 58 degrees so efficiency is lost. I may try running an additional coil of ro tubing into a bucket of water with a small heater to raise the water temp before it goes into the membranes.

AFAIK BRS does not sell a membrane rated at 98%. They are 96%+. They can be higher.

With that pressure that temp isn't an issue. I have 2 of the same membranes you are using. I keep them in the fridge on standby in case I need to make a lot of water(300gpd).

[Mrramsey]

BRS states 98% rejection on the Dow filmtec 75gpd membranes. The unit I have uses 2 of those. I will contact BRS to confirm that though. I went with the 150gpd for 2 reasons. 50% less waste water and I have limited storage space for RO so wanted to make sure I had capacity to make some in a short period of time. Oh and I also have a second 80g that will be set up soon as well.

[tkeracer619]

Filmtech 75gpd rejection rate is minimum 96% (a filmtech spec not BRS). Often is around the 98%. My current one is greater then 99%.

Its by far the best membrane to use for the hobby. Drop one of them and go to a 75gpd. That will help. Less waste = higher tds.

[Mrramsey]

I stand corrected. I finally found a spec sheet on the filmtec membrane.


Kind of chaps my arse but oh well we live and learn. What membrane are you using? Are they all the same physical size for the housings?

[tkeracer619]

You have the right membranes, I use the same one you are.

Personally I would figure out which membrane has the better rejection. Pull the other one, triple freezer bag it, and toss it in the fridge for safe keeping. In an emergency you can add it if you need it.

Adjust the RO to waste ratio to 4:1.

Flush the membrane before and after each use. You can do this with a solenoid and controller or by hand by adding a tee before the flow restricter and adding another drain. Opening that ball valve for 30 seconds before you start to produce water will drop the tds rapidly providing you with the cleanest water from the start. Flushing after use will help preserve the membrane. RO membranes take a bit to get to running TDS.

How exactly do you have this system setup? How much and how often are you making water?

The housing is universal and many different membranes/prefilters will work.

If you don't have one you need to order a chlorine test kit to test your waste water. I learned the hard way.

[Mrramsey]

The unit is set up just as it came from BRS. It does have the flush valve that I do use before producing any ro water. I just filled the tank so my need now was certainly greater than the demand in the future. Once I start regular PWC's I am looking at 20gpw along with 7gpw for top off.