RO/DI is already out 100 gallons later?

[mitsu_matt]

Well I just got a brand new RO/DI unit from Vertex, connected it and was off and running. Two weeks later and ONLY two water changes later my TDS meter is reading 7PPM and it looks like the DI resin is almost exhausted. I only made less than 100 gallons, ***!. Has anyone else had this problem and does this seem correct?

[karsseboom]

what was the water temp that was going through the filter?

[jduck]

What is the water pressure? What is the TDS before membrane?

[mitsu_matt]

Not sure the water temp, cold but not ice cold.
My water pressure is anywhere between 30 and 50, but the RO/DI has a pump and it keeps the pressure high.
TDS before membrane is between 500 and 700.

[Jukas]

Your TDS levels probably have something to do with it, however that still seems fast to exhaust a DI resin.

Average city water is between 140-400ppm TDS. EPA lists maximum acceptable contamination levels at 500ppm.

[jduck]

That is a really high level pre membrane. Have you measured what is is coming out of membrane before di? Another way to improve is put a coil of tubing in a 5gal bucket with a heater and heat up the water before it goes into membrane

[FearTheTerps]

it very well could have exhausted it that fast with such a high TDS. Is it an in-line or vertical cartridge? Usually the vertical have a higher capacity.

Using worse case scenarios, 700ppm source, membrane reduce 95%, and using a in-line membrane with a capacity of 3400 ppm.


The membrane would reduce the TDS down to 35ppm that goes into your DI resin.
700ppm * 5% = 35 ppm

3400 ppm divided by 35ppm = 97 gallons

[bamf25]

I just ran anough water through my new ro/di to fill a 140g system. It used up about 15% of my di filter. I live in the Northeast so the water is fairly cold right now. I was even a little bit surprised that it use up that much to be honest. On average the water coming into the di has about 5 ppm for tds, but when you start the unit you will get a spike in the tds coming into the unit for the first 1 minute or so, while the ro gets reved up. I saw it hit 60ish during the first on period. So if you are doing alot of on/off use, you could use the resin up faster. By fears calculation my tds is my water supply is in the 100 to 150 range.

[JoeRonda]

That is a high source water tds. I like to put the "in" sensor before the di canister so i can see what the reading is after the ro membrane, and put the
"out" sensor in the product water hose so I can see what the reading is after the di resin. That way you can tell when your ro membrane is getting exhausted. Also you should have gotten more than 100 gal of product water because even if the ro membrane becomes exhausted, the di resin should'nt let any impurities through until it becomes exhausted.

[bamf25]

He said the unit was brand new, so the ro mebranes should have close to 3 years left on them.

[Sk8r]

Ow. You might prefilter it with a Sears inline drinking water filter to see if it can knock some of that out of the water before it gets to your ro/di. You MIGHT want to install a drinking water filter on your icemaker and house drinking water.

[JoeRonda]

He said the unit was brand new, so the ro mebranes should have close to 3 years left on them.

That depends on the amount of impurites of his source water. The ro membrane will last anywhere from 3yrs. best case senario, to 6mo. worst case senario. And at $50-$80 for a replacement membrane, I would take Sk8r's advice.

[mitsu_matt]

Yea, I have a whole house filter and a filter on each of my icemakers. As stated the RO/DI was brand new so I doubt the membrane was bad.

I do have a TDS meter on my drinking RO system in the kitchen and its reading 803 today! And the vertex RO/DI has a built in TDS meter and backwash. I really thought the DI resin would last longer and wanted to see if maybe it was a problem with something else. I guess I am up a river with out a paddle on this one!

[JoeRonda]

Does your DI Resin still look grey,green? Or is it all brown?

[karsseboom]

wow my city water on the tds in 25....

[mitsu_matt]

Does your DI Resin still look grey,green? Or is it all brown?

Top down, its 8" light brown last two inches are the original darker brown.

[ragingreefer]

Did you flush all the filters one at a time with out the next filter hooked up. I did not do this with mine when it was new and it wiped out the membrane and di pretty quick. After that costly mistake I flush each step of the filter before I hook up the next. If you check with a tds meter it should drop after each filter before going to the next step.

[travis32]

I'm surprised so many people are trying to troubleshoot this. There is nothing wrong.. My in water to my RO ranges between 750 and 950 TDS. My out ranges between 35 and 50 TDS to my RODI and my DI brings it down to 0.

I get approximately 100- 150 gallons out a single DI Resin fill. I have the vertical DI resin, and I'm not sure what temp would have to do with how long the DI resin lasts? That makes no sense to me. The temp determines the speed at which the water flows through the RO. But, should not determin the rate at which Deionization occurs. Once the water is deionized I can't see how it would be "more de ionized" because it's flowing slower. 0 ions is 0 ions.

[fatdaddy]

I'd agree with Travis. I have terrible city well water and my RO knocks it down to 7ppm which I consider excellent.

How big is your DI cartridge? If it's one of those little ones, I'd say your doing good. I'd buy one of these:

http://www.thefilterguys.biz/images/TWOSTAGEDI.jpg

I wait for one to exhaust and then refill and flip. The DI they sell usually fills up one and a little more, so I just put it in the other.

There are situations that will exhaust DI extra fast such as CO2 in the water. I think there are others. If you're still concerned, I'd google for it.

[FearTheTerps]

Temperature only effects the RO membrane. A low temp will effect the waste to product ratio of the membrane(as can pressure). Where a normal rate is about 4:1 ( 4 parts waste to 1 part product), a cold water source may a rate as high as 7:1. A high temperature source water can cause the membrane to be inefficient, lowering the reject rate. A normal reject rate is about 95%-98%, a high temp can cause the rate to drop to 90% or lower. A higher temp will also effect the lifespan of the membrane itself.


TO THE OP, I would get your water tested, I assume this is well water we are talking about. Like someone said earlier, the EPA has guidelines for what is considered to be fit for human consumption, its 450 ppm. TDS meters only test for total particles, those particles could be a combination of anything. I would get your water tested by a local water company so you can find out what is actually in your water. Some things in the water are fine to drink in high quantities, but others are not. Your RODI unit works the same way, some particles are easier for the membrane and the DI to process then certain other particles. If you find out what is in the water the water company may be able to provide you with prefilters that can take most of the bad stuff out before it goes to the RO unit.

[alanbates12]

Man do you guys GLOW at night...... My TDS before the DI is 2. That reading seems really high. Best of luck and keep us posted.

[JoeRonda]

My reading after the ro membrane is 0. And the reading after the DI resin is 0 , but sometimes it says 1.....how is it possible for the source water to be 240ppm, then the ro membrane knocks it down to zero, at which point it goes to the final deionization stage and then comes out as supposedly pure "product water" with 1ppm.....where did the 1ppm come from?

[FearTheTerps]

A reading of 2ppm after the RO is pretty good, If your source water has a TDS of 100, that would be a 98% rejection rate which is very good. If the source water has a higher TDS that means your rejections rate is even better then 98%, you cant ask for much more then that.

JoeRonda, If your reading is accurate out of your membrane then your membrane is working very very well. I would check to make sure your reading is right though. I use a in-line meter and a handheld meter to verify. I would expect your reading to be 5-10 ppm.If you are getting a higher number out of your DI, that means your DI resin is leaching particles back into your product water. Check your resin, if you have been using it for a long time it may be depleted. Sometimes water can channel through the DI resin, so if you have color changing resin you may not actually see the color change. The only true way to check your resin is to just check your output TDS, once it starts to climb its time to change your resin.

An RO membrane is just a very very small micron filter, where only pure water particles are allowed to pass through. thats why the temp and pressure effect the membrane. A higher temp allows the filter to expand(basic HS science class here, hot things expand, cold things retract) which will allow larger particles through the membrane. A low pressure will not have the force to make the small paricles of water pass through the filter.

Another problem that many people run into is the GPD rating of the membrane, A smaller number will generally mean a better rejection rate. 50GPD and 75GPD are pretty similar, with a rejection rate of 95-98%, but a 100GPD membrane can have a normal rejection rate as low as 90%. I've read that a 150GPD membrane is made somewhat different and work at the same rejection rate as a 50 and 75, but Ive never used one so I dont know first hand. Just remember, bigger isnt always better.

[PRDubois]

TDS before membrane is between 500 and 700.

That is high, are you using your pond water? my TDS comming in is only 70

[Buckeye Hydro]

You've got a bad combination of high feedwater TDS, and low pressure. You mentioned you had a pump, but I didn't see how much pressure it was providing.

Also, we need the RO water TDS.

You mentioned the DI resin is changing color at the top, not the bottom. That sounds more like a fluidized DI bed rather than an exhausted DI cartridge. If you'd like to give us a call when you are in front of the system we'd be happy to troubleshoot it with you.

Russ
513-312-2343

[mitsu_matt]

I am on my own with the water as I have well water. My TDS on my RO is 700 incoming and 50 outgoing. On my RO/DI its 7 outgoing (no way to measure after the membrane on the Vertex unit as its all packaged together with the TDS meter, microprocessor and back-flush thingy). Here is the unit: http://www.aquacave.com/vertex-puratek-100-gpdbr-rodi-unit-2531.html

After reading more about this unit, maybe I should change to a 75gpd membrane and add a second DI chamber.

[MelloW33]

I'd either find a way to run the water back through the system or just get one of those 2 canister DI add-on systems.

[alanbates12]

I think Id take BuckeyeFS up on his offer to trouble shoot your unit...

[The Velvet Sea]

You're getting a 92.86% rejection rate from your membrane. 100 gpd membranes like yours will chew through DI resin when your tap TDS is high. Getting a 75gpd membrane with a 98% rejection rate or better will be a HUGE help for your problem. In your situation, with a 98% rejection rate, you will be sending approximately 14 tds water to your DI instead of 50 tds and your DI will last over 3 times as long (estimated).

[mitsu_matt]

You're getting a 92.86% rejection rate from your membrane. 100 gpd membranes like yours will chew through DI resin when your tap TDS is high. Getting a 75gpd membrane with a 98% rejection rate or better will be a HUGE help for your problem. In your situation, with a 98% rejection rate, you will be sending approximately 14 tds water to your DI instead of 50 tds and your DI will last over 3 times as long (estimated).

Now thats info i like to hear! Guess i need to do some field testing now.

[bamf25]

BUlk Reef Supply sells universal RO filters that are 75 gpd and 98% rejection and they are well priced.