RO/DI Help After Upgrading Membrane(s)

[Dustin1300]

I'm stuck scratching my head on my RO/DI....I have a Vertex 100 GPD unit that I wanted to beef up on to have a better product/waste ratio as well as faster. Planning to start filling my 600 gallon DT so needed something for better water production.


That all being said, decided to upgrade the unit and double up the membranes so it had two 150 GPD membranes. I followed the BRS instructions, tied the waste line of membrane #1 into input on membrane #2, both the product lines are Yd together and go straight to pressure valve that goes out product line which feeds to my two stages of DI. Also took out the in-line flow restrictor on the drain line and replaced with a 150 GPD capillary flow restrictor that I put in place on the output from membrane #2, where the previous inline flow restrictor was.


Problem I'm having is the TDS before the first stage of DI is ~60, previously with the 75 GPD membrane was getting 3-5 TDS. I ran the system for about 1 hour to break in the new membranes and sediment and carbon filters are just a few weeks old. I've replaced the stock booster pump on the Vertex Unit about 6 months ago and am getting roughly 95 PSI with the aquatech 8800 boster pump.


Any suggestions on the issue? Should the flow restrictor not be a 150, should it rather be 300? I'm just really not certain what's wrong and certain I have everything plugged in the right place.


Thanks in advance!

 

[revsgirl]

Bump


Chasing the Dream Giver, not the dream! Tonya

 

[AZDesertRat]

First off the 150 GPD membranes are not a good choice. I owned one previously and it was OK but in talking to Spectrapure they quit carrying them after just a few months. They could not get enough to pass their quality control checks so discontinued them. They tested out horrible. With over 25 years in RO that should tell you something when a big vendor refuses to carry a popular item.

It is also important to note, the Aquatec 8800 is only rated for around 100 GPD maximum and will not last long at the higher flows. its rating is actually 1 liter per minute including the waste and permeate so thats 380 GPD maxixmum, your two membranes alone are about that with no waste which is not possible.

I run a 8800 on a Spectrapure 90 GPD membrane at 95 psi and am getting 130+ GPD at 1:1 waste ratio but my system uses stored DI water to flush, backflush and pickle the membrane when not in use so I can cut the waste to that. The Vertex uses tap water to flush so the wast ratio must be kept up or you will foul your membranes in a matter of weeks or months. I have seen the Vertex in use and taken one apart and was less than impressed, in fact I am expecting to see lawsuits due to their shoddy workmanship and use or 120v AC and wire nuts rather than 12 or 24v DC and potted or sealed connections. It scared the heck out of me and looked like something someone put together out of spare parts in their garage. No thanks!

Have you measured the waste ratio to see if the 150 capillary tube is trimmed correctly? I would start there but honestly, I would remove the second membrane, replumb it back to a single then test each membrane and keep the best one in place. Your DI resin and wallet will thank you.

 

[Dustin1300]

Well, I would not say just because one vendor says they don't want to carry the product does not mean it's faulty, I've read very positive reviews. Also, opinion on the unit is not helping either, let's try to keep focus on the actual problem posed.

As far as the questions posed, I've not trimmed capillary tube and was what BRS shipped. I've always used in-line flow restrictors in the past. As far as your recommendation on throwing out $100+ of equipment I just bought to make the unit more efficient...I got recommendation from three vendors that this is a good path.

Anyone else have any constructive feedback on the problem?

 

[AZDesertRat]

The membranes are most likely part of the problem. That one vendor that tested them is one of the only vendors equipped with a lab and test facilities and the only vendor that tests all their membranes period. They have over 25 years of doing so and are number one in the industry for a reason, quality control. Call them and ask their experiences with those particular membranes if you don't want to listen to my advice after having owned one myself personally.

You asked for advice as I gave it based on experience.

What vendors gave you that uninformed information? Read the tech sheet on the Aquatec 8800 pumps on their website, the rating is 1 liter per minute which is 380 GPD maximum, waste and permeate combined. Don't get your shorts in a wad, you are getting sound advice based on many years experience both professionally and personally since water treatment has been my profession for about 38 years now as well as my hobby.

 

[Dustin1300]

I ask for advice, just not a condescending tone.

 

[Dustin1300]

Last night I played around with this quite a bit and below are some of my results, first I'll answer the questions...


- Pressure between drain of Membrane #1 and input of Membrane #2 - Steady 92-93 PSI, just a couple pounds of pressure lost from the measurement before Membrane 1 which was 95.
- Reseat membranes and check for any nicks - No nicks, and used silicone grease around the rubber gaskets. Seated as I'd expect and I've changed membranes before, not something new to me which is what's driving me NUTS!


I did several tests and changes to ensure that my lines were hooked up as expected.


Source water was 348 ppm


With Booster Pump @ 95 PSI:


Membrane # 1:
Product Water was 34 ppm
Waste water 400+ ppm


Membrane #2:
Product Water was 68 ppm
Waste water 400+


Combined the output water was 58 PPM


Without Booster Pump


Membrane # 1:
Product Water was 52 ppm
Waste water 400+ ppm


Membrane #2:
Product Water was 74 ppm
Waste water 400+ ppm


Combined was 62 ppm




I am at a loss and very frustrated. If the 150 GPD does a 98% rejection rate then it'd take the 348 ppm and drive it to about 7 ppm. (That's excluding the solids that would have been pulled out in the sediment/carbon filters)


Any other ideas or test you'd recommend?!? My baby is ready for filling!

 

[AZDesertRat]

Not very good at all. How much water has been made with the membranes, they normally improve a little with time as they saturate but thats quite a bit they would have to come up and probably not going to happen. I hope you don't take this the wrong way but those really are not a good choice of membranes based on experience, not opinion. Hate to see you spend money again but maybe you can return them as you are not satisified with them as i would not be either.
I can give you some numbers to compare to. My tap is 630 TDS, temperature averages 57 degrees F, I run a single SpectraSelect 90 GPD membrane on a Aquatec 8800 booster set at 95 psi and an getting a RO only TDS of between 2 and 3 on a handheld COM-100 TDS meter, produce 120-130 GPD and the membrane is over 5 years old. You should be getting better.

Suspended solids do not register as TDS so the sediment and carbon block filters have very little to absolutely no effect on TDS. It may drop a couple TDS due to the chlorine and volatile organics the carbon removes but its pretty insignificant in the big picture. TDS is in the 0.0001 micron range, much smaller than a sediment or carbon filters micron ranges.

Nice rock work, like the arches and caves! Fish are going to have fun exploring.

 

[Dustin1300]

Sorry about the rant yesterday, just did not read it as constructive feedback:neutral:

I'm about to send an e-mail to BRS. I'm not very happy with the results and your experience with RO/DI far exceeds mine but to be honest, I've never really had any issues with them

Even if I modified the flow restrictor, would you expect me to have much benefit on the TDS?

 

[AZDesertRat]

The suggested 4:1 waste ratio will change the RO permeate TDS, maybe not as much as you need though.
I sent you a PM with a couple more questions/suggestions to try.
One thing I forgot to ask though is are you using softened water or do you know your hadrness? Membrane manufacturers recommend softened water and most manufacturers, not necessarily vendors, will not honor a warranty claim if its not softened or soft water.

I love BRS chemicals and have two 5 gal buckets of their 2 part Mag supplement plus smaller containers of GFO, alkalinity and calcium suplements but they are not the gurus when it comes to RO. They just don't have the experience or facilities to research, test and evaluate components. There are several vendors that do and many that have better pricing on better or comparable components. Not to knock them but chemicals are their forte not water treatment.

 

[Dustin1300]

Water is softened with solar salt and I softener is only about 7 years old and I did a cleanout of the brine tank last year. It's functioning well so water is not hard. I'll get back on PM once I have a chance.

 

[AZDesertRat]

Sounds like you have done everything right? That is puzzling.

 

[Dustin1300]

That is puzzling.

This hobby is full of things like that, that's why I like it. In the 8-9 years I've been reefing I've faced plenty of "puzzling" situations!

Some other observations from last night...PSI from drain of membrane 1 to membrane 2 entrance showed 92-93 PSI. I also removed membranes and looked for any nicks in the gaskets and re-seated them to ensure the flushed water was not making past the gaskets. No dice too!

 

[cdness]

I am late to this one... I would have to agree with AZ as I have followed his advice in the past and had great success with my RODI system. I have always considered adding the "piggyback" kit but after reading and research I found it wouldn't help all that much.

Good luck with the RODI but it sounds like you are on the right track to fix any issues you have.

 

[Dustin1300]

We'll see how BRS responds to a refund on the membranes. I'm going to test them out individually tonight and if the values are still crap, definitely want a refund on something that should be producing 6-7 TDS or better at the 98% rejection rate. My 1000 gallon system would sure suck up a LOT OF DI if I'm getting 60 TDS before first stage of DI.

 

[Dustin1300]

Was just looking at the vertex 200 GPD unit and they have the lines configured differently than what BRS recommends. With the BRS configuration it would definitely have less waste water but I'm going to test each membrane separately but also go ahead and try it the way Vertex recommends.


http://www.vertexaquaristik.com/Por...yingSystems/ro-diSystems/puratekManual200.pdf

 

[Dustin1300]

I did a round of testing again last night and give up on these membranes. I'd HIGHLY recommend never buying the 150 GPD membranes from BRS. I've requested a refund as they do not meet the 98% as advertised!


I did not try the Vertex method as it kind of defeats the purpose of trying to make better use of my water and not waste as much. That being said, I tore everything apart last night, did find a kink in one of the lines so I replaced all lines and made sure no clogs existed, and then tested single membranes of 150 GPD.


- Test membrane #1 without second membrane w/ booster - 27
- Test membrane #1 without second membrane wo/ booster - 28
- Test membrane #2 without second membrane w/ booster - 24
- Test membrane #2 without second membrane wo/ booster - 26


After I combined the two and reran the two membranes got a TDS of 45 ppm with booster pump and 64 ppm without booster pump.


I give up on these 150s, stripped it down, changed flow restrictor back to the 75 GPD and got 1-2 PPM on my output TDS right after the membrane. I've got some feedback that the 150 membranes are of very low quality and all these tests prove so.

 

[AZDesertRat]

It has nothing to do with BRS and hopefully they refund your money. It is the membranes, they just are not high quality for some reason and do not have a very good track record when tested. I think every end user should test their systems from start to finsih to make sure they are actually doing what they claim to do. Most of us assume an RO/DI is plug and play and thats not the case at all. They require some research up front and some tweaking when set up and a little monitoring when in use. Not every filter, membrane, resin or flow restrictor is the same, some work, others work well and that working well is what extends the life of everything, gives you higher water qualitty and ends up saving you money over its lifespan.

Sorry you had to go through all that, it really sucks. Been there done that.

This is the normal way two membranes are plumbed together in a residential type system:

http://spectrapure.com/huds/DUAL.pdf

You will also note Spectrapure and most others do not recommend reducing the waste ratio on dual membrane systems as you are sending the concentrated brine from the first into the second and reducing the flushing effect of the waste would not provide the volume or velocity to keep the membrane operable, quickly failing if your tap TDS is normal to high.

 

[Dustin1300]

I really appreciate the help. That's exactly as I had mine configured. After I redid all the tubing, tested the membranes by themselves and had bad TDS it was clear the membranes were not functioning as I'd expect. I'm going to run to PA in a few hours and pick up two 90 GPD membranes as well as a new flow restrictor today so hopefully should be squared away after that. I'd say with the pressure I'm getting with booster I should be able to reasonably get ~200 GPD and hopefully TDS of 7-8 or less. I've read some of the techniques now on modifying the restrictor valve to get the expected waste ratio.

While it was an inconvenience the membranes did not test out well, it was at least a learning experience and BRS will be processing an RMA for the refund of the membranes. I should have good results to report this afternoon. (As long as wife does not go into labor, baby due on 4/16!)

 

[Dustin1300]

Just got back from Premium Aquatics and put the 2 X 90 GPD units in place (And 90 GPD flow restrictor) with the same configuration and getting a TDS of 2. Woohoo, now I can actually make some progress on my project again