Help Troubleshooting a new RO/DI system

[the buszkock]

I am having a bit of trouble. I have a Kent Marine Maxxima 35gpd RO/DI unit. It has been set up for about a week. Connected to the unit is a Premier Watts Zero-Waste Pump. I have tee'd off the tubing after the RO membrane so that I can turn two John Guest valves to redirect the flow and get RO water for drinking. Also in-line is an HM Dual TDS meter, which measures TDS after taking water from the RO only as well as the RO/DI end. There are two pressure valves connected to the unit as well. One that measures incoming line pressure, and another that measures the pressure going into the RO membrane. I will post a photo later.

Pressure is 58 psi going into the unit, about 56 going into the RO membrane. (the needle vibrates with the pump so it's hard to get an exact reading)

The TDS after the RO membrane reads sometimes as high as 44 ppm, although my tap water is never higher than 78ppm. A typical reading is between 24-34 ppm after the water has passed through the RO membrane. Once in a while the TDS dips as low as 7 ppm, which I would be fine with if it were consistent, but it's' not. However, the water always reads 0 ppm after the DI filter. These values have all been verified with a handheld TDS meter.


What could be happening?

 

[the buszkock]

 

[the buszkock]

Close thread. Problem resolved. My rec. to anyone using this unit is to carefully remove, retape, and securely fasten all JACO fittings. I had done this after a leak earlier, but had forgotten to retape a fitting on the back of the unit. Luckily it started leaking late today and revealed where air was leaking in and fouling the process. Now TDS measure 5-9 ppm, which is fine.

 

[the buszkock]

Ughh o.k. so I spoke too soon. This morning the TDS had creeped back up to 32 ppm. I fluched the membrane for about 10 minutes yesterday, so perhaps that was what accounted for the temporary improvement.

I am going to reseat the membrane today and check for any other mechanical problems. I will also remove the Zero Waste Unit and run the RO/DI system without it to see if that helps anything. I'm so frustrated but I know it's probably something simple.

Are there obvious signs of damage that I can look for when I reseat the membrane later today? If some kind of backpressure ruptured the membrane is that something I would be able to see? When the membrane is fouled is there any visible evidence? Ideas pleaseeeeeeeeeee.

Mike

 

[the buszkock]

Well, I reconfigured the system without the zero waste unit. I made sure the membrane was seated fully. All the O rings looked good-- flexible and snug in their proper places. The membrane is pushed all the way into the housing. I double checked all the lines, tightened the fittings, removed any extraneous gauges I had added. The flow restrictor is in the proper position.

The TDS level is even higher now. In fact, the TDS level is higher coming out of the RO membrane than it is going into the unit.

At what point is it safe to say the membrane has been damaged somehow?

Please anyone, advice????????????????

 

[the buszkock]

At this point it's almost funny that I'm keeping this thread open since no one ever comments. In any case I hope it will become useful to someone at a later time.

I spoke to Russ from BuckeyeFieldSupply.com and he helped me confirm the likely cause of the problem: a bad membrane. I found this on another forum too...

Re: Kent Marine Maxxima Deluxe Question

my father in law had this unit and had lots of trouble with the membranes from Kent. he ended up going with a filmtec and has had no trouble after

Perhaps then I'm not the only one. I have sufficient pressure entering the membrance (56-58 psi) have all the connections triple checked, have the membrane seated properly, all o rings checked, I run the unit for a while before testing the water carefully-- triple rinsed clear plastic cup with hand held TDS- HM3. The samples are double checked with the inline (less accurate) meters to confirm the presence of dissolved solids. It seems like I've eliminated all possible mechanical variables, so I'm left to believe the membrane is the problem.

I have ordered a new membrane and flow restrictor (might as well upgrade to 75 gpd right??) Once they come in I'll test the system and keep my fingers crossed while I do.

While I'm waiting though, if anyone has had similar problems with an RO/DI unit please share your experiences. There is definitely a learning curve for this type of equiptment and I want to know as much as I can. Thanks to the 36 people who have read this thread, but please comment. Even a word of encouragement would be nice. lol. PeAcE!

Mike
​

 

[prober]

I don't know a whole lot about these systems but I have heard of similar problems when the membrane is bad. Did you order one from a different company or do you have to stay with Kent marine for the replacement?

Hope it solves your problem.

 

[epond83]

Sorry I didn't see this earlier, I would have suggested a new membrane. How old was it? I belive if they dry out after being used they go bad rather fast. The pump should give you better esults because RO has a optimum pressure which is around 60 or 65 psi, also tempature can affect it but not a lot you can do about that.

 

[the buszkock]

I don't know a whole lot about these systems but I have heard of similar problems when the membrane is bad. Did you order one from a different company or do you have to stay with Kent marine for the replacement?

Hope it solves your problem.

I am trying a new company's membrane. I'm not even sure what membrane brand was in there because Kent relabeled it with their name on it. Kent doesn't manufacture membranes though, so who knows what it was.

I ordered a 75 gpd membrane by Filmtec. I heard good things about this company. That membrane plus the corresponding flow restrictor cost $44. It is annoying to have this problem but at least I'll be upgrading the capacity of the unit if it solves the problem.

Sorry I didn't see this earlier, I would have suggested a new membrane. How old was it? I belive if they dry out after being used they go bad rather fast. The pump should give you better esults because RO has a optimum pressure which is around 60 or 65 psi, also tempature can affect it but not a lot you can do about that.

The confusing part is that this was a brand new membrane that was only about two weeks old. I ran out at least 100 gallons of purified water so it was definitely fully saturated.

Thanks guys for posting today! I'll let you know how it works out when I replace the membrane. It should be here by the end of the week. In the meantime I have plenty else to do on my 155 bow front RBP tank.

 

[epond83]

I don't have any exsperince with RO but i've read up on them alot, i think chlorine is not good for the membrane which is why they have charlcoal filters. Also ammonia is bad for them which can be produced from chloramine going through a regular carbon filter.