So I have a question on RODI water production. I have a five stage system from Koolermax and I got a TDS meter for it and got it installed. I was a little surprised to find my tap water was hovering around 700 TDS and my product water was bouncing around the 20's and low 30's. Would adding a 6th stage help me get it to zero, and what's a good DI resin to switch to because I think that might be most of my issue.
RODI Question
- Thread starter Matthew Frost
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Alexreefer
Coral, Coral, Coral!!!
I have a BRS 5 stage ro/di and Water is coming out at 0 tds. Either you DI chamber is exhausted or maybe just try a different company for DI resin. You can get some from brs for about 12 dollars for a color changing resin so you know when to change it. I would just try getting some new resin right now instead of buy a whole new stage to add on. best of luck 
At 700 coming in, you've got quite a challenge!
Is this the unit you have? If so; that is not a RO/DI system - that is just the RO piece of the puzzle. RO systems are generally used to produce drinking water - they reduce the TDS through filtration, but that can only do so much (the small particles involved can still get through). That's were DI comes in. The DI (deionization) acts on the electrical charges involved to eliminate even the smallest particles. Without DI, most residential water sources won't reach the 0 TDS that we're looking to produce for our reef tanks.
There's an easy solution, however - just add some DI to the mix and you should be good. You could go with a single DI chamber, but I would not suggest it. If you're going into the DI stage(s) with 20-30, you'll find that you'll go through DI resin at a fairly good clip (not horribly so, but you will go through it). The problem with this and a single chamber is that as that chamber exhausts, the output will start to climb above 0 (which defeats the purpose). DI requires contact time, so when the chamber gets to about 50% exhausted (or somewhere thereabouts; hard to know for sure), you might start to see TDS >0. As you get closer to 100% exhausted, you'll get closer to the 20-30 range you're putting into it.
This is where a dual-chamber comes in. With the dual chamber, the second DI chamber picks up where the first leaves off. When the first chamber is producing 2-3 TDS, the second chamber is easily pulling that out. And since the second chamber is dealing with so little, it exhausts far slower. The second chamber allows you to exhaust 80-90% of the first chamber's media before needing to be refilled - all while producing 0 TDS. This means you are throwing away less media over time (saving money) and have a much higher chance of consistently getting 0 TDS final output. It doesn't take long for the cost of the second chamber to pay for itself!
Is this the unit you have? If so; that is not a RO/DI system - that is just the RO piece of the puzzle. RO systems are generally used to produce drinking water - they reduce the TDS through filtration, but that can only do so much (the small particles involved can still get through). That's were DI comes in. The DI (deionization) acts on the electrical charges involved to eliminate even the smallest particles. Without DI, most residential water sources won't reach the 0 TDS that we're looking to produce for our reef tanks.
There's an easy solution, however - just add some DI to the mix and you should be good. You could go with a single DI chamber, but I would not suggest it. If you're going into the DI stage(s) with 20-30, you'll find that you'll go through DI resin at a fairly good clip (not horribly so, but you will go through it). The problem with this and a single chamber is that as that chamber exhausts, the output will start to climb above 0 (which defeats the purpose). DI requires contact time, so when the chamber gets to about 50% exhausted (or somewhere thereabouts; hard to know for sure), you might start to see TDS >0. As you get closer to 100% exhausted, you'll get closer to the 20-30 range you're putting into it.
This is where a dual-chamber comes in. With the dual chamber, the second DI chamber picks up where the first leaves off. When the first chamber is producing 2-3 TDS, the second chamber is easily pulling that out. And since the second chamber is dealing with so little, it exhausts far slower. The second chamber allows you to exhaust 80-90% of the first chamber's media before needing to be refilled - all while producing 0 TDS. This means you are throwing away less media over time (saving money) and have a much higher chance of consistently getting 0 TDS final output. It doesn't take long for the cost of the second chamber to pay for itself!
Matthew Frost
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I have the AR122 model and it has two smaller DI chambers that sit horizontally on top of the unit. I think as the resin has settled I might be getting some bypass. First thing I am going to do is pack the two chambers I have with DI resin and try to orient them so the water has to travel through them vertically to increase contact time. If that doesn't work I am going to add a 6th stage. I have an additional BRS media reactor that will serve perfectly.
Ah - gotcha. Didn't see that unit in my search (they call it a 6-stage due to the dual DI canisters).
They don't make any mention of the resin being color-changing; do you know if there is any indication of it's state? One thing you could try is to put the TDS meter in between the RO-out and first DI-in. That should tell you how effective your RO system is performing. Ideal is in the 98-99% range, but 97% isn't uncommon. If you're not getting close to that range, then the solution may be up-system of the DI...
Out of curiosity, what is the pressure of your system? The membranes that I'm finding them listing with that are rated for pressure in the 80+psi range - which is higher than the average (which is around 50-60). If your pressure is too low (or too high), then the RO membranes may not be operating at their ideal performance, putting more strain on the DI than it can handle.
I agree with the plan to orient the DI and replace it; absolutely. It's hard to tell from the photos I've seen, but they also seem a little on the smaller side? If so, a 3rd chamber could certainly help.
They don't make any mention of the resin being color-changing; do you know if there is any indication of it's state? One thing you could try is to put the TDS meter in between the RO-out and first DI-in. That should tell you how effective your RO system is performing. Ideal is in the 98-99% range, but 97% isn't uncommon. If you're not getting close to that range, then the solution may be up-system of the DI...
Out of curiosity, what is the pressure of your system? The membranes that I'm finding them listing with that are rated for pressure in the 80+psi range - which is higher than the average (which is around 50-60). If your pressure is too low (or too high), then the RO membranes may not be operating at their ideal performance, putting more strain on the DI than it can handle.
I agree with the plan to orient the DI and replace it; absolutely. It's hard to tell from the photos I've seen, but they also seem a little on the smaller side? If so, a 3rd chamber could certainly help.
