How far to chase RO water for a high-end SPS tank.

[Reefer1978]

You are suggesting that a water softener added before the RO/DI reduced the TDS coming out of the membrane (before DI) ,without any change or maintenance on the membrane itself?

That's not what I would expect. Softened water should get through an RO membrane a little bit better, but it also preserves mambrane life by reducing calcium carbonate precipitation onto and into it.

@Randy Holmes-Farley that's exactly what I did... nothing was done to the RO... if anything we just kept on using it for drinking water for the last month while awaiting Softener installation. It was installed on Friday, I started making RODI water yesterday morning.

 

[Randy Holmes-Farley]

@Randy Holmes-Farley that's exactly what I did... nothing was done to the RO... if anything we just kept on using it for drinking water for the last month while awaiting Softener installation. It was installed on Friday, I started making RODI water yesterday morning.

Well, I'd just move forward and be happy, but I would be wary of advising folks on the cause and effect.

Softeners don't actually remove ions, they just swap out magnesium and calcium for added sodium. Since sodium can actually get through most membranes a little bit easier than the other two, there should not be a bigger TDS drop across the membrane due to the softener addition.

 

[Reefer1978]

Well, I'd just move forward and be happy, but I would be wary of advising folks on the cause and effect.

Softeners don't actually remove ions, they just swap out magnesium and calcium for added sodium. Since sodium can actually get through most membranes a little bit easier than the other two, there should not be a bigger TDS drop across the membrane due to the softener addition.

@Randy Holmes-Farley I seldom ever advise folks what to do, or not do, I only share my experiences.

 

[Troylee]

Well, I'd just move forward and be happy, but I would be wary of advising folks on the cause and effect.

Softeners don't actually remove ions, they just swap out magnesium and calcium for added sodium. Since sodium can actually get through most membranes a little bit easier than the other two, there should not be a bigger TDS drop across the membrane due to the softener addition.

What effect does that have coming out of the membrane on di resin? Would it last longer with more sodium vs mag and cal? Granted it was “let’s say 5” coming out of the membrane hard or soft water to begin with..

 

[Randy Holmes-Farley]

What effect does that have coming out of the membrane on di resin? Would it last longer with more sodium vs mag and cal? Granted it was “let’s say 5” coming out of the membrane hard or soft water to begin with..

The DI will be depleted a little bit faster, but the preservation of the lifetime of the RO membrane is usually a higher priority.

 

[Troylee]

The DI will be depleted a little bit faster, but the preservation of the lifetime of the RO membrane is usually a higher priority.

Sounds like I need to invest in a 55gal drum of di resin then haha.. I was hoping a Softner would help with that issue.. either way my pipes should last longer in my house since the hard water is eating this copper up!

 

[Reefer1978]

The DI will be depleted a little bit faster, but the preservation of the lifetime of the RO membrane is usually a higher priority.

@Randy Holmes-Farley can we make an experiment to prove this out one way or another? I am very confused to be honest. I am seeing improved TDS readings on both RO systems now that Softener is installed. And I am also seeing 80% less DI consumption. I trust your knowledge fully, so I am trying to figure out what am I missing?

 

[Randy Holmes-Farley]

@Randy Holmes-Farley can we make an experiment to prove this out one way or another? I am very confused to be honest. I am seeing improved TDS readings on both RO systems now that Softener is installed. And I am also seeing 80% less DI consumption. I trust your knowledge fully, so I am trying to figure out what am I missing?

Sure, an experiment would be interesting, but a bit of a pain.

If you bypass the softener (is it plumbed so you can do that? That is send tap water around it and into your pipes?) and flush through to empty the pipes and get the hard water back to the RO/DI, then monitor the pre and post RO membrane TDS amd compare those two values to the values when running the soft water.

FWIW, anything you do that changes the water pressure can impact the membrane performance.

 

[DShay]

I also have very bad local TDS water. Sometimes up to 750 TDS. I was also burning through expensive DI until I added a second stage RO unit with booster pump. Now I go from 600-750 TDS in, down to about 10-20 after the first RO stage, to 2-4 after the second stage and finally 0 out of the DI.

 

[Troylee]

I also have very bad local TDS water. Sometimes up to 750 TDS. I was also burning through expensive DI until I added a second stage RO unit with booster pump. Now I go from 600-750 TDS in, down to about 10-20 after the first RO stage, to 2-4 after the second stage and finally 0 out of the DI.

How do you have them tied together? In series like the clean water from membrane one feeds the second membrane? I could imagine going into a membrane at 20tds it should come out zero on the second but I could be wrong… I know there is a piggy back kit for a second membrane but I don’t think it helps much from what I researched.