DI exhausting in less than a month?

[liz62]

Anybody know what would cause my DI to deplete in less than a month?

Only doing biweekly water changes and auto top off for a 75gl.
All filters and membrane changed in the last 4 months.

 

[sean2sean]

do you have a inline tds meter? if after ro and you are getting less then 10 ppm. then most likely you have high co2 in your water.

im in the same boat as you.

only way to save prolonging the di resin is to airate the ro water for a day and pump it through the di housing after a day or two.

 

[liz62]

inline TDS meter reads 0ppm.
I use to get months out of my DI but lately it doesn't last longer than a month.

 

[erickc23]

Is your water passing through the DI before or after the RO membrane? If it it's before that is why your DI doesn't last. The DI should be last. I hope that helps.

 

[sjm817]

What is your TDS before the DI stage?

 

[cham]

Pretty good chance your RO membrane needs to be replaced.

 

[liz62]

replaced the membrane 4 months ago.
The DI is after the membrane - it is the last stage.

 

[sjm817]

You need to measure the TDS before the DI stage. If something is wrong such as a membrane that is not seated correctly or a bad membrane, you will have high TDS going to the DI stage which will rapidly deplete it.

 

[liz62]

ok I will check it tomorrow.
How will I know that the membrane isn't seated properly? what should I look for if I take it apart?

thanks for the replies guys.

 

[sjm817]

Its hard to tell visually. Did this start just after you replaced it?

 

[liz62]

It was around the same time I think?

 

[sjm817]

It may be a membrane not seated well then. Take it apart and see how everything looks.

 

[liz62]

If it is not the membrane do you have any other ideas?

 

[sjm817]

The basics...a membrane can reject ~ 90 - 98% of the TDS depending on what type it is. Say you have a tap water TDS of 250. After the membrane that is a TDS of 5 - 25. Whats left after that, the DI cleans up. If the DI is doing all the work, it will be exhausted very quickly. The prefilters dont do all that much to lower TDS. If you are getting a high TDS to the DI, the membrane isn't working right. Its not seated properly, maybe the flow restrictor is not the right one for the membrane. The problem started after you replaced the membrane so its a likely candidate.

 

[liz62]

Ok thanks a lot Scott - this will be project for today (after golfing). I will post what I find - hoping that the membrane is not seated properly!

 

[Kungpaoshizi]

how big is the di chamber, what kind of resin (brand, mixed/separate bed), how do you store it inbetween uses, you use warm or cold water, and yes, what's the tds RIGHT before the di chamber coming out of the RO membrane...

 

[liz62]

Ok I took it all apart and put it back together.
The membrane looked fine to me although I wouldn't know if it was seated or not?
I checked PSI after membrane - it was 58 psi and before membrane and it was 65 psi.
I haven't checked the TDS before the DI - I forgot but the inline is readying 0 TDS after the DI.
I guess I better head back down to the bsmt. and check that.

 

[liz62]

the resin is color changing from BRS and it is a standard 10" canister. I use cold water - it is tapped right into the cold water pipe. I store the resin in it's sealed bag.

 

[Toddrtrex]

inline TDS meter reads 0ppm.
I use to get months out of my DI but lately it doesn't last longer than a month.

If your inline TDS meter is reading 0, how do you know that your resin is exhausted?

 

[liz62]

it is color changing resin - I get 0 TDS until the resin is exhausted.
My point is that I am exhausting the resin in about month -ie/ I am changing the resin monthly. The resin use to last months.