Rodi tds

[seeky007]

Hi everyone
I HAVE JUST INSTALLED A WATER BOOSTER PUMP ON MY RODI UNIT MY TDS IS 7 COMONG OUT OF THE CLEAN LINE AND THATS BEFORE THE DI STAGE IS THAT GOOD OR SHOULD I GET ANOTHER DI STAGE.

 

[gbroadbridge]

TDS of 277 into the membrane and 7 out is very good.

The DI stage will reduce that to zero

 

[marinesnow]

TDS of 277 into the membrane and 7 out is very good.

The DI stage will reduce that to zero

This.

 

[TX_REEF]

DI should be able to take down to zero from 7, test the water coming out of DI.

 

[seeky007]

Thanks
I will put a tds meter after the di stage that would the right move I think.

 

[gbroadbridge]

Thanks
I will put a tds meter after the di stage that would the right move I think.

Yes, that's the one that tells you when you need to change the DI resin.
When the TDS increases to 1 or 2 change the resin.

If that happens too frequently a 2nd DI stage will prolong the time between changing the resin.

I have a single stage of DI resin and it lasts me about 6 months, but everyone has different results

 

[seeky007]

Yes, that's the one that tells you when you need to change the DI resin.
When the TDS increases to 1 or 2 change the resin.

If that happens too frequently a 2nd DI stage will prolong the time between changing the resin.

I have a single stage of DI resin and it lasts me about 6 months, but everyone has different results

Thanks for the information.whats your take on adding uv?

 

[mikst]

Since you've tested the output, what's the tds of the waste water?

I live in California and my water is both metered and not cheap so I'd rather not be dumping water if it could be used elsewhere if I decide to get an rodi filter.

I am pretty sure the waste water TDS would be dependent on the input water TDS and would likely be scaled linearly. My home's tap
water TDS is pretty low at only 45ish.

 

[KStatefan]

Since you've tested the output, what's the tds of the waste water?

I live in California and my water is both metered and not cheap so I'd rather not be dumping water if it could be used elsewhere if I decide to get an rodi filter.

I am pretty sure the waste water TDS would be dependent on the input water TDS and would likely be scaled linearly. My home's tap
water TDS is pretty low at only 45ish.

It will depend on you incoming water TDS, membrane rejection rate and waste to permeate ratio.

If you had 100 incoming TDS and a 4:1 ratio with a 95% rejection your waste water wound be 124 tds

 

[mikst]

It will depend on you incoming water TDS, membrane rejection rate and waste to permeate ratio.

If you had 100 incoming TDS and a 4:1 ratio with a 95% rejection your waste water wound be 124 tds

Great, thanks for the calcs. Does 95 percent rejection mean for each liter of water produced, 19 liters are rejected as waste?

 

[KStatefan]

Great, thanks for the calcs. Does 95 percent rejection mean for each liter of water produced, 19 liters are rejected as waste?

No 95% rejection means 95% of the dissolved solids are removed