RODI DI TDS starts high even after flush and valve

[Dweezilz]

I have a SpecraPure MaxCap90, a Smart buddy pump which flushes the membrane every time it's turned on for the first 30 seconds and a valve to divert the first few gallons of water out of the membrane to take care of TDS creep. When I turn the water on it flushes the membrane for 30 seconds and then my TDS starts high out of the membrane for about 3 or 4 minutes until it gets to 2 TDS. I have this water going into the drain out of the membrane until it's 2 TDS, so I know I'm only sending 2 TDS to the first DI canister. I check TDS in-line and with a good handheld...it's 2 TDS (handheld usually says 1). My problem is that what comes out of my 1st DI is usually around 17-25 TDS for a few minutes going to the 2nd DI and finally goes down to sending 0 to the 2nd DI. I've check this as well with in-line and handheld. If the membrane only ever sends 2 TDS to the first DI, how is it that after the unit sits for a few weeks the 1st DI has 17 TDS in it? I added a valve to divert the 1st DI to the drain for a few minutes to conserve the 2nd DI. Is this normal? How is that happening?

 

[MnFish1]

I have a SpecraPure MaxCap90, a Smart buddy pump which flushes the membrane every time it's turned on for the first 30 seconds and a valve to divert the first few gallons of water out of the membrane to take care of TDS creep. When I turn the water on it flushes the membrane for 30 seconds and then my TDS starts high out of the membrane for about 3 or 4 minutes until it gets to 2 TDS. I have this water going into the drain out of the membrane until it's 2 TDS, so I know I'm only sending 2 TDS to the first DI canister. I check TDS in-line and with a good handheld...it's 2 TDS (handheld usually says 1). My problem is that what comes out of my 1st DI is usually around 17-25 TDS for a few minutes going to the 2nd DI and finally goes down to sending 0 to the 2nd DI. I've check this as well with in-line and handheld. If the membrane only ever sends 2 TDS to the first DI, how is it that after the unit sits for a few weeks the 1st DI has 17 TDS in it? I added a valve to divert the 1st DI to the drain for a few minutes to conserve the 2nd DI. Is this normal? How is that happening?

If I'm understanding - you're saying - when your system is off - initially the TDS of the end product water starts out higher than 0 - then falls to 0. This is normal behavior - and probably relates to something that is being flushed out of the tubing if it's sat for a while.

 

[Dweezilz]

If I'm understanding - you're saying - when your system is off - initially the TDS of the end product water starts out higher than 0 - then falls to 0. This is normal behavior - and probably relates to something that is being flushed out of the tubing if it's sat for a while.

Yeah, sort of. The water going into the first DI has never been higher than 2 but after it sits for a few weeks that 1st DI sends out like 17-26 or so for maybe 30 seconds or so and returns to 0. So basically because water is sitting at the top and in the tube for a few weeks the TDS goes up, right? I'll continue to run that to the drain for a minute before sending to the 2nd DI. Thanks for the help!

 

[Dbichler]

Correct water will gain tds sitting there either run your rodi system more often or continue flushing it before storing it and watch the tds before hand no issues either way