High TDS in new RO system

[schinkowski]

Hi,
I just joined to forum to ask this question.

I got a reverse osmosis system capable of producing 150 US Gallons of water a day. I connected it and left it running for over 2 hours, but the output TDS were still quite high. I measure the TDS in-line, input is 60 and output was 50. My pressure was only around 20psi, so I got a booster pump. With this my pressure is close to 40psi but my output TDS is still only 35.
It's a D-D booster pump and I can't see a way to increase the output pressure on it.
Would a lower grade membrane work better with my low water pressure and produce higher quality water?
It's a 3 stage RO system with a 5 micron pre-filter, a 10 micron block carbon filter and the membrane.

Thanks!

 

[fort384]

With pressure that low, I don't think these specs are out of line with what you should expect. Without getting pressure up to 60psi or so, especially on a 150gpd system, I would expect a TDS of 15-30 or so ppm.

 

[schinkowski]

Thanks for your reply.
So would I get 0 tds if i switch to a 50 Gallon/day membrane?

 

[fort384]

no, you wouldn't. You aren't going to get 0 TDS out of an RO system. It would require the addition of a deionization (DI) stage.

 

[schinkowski]

Yeah, I mean closer to 0, I also have DI resin but didn't connect it yet because I want to figure out how to get below 10 or so from my membrane.

 

[fort384]

Increasing the pressure to the membrane would help some, I am sure. Adding an additional carbon block to the system would also help.

 

[schinkowski]

I don't think I can increase the pressure any more, I'm already using a booster pump.
I'll look into getting a second carbon block.
Thank you.