Reverse Osmosis/ Deionizing questions...

[Xirxes]

Hello again,
Just picked up this unit right here http://cgi.ebay.com/New-6-stage-100-GPD ... dZViewItem

Few questions:
1. Is it really supposed to flow this slowly? (2 GPH?)

2. Measured pH after filter (expecting 7.0) and finding 8.8+?!?! Have read that it is not possible to measure pH of RO/D.I. water as it is unbuffered. is this what i am seeing? Or is it the in line carbon still showing up?

3. What TDS should i be seeing for this unit, in order to note whether or not it is working?

Thanks for any help i can get.

[MrSecant]

RO makes totally pure water. You should see pH of 7.0 but you are right about the buffer ability of the water. RO removes all the carbonate in tap water and thus, all the buffering capacity. Any small amount of acid or base will upset this.

TDS should be very near 0.

RO do generally flow very slowly as well. The more refined your filter, the larger the pressure drop across it. The smaller the pores in your filter, the harder it is to pass the same amount of water through them.

[Xirxes]

Works like a dream, although it takes 2.5 hours for 10G water change.

Heres some tidbits on why i needed an R.O./D.I. setup:

tested today to see the changes...

TDS (total disolved solids) believe in PPM:
Tap- 475
RO/DI- 46

Calcium believe in ppm as well:
Tap- 310
RO/DI- 0-20

Ammonia:
Tap- .5-.6
RO/DI- 0

Chlorine:
Tap- 1.0-1.5ppm (San Diego just started adding tons of chlorine to replace what used to be ammonia, now tap tastes like poolwater)
RO/DI- 0ppm

pH:
Tap- 7.8-8.0
RO/DI- assumed 7.0, but cant test due to lack of buffer.

Fishies seem to love it, and ive started bottling some of our own drinking water, the unit was easy to install, and i think well worth it.