RO/DI vs. Distilled

[Got Salt ?]

Ok......I've read some articles about RO/DI water. Currently I'm getting RO water from a local grocery store, but I'd like to eliminate that cost with my own system.

Keeping this simple, what is the better system....an RO or RO/DI system or a water distiller (condensed steam) ??

I am under the impression that RO/DI systems waste quite a bit of water at 2 or 3 gallons per gallon made, where a distiller may not remove compounds that vaporize at temps lower that 212 F. and will condense back into the distilled water.

Thanks!

 

[bertoni]

Distilling your own water is going to be very expensive, I think, due to the energy cost. It might not be quite as clean, although you could run it through a DI cartridge.

 

[homesidereef]

$$$$$$$$$$$$$$$$$

 

[AZDesertRat]

The electricity required to boil and distill water is prohibitive. A good RO/DI can be had for around $140 and the very best for only $269 right now.

 

[Got Salt ?]

I was leaning towards the ro/di system, just didn't like the thought of wasting a lot of water. Unless they don't use quite that much when making water. I'll keeping investigating.

 

[bertoni]

There are zero-waste RO-DI systems that inject the reject water back into the hot water tank, if you're interested in that. Might be costly.

 

[dga]

if your "city" water has a zero "tds" output, you may be able to eliminate the di stage, saving cost.

 

[AZDesertRat]

No city has 0 TDS. They treat water for drinking not reef systems. 0 waste systems have severe limitations biggest of which is they are limited to about 15 to 20 GPD.

 

[Got Salt ?]

Good feedback. I also read the RO/DI FAQ on the home page.

I figured out my water costs and $20-30/year in waste water (I'll use a lot of that in the garden when summer returns anyhow) vs. $179.40 in store bought water is quite a lot of other cool Reef goodies for me!!

I think its great to have a forum such as this with so many people sharing their interests in reefs and marine fish. That Rocks!

Thanks!

 

[dga]

<a href=showthread.php?s=&postid=8828860#post8828860 target=_blank>Originally posted</a> by AZDesertRat
No city has 0 TDS. They treat water for drinking not reef systems. 0 waste systems have severe limitations biggest of which is they are limited to about 15 to 20 GPD.

correct. i meant to say if your "r.o. output" from "city" water.

 

[AZDesertRat]

You won't find a RO with a 0 TDS output as they are a 98% efficient device at best with some in the 90% range. DI is almost always recommended.

 

[bevis28]

i have done the test on wally world "supposed" RO/DI/Deionized
water because i started using it and was getting algea blooms of HA and others. the TDS of that "so called " ro/di/deionized water is 17 !!! i bought a 4 stage ro/di unit and the TDS from the DI stage is ZERO. that TDS of 17 is coming from something..... i would steer away from their label statements. they are not telling you what micron size filtering that they are using or what type of RO membreane or how they DI it... obviously its not good enough for the reef system.

 

[dga]

<a href=showthread.php?s=&postid=8831860#post8831860 target=_blank>Originally posted</a> by AZDesertRat
You won't find a RO with a 0 TDS output as they are a 98% efficient device at best with some in the 90% range. DI is almost always recommended.

incorrect. using the 50gpd dow filmtec with a 5 micron and 1 micron carbon block prefilters, here in michigan, at point source i usually get around 90-95 tds b4 filtering the r.o. output is 0 tds. measured with a pinpoint monitor and handheld hm digital monitor. i still use di, as its not expensive and my tank inhabitants are.

 

[bertoni]

What's the input TDS?

 

[AZDesertRat]

You are getting an indicated 0 on a device that is +/- 2% of full scale which can be as far off a 20 TDS. Not to argue but RO membranes are not magic and they do not remove everything. It takes carbon before and DI afterwards to get a true 0 TDS. I'll bet money with an HM Digital COM-100 meter you will find what you think is 0 is in fact not. Read Spectrapures writeup on 0 TDS in their sponsors forum, its pretty good reading.

 

[dga]

<a href=showthread.php?s=&postid=8833939#post8833939 target=_blank>Originally posted</a> by AZDesertRat
You are getting an indicated 0 on a device that is +/- 2% of full scale which can be as far off a 20 TDS. Not to argue but RO membranes are not magic and they do not remove everything. It takes carbon before and DI afterwards to get a true 0 TDS. I'll bet money with an HM Digital COM-100 meter you will find what you think is 0 is in fact not. Read Spectrapures writeup on 0 TDS in their sponsors forum, its pretty good reading.

i realize that and dont dispute it. i stated that the "measured" tds was 0 on my meters. that is why i run di resins after the r.o.