Distilled vs RODI water

[oysterk]

Which is better? I've always used RODI, but at the tank I set up at my school, I've been using distilled.

 

[Duane Clark]

Which is better? I've always used RODI, but at the tank I set up at my school, I've been using distilled.

Honestly they both work. I don't think, IMO, one is better than the other.

 

[Gareth elliott]

Which is better? I've always used RODI, but at the tank I set up at my school, I've been using distilled.

The main difference is going to be cost. Distilled water costs much more than ro/di. The cheapest ive seen distilled water is .89/gallon. At an lfs most ro/di is like .30-.50/gallon. Home ro/di unit even cheaper but more expensive up front.
Smaller tanks this isnt an issue but once you hit 25-30 gallons and above basic home ro/di unit will pay for itself within a year.
Distilled uses heat to vaporize water and collecting the vapor.
Ro/di uses membranes to separate just the h20.
Heating costs more than membranes.(that $3 bottle of smart water probably cost .20 with the bottle) lol

 

[NY_Caveman]

With distilled, you always get pure water. Even 0 TDS RO/DI can have traces of things in it.

I note, for those who rely on an LFS, I am setting up a small system and went to three LFS this weekend looking for RO/DI water. All three claimed to have 0 TDS and one even seemed surprised I asked ("It's RO/DI water..." he said). I tested each place. One had 41 TDS, one had 14 and one had 7. 41 around me is worse than my tap BTW. I know this is slightly off topic, but always test. Never assume.

 

[NY_Caveman]

Just adding, I consider all three of these good LFS. Clean tanks and great corals. I know membranes degrade, etc. but even the experts can make errors. Always test.

 

[amazongb]

With distilled, you always get pure water. Even 0 TDS RO/DI can have traces of things in it.

I note, for those who rely on an LFS, I am setting up a small system and went to three LFS this weekend looking for RO/DI water. All three claimed to have 0 TDS and one even seemed surprised I asked ("It's RO/DI water..." he said). I tested each place. One had 41 TDS, one had 14 and one had 7. 41 around me is worse than my tap BTW. I know this is slightly off topic, but always test. Never assume.

I’ve used Distilled, but I would visit the manufacturers website for TDS info, and some had as much as 4 TDS.. so it’s a good idea to check with the maker before buying...

 

[Lovemyreef2015]

RODI is a purer/cleaner water and more cost effective than distilled. Good article on water and more hub for the similarities.

 

[NY_Caveman]

I’ve used Distilled, but I would visit the manufacturers website for TDS info, and some had as much as 4 TDS.. so it’s a good idea to check with the maker before buying...

Wow. I have always gotten 0 TDS from store bought distilled, but I always test, so great point.

 

[Gareth elliott]

Wow. I have always gotten 0 TDS from store bought distilled, but I always test, so great point.

I would be more worried about the things i cant test for like metals. That might be from the bottling or transportation process not the distilling.

 

[oysterk]

Oh that's great to know. Cost isn't an issue, since our school has an actual water distiller for the lab. Why do more people not by more home distillers then? Costs about the same as an RODI unit.

 

[Gareth elliott]

Oh that's great to know. Cost isn't an issue, since our school has an actual water distiller for the lab. Why do more people not by more home distillers then? Costs about the same as an RODI unit.

Besides the unit the still requires a lot of energy to operate.

To heat 20 gallons of water by 142°F in 30 mins (0.5 hrs); 3.1 x 20 x 142 / 0.5 =
17,608 Watts

Say you do 52 pwc a year of 5 gallons you will need to do this 13 times a year. 228,904w
All of this without any resisting force and starting at room temperature.
That would get expensive

 

[NY_Caveman]

Good question. I actually looked around and considered it. I am guessing RO/DI is better for large systems as the home distilled systems create small amounts of water over a longer time period.

I do not have room for an RO/DI system (considering the bins for waste and storage). My new aquarium is only 30 gallons. I planned on using RO/DI from LFS, but my post above has put that in question. Most distilled units are fairly expensive, but not all. I found one from www.H2Olabs.com for $150 that produces one gallon at a time in 5 hours. Not super convenient. However, considering I will need about 5 gallons a week for water changes and ATO, a gallon a day produced would be more than enough. And I never have to change any membranes. I note though, the unit uses 600 Watts of power.

 

[Rich Ogden]

go to BRS. You can get an inexpensive ro/di and I fill an 18 gallon tub in 3 hours for water changes on my big tank. It takes about 40 min to fill a 5 gallon jug like you will fill at the LFS

 

[Rich Ogden]

Go to BRS (bulk reef supply). I have a unit that creates 18 gal DI/RO water in 3 hrs. I fill a 5 gal jug in about 45 min. The waste water goes down the drain. I run a system where it runs the waste back through so you get more water and less waste. You can bottle the waste to use on plans or in other places if you are concerned about that. You can get a 4 stage system for about $140 and either get a water saver system, or add the water saver package at a later date for $60.

 

[roberthu526]

I would think distilled is more pure than RODI but that is based on theory only. Also distilled should be more expensive than RODI in general. But my tap water is only 45 TDS so I just use RODI.

 

[Tahoe61]

The issue I see with distilled is the pH, I believe it's a neutral 7.0. For top off that might be an issue in larger tanks, for mixing salt I have never had an issue using distilled.

 

[Gareth elliott]

The issue I see with distilled is the pH, I believe it's a neutral 7.0. For top off that might be an issue in larger tanks, for mixing salt I have never had an issue using distilled.

Ph of either if properly filtered should be no concern. Both should have no buffering agents. Ph of ro/di tends to slide to the acidic side because of gas exchange. I suspect distilled would do the same if ph was tested after sat in an open container. Either way once added to the tank should have a zero net effect on ph of the system added. As the evaporated water being replaced left behind its buffering agents in the system. At least my understanding lol.

Really i would be concerned with cost and possibility of say copper contamination during bottling or truck transportation. Copper to have a negative effect requires ppb our tds meters only measuring ppm.

 

[Jose Mayo]

RO / DI water (standard) is much purer than distilled water. There are contaminants that form azeotropic mixtures with water, which are not separated in the distillation and may compromise the final result. On the other hand, most distillers are made of metal and the highly reactive pure water vapor condensing on these surfaces can acquire metal ions of varying species and concentrations depending on the alloy on which they condense. Pharmacies and laboratories that require ultra-pure water for their applications, use RO / DI water.

Ultrapure water

Best Regards

 

[Duane Clark]

I'm currently using distilled water but will be switching soon. My issue is just how to set an RO/DI system up. A handyman I am not.

 

[ChrisOFL]

I'm currently using distilled water but will be switching soon. My issue is just how to set an RO/DI system up. A handyman I am not.

This is so much easier than it seems. You're literally just going to unscrew the aerator screen where the water comes out of your faucet and attach a nozzle or you're going to unscrew the water line under the sink with a wrench and attach an adaptor for the RO/DI, all done with just a wrench. YouTube is great for a visual how-to so you can see what to do step by step much clearer than what words can explain.