RO/DI Unit Question

[dileggi]

Hey guys,

I'm looking into purchasing an RO/DI unit. It was suggested that I get a TDS meter with it.

My question is this: Do I really need a TDS meter? And, what does it do?

Any help would be greatly appreciated!

Thanks!

[phenom5]

Do I really need a TDS meter? And, what does it do?

Yes, you need a TDS meter. A TDS meter measures the amount of Total Dissolved Solids in your water. It is key to ensuring that your RO unit is operating effectively, and helps you determine when you need to change out your RO membranes.

[dileggi]

Thanks phenom. I just really had no idea if I needed it. One other thing...is there a big difference between using RO/DI water compared to using distilled water? I've been using distilled water.

Thanks again.

[95accord]

distilled water = best
RO/DI water = excellent

Distilled = expensive
RO = cheap...er......in the long run :P

[Randy Holmes-Farley]

This article details how to use a TDS meter with an RO/DI:

Reverse Osmosis/Deionization Systems to Purify Tap Water for Reef Aquaria
http://reefkeeping.com/issues/2005-05/rhf/index.htm

[dileggi]

Originally posted by 95accord
distilled water = best
RO/DI water = excellent

Distilled = expensive
RO = cheap...er......in the long run :P

So, it's actually better to use distilled over RO/DI?

Thanks 95!

Also, thanks Randy for the link to the article.

[Aquarist007]

Originally posted by 95accord
distilled water = best
RO/DI water = excellent

Distilled = expensive
RO = cheap...er......in the long run :P

I believe ro/di water is the best because it removes 100 per cent of dissoved elements

followed by r/0 water which removes 95per cent of dissovled elements

From randy's article quoted above:

Conclusions

RO/DI is likely the most effective way for reef aquarists to adequately purify all tap waters they are likely to encounter. Most aquarists will find that a standard system consisting of a sediment filter, a carbon filter, a reverse osmosis membrane, and a deionizing resin cartridge is perfectly suitable. It is also useful to have the ability to measure the conductivity of the effluent inline, and to measure the pressure across the RO membrane.

In some cases, it may be desirable to degas the incoming tap water if it contains excessive carbon dioxide. It may also be desirable to have two DI cartridges in series if there is a lot of silica or other easily penetrating problem ions in the RO permeate. If you have well water that smells bad or has other peculiarities, it may be worth discussing the issue with a top-of-the-line RO/DI system manufacturer to make sure that you are treating the water appropriately.

Whatever brand or setup you use, be sure to change the filters at appropriate intervals.

Happy Reefing!

[dileggi]

Thanks Capn. I just started another thread asking the difference between RO/DI and distilled prior to seeing this response.

I had read the articles on waterkeeping from Randy, and that kind of confused me more. He does state that the RO/DI is the best way of purifying tap water. I guess I'm confused becasue I was not considering distilled water tap water. Is that incorrect?

[scouncil]

Distilled water is not tap water, it's distilled, removing 100% of everything other than water. RO/DI removes 95% which is really good and and RO unit can be a one time purchase instead of having to buy distilled all the time (which get expensive if you have a 75+gal tank system....

[scouncil]

Distilled water is not tap water, it's distilled, removing 100% of everything other than water (you don't have to do anything to it other than mix in your salt mix). RO/DI removes 95% (from your own home tap water) which is really good and and RO unit can be a one time purchase instead of having to buy distilled all the time (which get expensive if you have a 75+gal tank system....

[dileggi]

Thanks for your reply scouncil. That about answers my question. I guess for now, I'll just forget about the ordering the RO/DI unit, and continue to use the distilled water. I agree on the expense portion if you have a large tank. Since I'm only changing 5g per water change, even if I did it weekly instead of bi-weekly, that's only $4.80 in water...until I get a bigger tank!

Thank you again!

[95accord]

distilled is the better choice quality wise....but when you take into consideration having to go out and buy water all the time.....Versus making your own water anytime you want at home....RO/DI water is just as good a alternative

convinience is a big factor.

my 0.02

[Largo50]

I've read that distilled water is risky if you do not know how it is distilled. If the distillery uses copper tubing for the distilation it leaches some copper into the distilled water, which is bad for invertibrates.

Distilled water also does not remove everything from the water. The highest quality lab grade water is double distilled water or bidest water.

[chillman]

Using a tds meter is a good habit to make sure your rodi unit is working properly. If you see the tds value climbing you know it is time to replace filter cartridges. It also is helpful in that you can test your water right out of the tap to know how much crap your rodi is filtering out of it.