Why RO/DI? Why not just RO or just DI?

[mhhauser]

This is what I know, lets see if anyone can help.

Well in water quality, it goes

1st RO water
2nd DI water
3rd Distilled Water

I know that you can get Ro water and mix it with Tap and that makes a good combo.

Also I think you can do the same for both DI and Distilled water.

If this is wrong, plz tell me somehow, Via PM or posting.


So I guess My question is Why RO/DI? Why not just RO or just DI?

 

[dchao]

Just RO: you might still get trace of chlorinmines (if your tap water contains this horrible stuff), which is bad for the fish.

Just DI: Resins used up too fast, and resins are expensive. RO wastes a lot of water, but water is cheaper than resins.

 

[Andrew]

DI is just an added bonus which helps. You can get just a plan RO unit buts its not as good as a RO/DI unit.

 

[javajaws]

If you don't need alot of water however, a DI only setup may be cost effective for you when you subtract the additional hardware costs of the RO unit. Knowing your tap TDS could help in this sort of decision as well since the tap quality is directly tied to how long the DI resin in a DI only system will last.

 

[Ann1214]

I am using a RO unit, and wondering if I need to add a DI setup to it. The phosphates test at 1 ppm. Is this too high?

 

[javajaws]

Is that 1 PPM out of your RO? Or your tank water? If your RO is 1ppm...then yes, that is too high. Its too high if it is your tank water as well, but the cause might not be your RO water.

 

[dtaranath]

in that case, what would be a good ro/di unit?

 

[NeilPearson]

<a href=showthread.php?s=&postid=6528182#post6528182 target=_blank>Originally posted</a> by dtaranath
in that case, what would be a good ro/di unit?

One of the ebay ones for around $100

Get the 75 gallon per day RO instead of the 100 gallon per day. It works better and your DI resins will last a lot longer.

 

[javajaws]

I'm not a fan of any unit that has the smaller sized DI cartridge or anything less than a 98% rejection rate RO membrane.

 

[old salty]

I use an RO/DI, but I think the biggest benefit of this is that I use the RO only water for my freshwater tank and for drinking and cooking. Coffee tastes so much better when the water doesn't have chlorine in it.

 

[crumbletop]

I recently purchased a typhoon setup from airwaterice. It was easy to set up and works great. They also have very good customer service.

http://www.airwaterice.com/product/1TYPHOON

 

[IslandCrow]

Where does distilled fit in amongst water quality. I seem to remember reading that distilled is actually better than either RO or DI. It seems to make sense to me, but does anyone know for sure? I don't currently have an RO unit, so I use a combination of distilled (they sell it really cheap at WalMart) and RO/DI I get from my not so local fish store.

 

[mastermind73]

Just bought a Kent Maxxima RO/DI. Works great and easy to hookup, but i think airwaterice makes the best ones and even comes with lots of extras like TDS meter and hookups. Its very expensive (including shipping) though.

 

[javajaws]

<a href=showthread.php?s=&postid=6529966#post6529966 target=_blank>Originally posted</a> by mastermind73
Just bought a Kent Maxxima RO/DI. Works great and easy to hookup, but i think airwaterice makes the best ones and even comes with lots of extras like TDS meter and hookups. Its very expensive (including shipping) though.

Very expensive? A Kent Maxxima 60 GPD is around $200. The Typhoon III 75GPD is $200, and includes the extras you mentioned and more plus an extra filter chamber. Shipping is less than $25. I'd hardly call that "very expensive" when you compare against units from Kent or Spectrapure. "Bargain" is a better word...

 

[javajaws]

<a href=showthread.php?s=&postid=6529913#post6529913 target=_blank>Originally posted</a> by IslandCrow
Where does distilled fit in amongst water quality. I seem to remember reading that distilled is actually better than either RO or DI. It seems to make sense to me, but does anyone know for sure? I don't currently have an RO unit, so I use a combination of distilled (they sell it really cheap at WalMart) and RO/DI I get from my not so local fish store.

Some reading for you (from a generic search on distilled water):

http://reefcentral.com/forums/showthread.php?s=&threadid=747890&highlight=distilled

http://reefcentral.com/forums/showthread.php?s=&threadid=746742&highlight=distilled

So there is the possibility that depending on the equipment they use to distill the water, that there may be some copper in there. You probably won't be able to tell if this is true for your distilled water or not unless you test it. I'd take the safer route and go with the RO water instead.

 

[IslandCrow]

Good info you found there, javajaws. I hadn't thought about copper being used to make some distilled water. I guess the good news is that I haven't killed any of my inverts, so if there is any in the distilled water I'm using, it's not toxic. It is making me think much more seriously about getting an RO/DI unit sometime in the very near future, though. Time to start researching units. . .

 

[javajaws]

The best bang for your buck IMO is Typhoon III from airwaterice...not as cheap as the eBay units, but when you look at what you get for that price its a good deal.

 

[dtaranath]

any difference between Typhoon I and III, other than the extras?

 

[javajaws]

Pretty much...I believe it lacks the pressure gauge, RO only output, and the fast flush features.

 

[WaterKeeper]

Just as a note here. Some people drink the distilled water available in stores. When the EPA passed the rules regulating copper in drinking water almost all distillers changed out the copper condensing coils in favor of tin, glass or marine grade stainless. This allows them to sell the water without placing a warning on it about possible elevated copper levels.

Distilled water is of higher quality than RO but it is nowhere as pure as DI water. The best triple distilled water, made in a quartz still, is only about 2 million ohms resistance while DI gets close to 18 million ohms (absolutely pure water has a resistivity of 18.33 million ohms). For aquarium use either will do but I did want to point that out. For more on the subject see [rodifaq].