Deionized water

Is Deionized water the same as r/o water? if not what is the difference and which one would be better to use. I am moving in a few weeks and called the local water purification company and asked if they sold r/o water and the lady said they only sold deionized water. I should have asked her the difference, but just said ok thanks. So I come to you and ask, whats the difference?

 

its good for your tank.. what price per gallon did she say it was?

 

They both are different
Reverse Osmosis (RO) & Reverse Osmosis/Deionization System

 

DI water is purer than RO water. Generally people will have an RO/DI unit which first goes through reverse osmosis (RO), than through the DI. DI cartridges will get used up very quickly if the water that passes through them isn't already extremely pure (like reverse osmosis water). To use just a DI cartridge and put normal tap water through it- it'll burn the DI cartridge in a week if you use it often enough.

So if they're selling DI water you can feel confident that it's pure enough for your aquarium - as long as they're replacing the DI cartridges as often as they should be.

So to answer your question : DI water is better than just RO water. (DI is just one step above RO in terms of purity).

 

I called the local water store and she quoted me a price of .25 a gallon. I asked for R/O and she said they only sold DI. From what you all are saying this could be a good thing.

 

I persoanlly think she is confused as only DI water is odd it would have to be rodi. as one process leads to the other. as RO first and then DI.

You can drink rodi water but not alot of it, as it will harm you. I think she means she sells ro I would ask her the difference and also compare to what others are posting.

As for the price it is a good price for the water. the 2 most pure waters for a reef would be rodi and distilled

 

Just to add a link to an article discussing this type of info.
Reverse Osmosis/Deionization Systems to Purify Tap Water for Reef Aquaria by Randy Holmes-Farley - Reefkeeping.com

EDIT:
I agree, AFAIK it would be silly to just send water through a DI filter without going through an RO membrane first. Most DI canisters we get for our RO/DI filters will only get around 50 gallons of about 100 TDS water down to zero TDS where we want it. That's really inefficient for the cost of a DI cartridge/refill. The idea behind the RO/DI filter is that each stage complements the following stages so you get the maximum amount of filtering from each stage.

Generally it goes sediment filter which filters out large physical particles for the most part, then carbon which mostly is designed to get rid of large molecules of dissolved compounds like chlorine etc, then it goes into the RO membrane which should take out 90%+ of the remaining dissolved solids and then the DI canister should take the remaining single digit TDS water down to zero TDS. The RO membrane can last for years depending on usage so it really does the bulk of the filtering work without having to replace the DI canister every week/couple weeks. The filters before the RO membrane are relatively cheap and keep the RO membrane in good shape so it doesn't wear out prematurely.

Ultimately whatever you end up doing for your water supply, get a TDS meter and make sure it's zero TDS water you're buying or using from your filter.

Hope that helps.

 

Why would it harm you?

 

It is indeed possible to filter using a DI only. In fact, the tap water purifier from Aquarium Pharmaceuticals filters using DI resins only.

 

Drinking RO water is fine but DI is supposedly not. This topic, however, is highly debated:

Human consumption of deionized water