RO/DI Advice

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kalristo

kalristo

Well-known member
Joined
Dec 21, 2009
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Location
Tacoma
my fello reefers,

so my parents want me to look into RODI systems and i talked to thefilterguys.biz and they recommended the $199. unit that does everything i need 75GPD and the capabilities of producing drinking water
now for the questions:

1) how pure is the drinking water compared to the "water to go" places i go to buy water

2) what differences do you think there are between this $199 unit vs the $90 dollar units people are talking about from EBAY?

3) is there a better alternative?

im willing to spend $239 shipped for their unit, however i just need to justify it to my parents why to buy it.

id rather buy the best the first time then going back and buying the same product somewhere else later down the line

THANKS ALL!

-KALVIN
 
Well, I've give this one a try, as non-biased as possible ;)

1) in general, assuming you maintain your RO/DI unit by checking for dirty/clogged filters, etc (general maintenance), you're drinking water should be as pure or purer than anything you buy from a outside source. If you really want to know, you should use a TDS meter to measure. Then, at least you'll know how much "total dissolved solids" there are in the water. On that subject, keep in mind some drinking water, such as mineral water, will have TDS (i.e. the minerals, etc) that are probably not "bad" for you (probably even good for you). In fact, the general recommendation I've heard regarding RO/DI water is that you shouldn't drink it because it's overly pure. So, I believe you'll find that RO/DI units designed/sold with capabilities of producing drinking water will bypass the DI part for the drinking water (that's how mine is set up at least). But to answer your exact question, your RO/DI should be as pure or purer.

2) I believe when comparing RO/DI units, you should look at the "hardware" and then the "software". By that I mean the housings, frame, gauges, meters, hoses, etc are the hardware. And, the filters and membrane are the software. In general, the hardware is probably going to be very similar across different brands. However, take a look at the size of the housings to determine if they are smaller than "normal". Also, take a look at the orientation of the DI chamber(s), as some will tell you there's a quality difference between horizontally vs vertically orientation. You'll probably find that more expensive units have some extra hardware, like pressure gauge, tds meter, drinking water add-on, bypass valve (good for RO membrane maintenance), etc. Regarding "software", I believe you'll probably find that the more expensive units use brand name membranes & filters, with possibly higher "ratings". However, keep in mind that if you do go with a cheaper unit, eventually you're going to replace all the software, so you can buy more or less expensive brands of your choosing later down the line.

3) I think some of the pluses from buying from a vendor would include: guarantee/warranty support & customer service support in general. I know many RO/DI vendors have great reputations for spending time to answer customer questions both before & after the sale, whereas eBay sellers are going to be hit & miss.

Anyways, probably rambled on too long :) Not sure how well I concealed my bias either... Based on your last line "id rather buy the best the first time...", my recommendation would be to buy it through a reputable dealer, such as thefilterguys.

HTH,

Rob

ps, the above are all generalizations and I'm sure there are exceptions to what I've said...
 
Last edited:
I can testify for the filterguys, call them anytime for help & see the service. Their filters are the best out there, there is a such thing as less quality membranes or various other filters!
Just to add to what was mentioned, also take these as Opinions, anything good or bad can happen wherever you decide to buy. The e-bay chepies I'd beware for the $99 specials. JMO
 
thanks roblou & scooterman i think ill probably go with what i wanted to do in the first place and go with the filter guys.

how is a water "bad" to drink if its overly pure? the one im looking to buy is supposed to have a digital TDS meter to let me know what my water levels are at.

the last thing im confused about is that if the unit creates PURE water for salt water aquariums then whats the difference between drinking that "pure" water vs filtering it a last time through the unit of the far right?

OCEANREEF1.jpg
 
That’s a good question about the drinking water vs the aquarium water. I saw that in a few ads as well where the unit is designed to be for reef and drinking water. It seems like the drinking water bypasses the last DI filter and goes threw another carbon filter. Whats the deal with that? The second and third stage in most of the filters are already carbon?
 
Well, I'm no expert...but I did stay at a Holiday Inn Express last night...

Reverse Osmosis removes most of the mineral content from water, whereas Deionization removes all the minerals (or in the case of our RO/DI systems, the remaining minerals). Take a look at the "Health Effects" section of this link http://en.wikipedia.org/wiki/Deionization, it has a good explanation of why drinking water devoid of minerals isn't good for us.

So the drinking water kits for the RO/DI units take the drinking water off the system between the RO and DI stages so it has some beneficial mineral content.

The carbon prefilters on the RO units are to remove certain compounds which can degrade the RO membrane. A second carbon filter after the membrane is sometimes used to remove any chemicals the membrane missed...probably over kill.
 
Here is my understanding about RO/DI water in a simplistic overview (this is all based on what I remember reading, so hopefully I'm remembering correctly). After water goes thru the DI stage, it is "ultrapure", close to 0 TDS, assuming the DI isn't exhausted (vs RO water, which removes up to ~98% of TDS, but still leaving measurable TDS). 0 TDS is an unnatural state for water, as it normally will attract impurities which get "absorbed" into the water (osmosis). I believe 0 TDS water left out in an open container will absorb TDS over time from both the container it's in and the air in contact with the water (which I believe is why most recommend RO/DI water should be stored in a container with a lid). I think the theory why RO/DI water isn't so good to drink is that it can actually remove nutrients from your body. How true that is I cannot say. I'd guess that this could be true if someone only drank RO/DI water for a long extended period of time, and I'd certainly think you wouldn't die or get sick from drinking RO/DI water on occassion. Probably a doctor could answer better that I...for all I know this could just be urban legend...

So the difference when used for your aquarium water is that you take this "ultrapure" water and then add the expensive salt mix into it, which is more than just salt...it's a balanced mixture of salt, calcium, buffers, trace elements, etc. Basically everything needed to make synthetic salt water..."just add water". By using RO/DI water, you have some assurance that the mixed-up salt water doesn't contain any TDS that can be harmful to your livestock. Of course, if the salt mix you're using is a bad batch, then the water could be bad regardless of RO/DI or not (if you search you'll find threads about bad salt batches).

Anyways, I hope I somewhat accurately answered the question. If not, someone please correct me...

HTH,

Rob
 
Heh, I took so long to write my post someone else answered first, and provided a good wikipedia link to boot ;) Thanks gothunder!
 
The unit you have in the pic looks good:

1. has pressure gauge, which is a good indicator of when your prefilters will need to be changed (pressure will drop as the filters get clogged)
2. has tds meter. I can't tell if it's a single or dual tds meter. If it's single, you might want to see how much extra for a dual. On a single, depending on where the probe is positioned, it'll help determine when RO membrane OR DI chamber needs to be changed, but not both. A dual meter will allow you to position a probe between the RO to DI stage, and the 2nd probe after the DI stage. IMO, probably worth it if it's not too much to upgrade.

One thing I don't particularly like is the RO membrane housing is not clear. This is just a personal preference, but I like to be able to see the membrane. They may have a clear housing if you ask.

Also, if your budget allows, you may want to ask how much to add on a flush kit. A flush kit allows you to flush the water sitting stagnant in the unit between uses, which helps improve the life of your DI resin. (Flush kit probably makes more sense for units that are permanently installed vs units only hooked up when in use).

Good luck!

Rob
 
+1 on the Ocean Reef+1. I've been running the exact unit for over a year now without issu(one exception, I do run a second membrane to reduce waste water). The TDS meter is dual, so you can set it up as Rob recommends. And it also comes with the membrane flush valve included. It's a sweet little set up for a reasonable price. Their customer service is exceptional.
 
My first RODI unit was a Ebay type of unit, it never did work right or get the tds below 7. After a year I bought the same unit that you are looking at from TFG and construction alone is a world apart. And the tds is 0: As far as the Rodi drinking water debate, you can just put in a couple valves (blue and white ones) to by pass the DI unit when you want to make drinking water. I make 5 gal at a time.
 
I have a question, Not to hijack this thread, but while we are talking about RO/DI units,

1) For every gallon of pure water how much waste water will there be (on average)?
2) I've seen in the grocery store the Glacier water company uses a UV stage in the RO units. Is this benefical? Or would it be a waste of money? I've also seen their units have dual carbon stages, good or not necessary?

I am thinking of hooking up a unit with dual carbon and a UV sterilizer but still just in the thinking stages at this point.

Cheers,
Alex
 
Just a +1 for the Filter Guys!
My tank came with a Ro/DI from another company, The filter guys gave me all the info on how to set it up correctly. They also made some recomendations that will save me considerable money over time.
My experience with that company was fantastic!!
 
Holygral said:
My first RODI unit was a Ebay type of unit, it never did work right or get the tds below 7. After a year I bought the same unit that you are looking at from TFG and construction alone is a world apart. And the tds is 0: As far as the Rodi drinking water debate, you can just put in a couple valves (blue and white ones) to by pass the DI unit when you want to make drinking water. I make 5 gal at a time.
Click to expand...

could you snap a picture of your set up so i know what kind of valves your talking about, and placement? did the valves come with your package through TFG?
 
NWDiver said:
They have the RO bypass kit for drinking water on the webpage http://www.thefilterguys.biz/ro_di_add-ons.htm at the bottom.
I use the option, but I have not figured out how to auto stop the water for the 3 gal drinking jug without using a timer.
Click to expand...

One of the best ways to store RO water (and take advantage of the auto shut off) is to use a steel bladder tank.

The setup goes something like this:
http://apoon.com/images/aquarium/rodi-setup.jpg

You tap the RO water off before the DI...I forget the exact reason, but the DI water cannot be stored in the steel tank, something to do with causing corrosion I believe.
 
Thanks, I probably should do that setup. I think that you don't really want to drink the water after the DI anyway so that should work fine. Thanks for the idea!
 
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