Is RODI really more expensive?

[hilgert]

Having watched over the years (and with some amusement) many people lugging 5-gallon containers of RODI/saltwater out of fish stores, I thought I'd lay out some math on on the cost of RODI in the hopes that a few pocketbooks may benefit.

Assumptions:

• A decent new RODI (which INCLUDES an initial set of filters) is $170. Here is what I would get if I were buying a new system today:
  BRS 4 Stage Value PLUS RO/DI System - 75GPD
  Note that this INCLUDES the first set of filters and an inline TDS meter.
• RODI filters/cartridges last for about 1000 gallons of finished RODI water (mine last much longer, but just assuming 1000 gallons for this exercise).
• The cost for replacing sediment filter, carbon block and DI is about $40 per set (you can spend less or more).
• RO membrane (the real "heart" of the system) lasts for 5000 gallons of finished RODI (these can last MUCH longer if flush regularly...but assuming 5000 gallons this for this exercise).
• The cost of a new RO membrane is $50 (you can spend less or more).
• Excluding cost of tap water into the RODI (this can vary from practically nothing to a lot...for me it's something I don't care about).
• "Average" tap water conditions...some people may have much better tap water (RODI stuff will last longer), while others may have much worse tap water (RODI stuff will need replacing sooner).
• This is based on my experience using RODI at several places I've lived in the US (When I measured today my TDS was 383...I've seen it up to 450 and down to 280). For ME these numbers are conservative...I get a lot more mileage out of my RODI system than the assumptions I am making above.

Cost for the FIRST 5000 gallons of finished RODI water:

• RODI system - $170.
• Filter/cartridge replacements - $160 (4 replacements at $40 each).
• Total cost for 5000 gallons of RODI - $330
• Cost per gallon: $0.07 (rounding up).

Cost for the NEXT 5000 gallons of finished RODI water:

• Filter/cartridge replacement - $200 (5 replacements at $40 each).
• RO membrane replacement - $50.
• Total cost for 5000 gallons of RODI: $250.
• Cost per gallon: $0.05.

So, even if one were to double the cost of the system/filters ($340/$80), and halve the amount of RODI water produced (2500 gallons), that's still $0.27 (rounded up) and $0.20 respectively.

For smaller systems (nano tanks and the like) perhaps an RODI system would be overkill (a long payback period, or an unwanted use of space for a small system), and LFS store-bought RODI might be a better approach (but please, not tap water...I beg you). My opinion is that if you have a good water change schedule, and have a tank that is 50 gallons or larger, you would be well-served by owning your own RODI system rather than paying someone else 10X the cost (plus the fuel cost to/from the store).

So, what's really the cost of an RODI system? Almost free, relative to all the other expenses in this hobby (tanks, lights, pumps, fish, corals, rocks, leaks, fights with spouse, etc.). A nickel per gallon...and no fuel/time spent going to/from the LFS. Essentially, the annual cost (with the math above) is about the cost of one fish or coral (that proper water might save).

Ever wonder why almost no fish stores sell RODI systems, and why they are so happy to help you with your RODI water refills? I've actually had this discussion with some LFS owners over the years, and the answer is always "Why would I want to sell RODI systems when I can sell water at 10X what it costs me to make." Every time I see folks going in/out of LFS with jugs of water I picture the LFS owner laughing (that Dr. Evil laugh from Austin Powers).

 

[novadan67]

Around here the LFS's sell RODI very cheap (~$0.25/gal or less), one of them even gives it away for free as "customer appreciation". Their incentive is to get you in the store where you are very likely to buy something... Still the pain of lugging buckets or jugs makes having your own system worth the cost if your tank is very large...

 

[snorvich]

For convenience if for no other reason, producing your own RO/DI water is desirable. The thing missing from the above analysis is the actual TDS of RO/DI water you are buying. Is it always zero? I think not.

 

[ahmed_iAM]

Of coarse what is "worth it" will vary based on the individual. I find the convenience of my own system better. I also use it for drinking and if I want to dilute certain liquids.

Also cost depends on the water in your area. Harder water will force you to chance the membrane and filters multiple times a year if you have a large system. Use ~5 gallons a day and haven't replaced it in 6 months. Still reading 0.

 

[Jimmer12]

Is it simple to plumb a rodi unit to also have an ro output? I currently buy ro water for my water cooler and get it very cheaply at $.20/gallon and I am now planning to start a reef tank and was hoping to convince the wife that a rodi unit will save us money and the hassle of buying jugs of ro water for the cooler as well.

 

[Pife]

Is it simple to plumb a rodi unit to also have an ro output? I currently buy ro water for my water cooler and get it very cheaply at $.20/gallon and I am now planning to start a reef tank and was hoping to convince the wife that a rodi unit will save us money and the hassle of buying jugs of ro water for the cooler as well.

Just use the rodi water.


Great break down on costs. Thanks for taking the time to prove I made the right choice.

 

[hilgert]

Just use the rodi water.

Um, no...that could lead to serious health issues. The human body is not "built" to process RODI. Google "RODI water safe to drink" and you will see.

Small amounts will send you to the bathroom more often than you'd want, and large amounts are downright dangerous.

 

[Bent]

Your forgetting the cost of membrane replacements, filter media replacements, and DI replacements.

If your going to be doing this a while, I'd say that th RO/DI would pay itself off in whatever amount of water you would be paying for and lugging home, but it would take a lot longer than you would think.

 

[hilgert]

Is it simple to plumb a rodi unit to also have an ro output? I currently buy ro water for my water cooler and get it very cheaply at $.20/gallon and I am now planning to start a reef tank and was hoping to convince the wife that a rodi unit will save us money and the hassle of buying jugs of ro water for the cooler as well.

See my post just prior to this one with regard to using RO for drinking water (but do NOT use RODI). To me (my opinion) it's probably better to use the water just before the RO, as you won't have to store it, it will always be available, and it still has passed the sediment and carbon blocks.

That's just my opinion...but many folks tap off their RO into a holding tank. The issue for me is that the RO output is about 1/5 of normal output, as 4/5 of the water is going to waste (which is what an RO membrane does), so RO would just "dribble" out (hence the use of holding tanks). If I were to do this I'd always want water "now", and I'd be happy with filtered (before the RO) water.

But again, many folks do the post-RO tap.

Also, on the wife, don't forget to factor in the cost of something SHE will want at some point, when she says "Well, I let YOU buy YOUR RODI system".

 

[hilgert]

Your forgetting the cost of membrane replacements, filter media replacements, and DI replacements.

If your going to be doing this a while, I'd say that th RO/DI would pay itself off in whatever amount of water you would be paying for and lugging home, but it would take a lot longer than you would think.

Huh? Are you talking about my original post? I did factor all of those things in.

I think somewhere between 500 and 1000 gallons would be the payback point depending on what you can get water for, and that's not including fuel costs and medical expenses for back surgery from hauling around 40lb (5gal) containers.

 

[Bent]

Um, no...that could lead to serious health issues. The human body is not "built" to process RODI. Google "RODI water safe to drink" and you will see.

Small amounts will send you to the bathroom more often than you'd want, and large amounts are downright dangerous.

BS.

I have a whole home RO unit. We've been drinking it for years and no ones dead.

Edit: the only water which safety is questionable is distilled. Look THAT up. There are these things called medical journals.

 

[hilgert]

BS.

I have a whole home RO unit. We've been drinking it for years and no ones dead.

Edit: the only water which safety is questionable is distilled. Look THAT up. There are these things called medical journals.

I did not say RO was dangerous...I said RODI was dangerous. If you have a whole home RO system that is fine...as it's not RODI (emphasis on DI). It's the DI aspect...the water TOTALLY devoid of anything...that can cause imbalances in our body. Again, Google is your friend here...don't believe me...believe the experts: www.google.com/search?q=RODI+water+safe+to+drink

 

[disc1]

Um, no...that could lead to serious health issues. The human body is not "built" to process RODI. Google "RODI water safe to drink" and you will see.

Small amounts will send you to the bathroom more often than you'd want, and large amounts are downright dangerous.

This is what happens when people "sort of" understand science. The worst that can happen is that it pulls salt out of your spit. Then it isn't RODI anymore.

People seem to forget that once it does this horrible thing they think it does, pull salts out of other things, you're drinking it. So are you losing anything? No.

But your body needs minerals! Yes, and you get them from your food. Most of us aren't relying on our water for mineral content.

 

[snorvich]

Well RODI water does not taste very good to me (and my wife). We do drink RO water but not DI.

 

[ahmed_iAM]

Is it simple to plumb a rodi unit to also have an ro output? I currently buy ro water for my water cooler and get it very cheaply at $.20/gallon and I am now planning to start a reef tank and was hoping to convince the wife that a rodi unit will save us money and the hassle of buying jugs of ro water for the cooler as well.

I'd recommend against drinking RODI/DI. It removes that "mineral" taste and free floating ions. RO would be best for drinking, but drink tap water IF you have good water in your area. Recommend against tap if your in an urban area like New York.

 

[ChimolaFish]

I would say it's worth if for the convenience plus places around me charge something like 1.25 a gallon, which is obviously quite expensive. Also depends on how often and how large of water changes you do. I do something like 10 percent up to 25 percent weekly or bi-weekly. It's true having a filter isn't cheap, but the hobby isn't cheap and determining whether or not a personal system is worth it is up the individual

If you get the brs system that does 150 gallons per day, it saves money since it doesn't waste as much water.

 

[Jimmer12]

I'd recommend against drinking RODI/DI. It removes that "mineral" taste and free floating ions. RO would be best for drinking, but drink tap water IF you have good water in your area. Recommend against tap if your in an urban area like New York.

That's why I asked about plumbing an output after the ro stage. Our local water is awful, we regularly get drinking water warnings and some days you can smell the chlorine when you shower and feel it in your eyes. The place I use to fill our water cooler jugs told me the tap water regularly tests for TDS in excess of 600.

Ironically our local water is so hard and mineral rich that it make for incredible African cichlid tank. Those little guys just flourish with colour and growth in our tap water.

 

[Bent]

I did not say RO was dangerous...I said RODI was dangerous. If you have a whole home RO system that is fine...as it's not RODI (emphasis on DI). It's the DI aspect...the water TOTALLY devoid of anything...that can cause imbalances in our body. Again, Google is your friend here...don't believe me...believe the experts: www.google.com/search?q=RODI+water+safe+to+drink

Google means nothing. I can show you about a hundred articles pulled up by searching Dr. google that will tell you wholistic medicine is the answer and those pills prescribed to you are "poison."

Don't trust the "experts." Trust science.

If google doesn't give you something published by the AJM or some other reputable source that gives you links to case studies and evidence based research, then ignore it.

Example:
http://www.google.com/m?q=doctors are dangerous

 

[Bent]

This is what happens when people "sort of" understand science. The worst that can happen is that it pulls salt out of your spit. Then it isn't RODI anymore.

People seem to forget that once it does this horrible thing they think it does, pull salts out of other things, you're drinking it. So are you losing anything? No.

But your body needs minerals! Yes, and you get them from your food. Most of us aren't relying on our water for mineral content.

Thank you.

 

[Kyle918]

One time of lugging two five gallon jugs up stairs to my apartment was enough for me. I bought a 4 stage and haven't looked bad.

It is simple to plumb it for RO. Just T the line before the DI stage... I have a valve in that line as well.

RO/DI isn't deadly, it's just lacking minerals. Don't need google to tell me that. I'm pretty sure zero TDS tells enough of that story. Most people also don't rely on water solely for their mineral intake. Several people don't even drink a glass of water a day so what's the big deal? Some water is better than none but I personally use the RO for drinking.