DI water filters. That's right no RO

BRS

[email protected]

New Member
View Badges
Joined
Jul 5, 2018
Messages
1
Reaction score
0
Review score
+0 /0 /-0
I once read a post about the use of DI only filters. The person was saying that you actually save money by filtering with on a DI chamber vs using a RO prefilter. The only problem is that I lost the thread right after it got started. Has anybody heard of this concept? Below are a few points that I remember.
Reasoning behind this was that you won't be replacing RO filters or producing any waste water.

The only downfall is replacing the DI media, but that can be purchased in bulk.

Any feedback?
 

Lowell Lemon

2500 Club Member
View Badges
Joined
May 23, 2015
Messages
2,778
Reaction score
11,609
Review score
+0 /0 /-0
Location
Washington State
I once read a post about the use of DI only filters. The person was saying that you actually save money by filtering with on a DI chamber vs using a RO prefilter. The only problem is that I lost the thread right after it got started. Has anybody heard of this concept? Below are a few points that I remember.
Reasoning behind this was that you won't be replacing RO filters or producing any waste water.

The only downfall is replacing the DI media, but that can be purchased in bulk.

Any feedback?

You might look into rental units from Culligan. I used to maintain aquariums as part of my business and the portabile nature of the DI cylindar worked great. Seems like it was less than $15.00 per month with a $50,00 recharge of the resin. I would recharge about twice a year. I could process hundreds of gallons in a short time span for water changes. It worked for great saltwater reefs and freshwater. Cost less per gallon with less waste water.
 

Bruno516

Active Member
View Badges
Joined
Apr 13, 2018
Messages
127
Reaction score
246
Review score
+0 /0 /-0
Its more beneficial to get an RODI unit and buy bags of bulk resin and change them out when need be. Spectrapure carries a 5L bag that will fill up 6 10" DI canisters ($8 a fill) and you can get a good lifespan out of them. Just make sure you have a TDS meter
 
BRS

Opus

2500 Club Member
View Badges
Joined
Aug 29, 2011
Messages
3,556
Reaction score
2,147
Review score
+0 /0 /-0
Location
North Texas
I don't see how that would be possible. My RO water before DI is around 3 tds, so I will get around 1500 gallons of 0 tds water from a DI cartridge. My tap is around 400 tds. If I ran that thru a DI cartridge, I would only get about 11 gallons of 0 tds water and then it would need to be replaced. So even if you have really good tap water, say 50 tds, you would only get around 90 gallons of 0 tds water out of a DI catridge.
 

PEP12

Active Member
View Badges
Joined
Jan 27, 2017
Messages
112
Reaction score
93
Review score
+0 /0 /-0
Its more beneficial to get an RODI unit and buy bags of bulk resin and change them out when need be. Spectrapure carries a 5L bag that will fill up 6 10" DI canisters ($8 a fill) and you can get a good lifespan out of them. Just make sure you have a TDS meter
 

SashimiTurtle

Turtle
View Badges
Joined
Feb 24, 2017
Messages
8,888
Reaction score
33,607
Review score
+0 /0 /-0
Location
South Carolina
I don't see how that would be possible. My RO water before DI is around 3 tds, so I will get around 1500 gallons of 0 tds water from a DI cartridge. My tap is around 400 tds. If I ran that thru a DI cartridge, I would only get about 11 gallons of 0 tds water and then it would need to be replaced. So even if you have really good tap water, say 50 tds, you would only get around 90 gallons of 0 tds water out of a DI catridge.

Agreed... my tap is 80-90 tds and RO puts out 0-1 tds. I get very long life out of DI resin (6+months) but if I were to bypass my RO I could only do a few water changes on my 90g reef before Im changing my DI out.

Water is cheap here, my bill is around $20-30 a month. Replacing $10 in DI resin a month to reduce my water bill by maybe a dollar doesn't seem cost effective to me.
 

chipmunkofdoom2

Always Making Something
View Badges
Joined
Jun 6, 2017
Messages
2,267
Reaction score
4,206
Review score
+0 /0 /-0
Location
Baltimore, MD
You will find it very hard to beat RO + DI with just DI. People often complain about the waste water and replacing RO membranes, but these costs are relatively low, even if you count prefilters, which most people don't.

Sources may vary, but generally tap water is reported to cost roughly $0.004 cents per gallon in the US. If you run a waste to product ratio of 4 : 1, that means it takes 5 gallons of water total to make one gallon of filtered water. Most people actually run ratios much lower than this, so the actual usage of most reefers is probably around half of this, but this is a decent place to start. Let's say you use 100 gallons of RO/DI a month. That's two 25 gallon water changes and 50 gallons of topoff, which is about 1.67 gallons of evaporation a day. If you made 100 gallons of RO/DI at $0.004 per gallon, that 100 gallons of fresh water would only cost you $2, even after you factor in all the waste water. That's roughly two pennies per gallon. If your water is twice as expensive as the national average, you're still only paying $4 per month for your water. Even if you pay five times the average cost of tap water in the US, your monthly aquarium water bill would still only be $10. That's still only a dime a gallon, and that's at 5 times the national average price.

Sure, you have to replace your RO membrane every three years or so (although I got 10 years out of my last membrane by treating it well and replacing prefilters often). Still, at a cost of $35, that's only costing you $0.97 per month. So instead of your water costing you $2/100 gallons per month, it now costs $2.97/100 gallons per month. Even if you add in prefilters, which might cost $30 annually, that's only $2.50 extra per month. We're still only at around $6 for 100 gallons of RO/DI, or just over a nickel per gallon.

The above analysis doesn't factor in DI resin costs because those are hard to quantify, but still, paying barely more than a nickel per gallon of RO water is not a bad deal. You'd have to have some exceptionally pure tap water for DI alone to meet these kinds of costs per gallon. Either that, or you'd have to know someone in the business and get your resin for very cheap.
 

Bruno516

Active Member
View Badges
Joined
Apr 13, 2018
Messages
127
Reaction score
246
Review score
+0 /0 /-0
You will find it very hard to beat RO + DI with just DI. People often complain about the waste water and replacing RO membranes, but these costs are relatively low, even if you count prefilters, which most people don't.

Sources may vary, but generally tap water is reported to cost roughly $0.004 cents per gallon in the US. If you run a waste to product ratio of 4 : 1, that means it takes 5 gallons of water total to make one gallon of filtered water. Most people actually run ratios much lower than this, so the actual usage of most reefers is probably around half of this, but this is a decent place to start. Let's say you use 100 gallons of RO/DI a month. That's two 25 gallon water changes and 50 gallons of topoff, which is about 1.67 gallons of evaporation a day. If you made 100 gallons of RO/DI at $0.004 per gallon, that 100 gallons of fresh water would only cost you $2, even after you factor in all the waste water. That's roughly two pennies per gallon. If your water is twice as expensive as the national average, you're still only paying $4 per month for your water. Even if you pay five times the average cost of tap water in the US, your monthly aquarium water bill would still only be $10. That's still only a dime a gallon, and that's at 5 times the national average price.

Sure, you have to replace your RO membrane every three years or so (although I got 10 years out of my last membrane by treating it well and replacing prefilters often). Still, at a cost of $35, that's only costing you $0.97 per month. So instead of your water costing you $2/100 gallons per month, it now costs $2.97/100 gallons per month. Even if you add in prefilters, which might cost $30 annually, that's only $2.50 extra per month. We're still only at around $6 for 100 gallons of RO/DI, or just over a nickel per gallon.

The above analysis doesn't factor in DI resin costs because those are hard to quantify, but still, paying barely more than a nickel per gallon of RO water is not a bad deal. You'd have to have some exceptionally pure tap water for DI alone to meet these kinds of costs per gallon. Either that, or you'd have to know someone in the business and get your resin for very cheap.

Great info! I'm going to be using this on all my service calls. Spectrapure makes high quality systems with ultra low ratios (1:1) and customers in California LOVE that due to the fact that water cost so much there!
 
BRS

Peter Clark

Active Member
View Badges
Joined
Apr 18, 2018
Messages
151
Reaction score
258
Review score
+0 /0 /-0
Location
Wilmette, IL
In college I had an DI only thing I would just connect to the kitchen sink and feed a large 50g bin used for ATO water. I didn't have the space for a full RODI system and honestly couldn't afford the full setup. I didn't keep SPS so I was technically fine just using treated tap water, but I upgraded to DI to be safe. Only ran it for about a year before graduation. Worked well as far as I could tell, but I also didn't have a clue what I was doing and didn't have a TDS meter. I now have a RODI system in my basement.
 

redfishbluefish

Stay Positive, Stay Productive
View Badges
Joined
Mar 22, 2012
Messages
10,756
Reaction score
21,423
Review score
+0 /0 /-0
Location
Sayreville, NJ
A number of years ago (maybe 8 - 10 years ago) I knew a number of reefers who used a system of DI only called Kati-Ani. They were large canisters of individual resins. When the resin was spent, you'd simply replace the liquid in the resin with either sodium hydroxide or hydrochloric acid solutions (in the respective resin), and let them sit for an hour and then rinse. Respective resins would be re-generated and set to go again. So yes, it can be done.

This isn't a very good video, but the only one I could find showing the canisters. They also came in larger sizes.

 

saltyhog

blowing bubbles somewhere
View Badges
Joined
Jan 2, 2014
Messages
8,758
Reaction score
23,327
Review score
+0 /0 /-0
Location
Conway, Arkansas
Wouldn't be very cost effective for me. My water bill is less than $25 most months(when summer watering is not going on) and the TDS of my tap water is 35-40. My post RO water is usually zero but occasionally 1. My RO membrane is 5 1/2 years old and still going strong.
 
Top Shelf Aquatics

Lowell Lemon

2500 Club Member
View Badges
Joined
May 23, 2015
Messages
2,778
Reaction score
11,609
Review score
+0 /0 /-0
Location
Washington State
A number of years ago (maybe 8 - 10 years ago) I knew a number of reefers who used a system of DI only called Kati-Ani. They were large canisters of individual resins. When the resin was spent, you'd simply replace the liquid in the resin with either sodium hydroxide or hydrochloric acid solutions (in the respective resin), and let them sit for an hour and then rinse. Respective resins would be re-generated and set to go again. So yes, it can be done.

This isn't a very good video, but the only one I could find showing the canisters. They also came in larger sizes.


I had one of the Kati Ani units years ago and did my own recharge. Boy does that take me back lol.
 

mcarroll

10K Club member
View Badges
Joined
Jan 8, 2012
Messages
13,795
Reaction score
7,866
Review score
+0 /0 /-0
Location
Virginia
I used the medium one about 30" tall. Not to bad at all...even full.

Seems like around (15 a month + 50 per fill =) $200+ a year is quite a bit vs RODI.

I'll grant you the speed difference – making clean water at tap-water speeds is nice when you need it. ;)

And a DI system that will do that rate costs A LOT less than an RODI that will even get close.

I'm not sure it's fair to compare RODI to DI on cost though.

RODI is way cheaper under "normal" conditions and the float valve+offline storage is the traditional answer for the slow production rates. ;)

I'm guessing that DI-only could make sense if you're getting paid to take care of the tank in question....speed might be more important than the last nickel.

(Around here the last nickel gets it. :D)
 

Tristren

Well-Known Member
View Badges
Joined
May 16, 2017
Messages
786
Reaction score
805
Review score
+0 /0 /-0
Location
Ottawa
This seems like it would be interesting from an environmental/wastewater perspective. I'm surprised to see so many Californians talking about how cheap water is given the ongoing drought issues. Is that something that people think will change?

Tony
 

Randy Holmes-Farley

Reef Chemist
View Badges
Joined
Sep 5, 2014
Messages
44,831
Reaction score
33,714
Review score
+0 /0 /-0
Location
Arlington, Massachusetts, United States
This seems like it would be interesting from an environmental/wastewater perspective. I'm surprised to see so many Californians talking about how cheap water is given the ongoing drought issues. Is that something that people think will change?

Tony

The cost of DI alone in some places in california, where water has pretty high TDS, is very high. An RO/DI might knock down DI usage by a factor of 10-50.

As an issue of pure impact on the planet, one should not ignore the cost (energy, water, etc.) of producing and/or recharging the DI resins
 

Tristren

Well-Known Member
View Badges
Joined
May 16, 2017
Messages
786
Reaction score
805
Review score
+0 /0 /-0
Location
Ottawa
The cost of DI alone in some places in california, where water has pretty high TDS, is very high. An RO/DI might knock down DI usage by a factor of 10-50.

As an issue of pure impact on the planet, one should not ignore the cost (energy, water, etc.) of producing and/or recharging the DI resins
That’s interesting. As always the answer is “it’s complicated” I suppose.

It occurs to me that not only do I not know what’s involved in creating DI resins, I don’t actually know what they are (aside from a bunch of beads in a bag.

Is there a way of calculating how much DI you would use based on TDS?

My TDS out of the tap here in Ottawa is 50. We also don’t have much in terms of water shortages. So trying to figure out what makes sense. In the meantime I got a second RO filter and a booster pump to try and reduce waste/increase efficiency that way. (As you point out, factoring in the production and shipping impact of those elements could also undercut the value from a footprint perspective…)

Tony
 
https://www.youtube.com/c/ReefStache
BRS

What's the main reason you take on DIY reefing projects?

  • Save Money

    Votes: 109 34.7%
  • You Like To Make Things

    Votes: 111 35.4%
  • Necessity, you want it a certain way

    Votes: 78 24.8%
  • Time, you need it quick

    Votes: 5 1.6%
  • Other (please explain)

    Votes: 11 3.5%
Queen City Corals
Top