High volume AND High TDS RO/DI issues

Herpervet · 10/10/2006, 08:45 PM

I use about 60 gallons of ro/di water every 3 to 5 days due to high evaporation rate on my large system.

The tap water tds is very high out here and ranges from 400 to over 500.

I am running two 75gpd filmtec membranes in a cascading fashion so that the waste from the first membrane feeds the second membrane. I also have a booster pump to take the pressure to around 80 psi.

Generally I get around 20tds water out of the ro effluent.

I have tried three different di cartriges. Mixed bed resins from two sources (both highly regarded sources) and spectrapure maxcap cartridge followed by a combination of 1/3 canister anion resin then mixed bed resin.

This worked better but still I am only getting a couple of months before I need to change out both the max cap cartrige and the second combination (ani/mixed bed) also.

Recently a friend told me about a cati/ani system from germany that is touted as having by far superior results.

The vendor claims that some fairly highly regarded folks here on reefcentral use this system.

I am curious if this is simply one of those "euro is better" (and really expensive) situations or if there really is a "lab grade" resin that is hands down better than the standard resins we get in the hobby.

From a chemistry stand point it seems to me that the function of these resins should be proportional to the surface area first then the affinity to the ions it is pulling out so I am having a difficult time wrapping my mind around the idea that the german resins could be that much better.

thanks,

Pete

Billybeau1 · 10/10/2006, 09:45 PM

Unique situation. I summoned someone who may be able to help. Hang tight. If not tonight, you'll get an answer in the am.

Boomer · 10/10/2006, 10:00 PM

Your issue is CO2 which depletes the DI. It would be best to run a water softener before the RO/DI.

The vendor claims that some fairly highly regarded folks here on reefcentral use this system.

Where and what are these resins. I think it is nonsense and a sells pitch. There are however Nuclear grade resins. And I think that is what the Spectro-'s are IIRC.

From a chemistry stand point it seems to me that the function of these resins should be proportional to the surface area first then the affinity to the ions

That is correct Pete

Herpervet · 10/10/2006, 10:36 PM

Boomer,

Actually I forgot to meniton I do run a small softener as the first stage.

Explain the C02 issue for me. How does C02 correlate with TDS? I do recall that contact with air will deplete the resin so that makes some sense.

The vendor claims that Stephen Pro uses his system and is very happy with it. I have e-mailed Stephen already.

He also mentioned Anthony Calfo's name.

The next question is what to do next so that I don't have to change resin so often. Once per 6 to 8 months would be much more managable, not to mention the cost.

Boomer · 10/10/2006, 10:56 PM

Pete

How does C02 correlate with TDS?

It has nothing to do with being exposed to air. High TDS water is often very high in CO2 and CO2 goes right through the RO. The CO2 combines with water on the output of the RO to form carbonic acid, H2CO3, which dissociates in water to form HCO3- and CO3--. These ionic species will contribute to the total anionic load and deplete the DI. This HCO3- and CO3-- will raise the TDS on the output of the RO.

CO2(g) + H20==> H2CO3 ==> H+ + HCO3- ==> 2H+ + CO3--

Reverse Osmosis/Deionization Systems to Purify Tap Water for Reef Aquaria
http://reefkeeping.com/issues/2005-05/rhf/index.htm

Herpervet · 10/10/2006, 10:59 PM

Thanks Boomer,

Do you have an opinion on what I can do to improve the system?

If I had a little more room I would run an airstone in a second resovoir and plumb that tank to my ro/di and run with the booster pump.

My fish room is getting cramped however. I guess I am looking at adding 2 or 3 more canisters of mixed bed resin?

Boomer · 10/10/2006, 11:03 PM

Not off hand Pete. Usually a good WS solves the issue. Take a read through Randy's artlice and see if anything else is there.

I also added this to the above post

This HCO3- and CO3-- will raise the TDS on the output of the RO.

Jim is here so maybe he can help you

The filterguys

Boomer · 10/10/2006, 11:16 PM

I might add there are some new high-tech membrane EDI/CDI untis which have little CO2 issue.

Look for links to Liqui-Cel Membrane Contactors

http://www.liqui-cel.com/applications/CO2.cfm

Thefilterguys · 10/10/2006, 11:23 PM

Pete you are going to get nothing better out of a cati/ani system then what you getting from a mixed bed resin. The guys using cati/ani systems don't use RO and get very low production before they have to regenerate the resin. Regeneration uses hazardous chemicals and is a lot of work.

If you water chemistry was perfect you can expect 7500 ppm of TDS absorption per DI cartridge. With an RO tds of 20 it would give you 375 gallons of production water. If as Boomer suggests CO2 is an issue then all bets are off and your production will be very limited.

Jim

Boomer · 10/10/2006, 11:25 PM

Jim see new post above

Thefilterguys · 10/10/2006, 11:26 PM

You really need to give us some production figures so we know how your different resins have performed. You may already be at the peak of resin performance.

Jim

Herpervet · 10/10/2006, 11:38 PM

Jim,

I'm sorry but I really havn't kept track of production numbers.

It's a very rough estimate but I think the max-cap cartirges were exhausted after about 350-400 gallons at which time the second stage gets rapidly depleted.

I'm sorry but I can't give you very accurate data.

I might try stripping the CO2 using one of the membranes from the link boomer provided but from looking at the site I suspect they are $$$.

I am thinking that simpler might be better however and I might just add 3 or 4 more mixed bed cartriges.

One other idea: Could I run through 1 filmtec membrane then feed the second membrane with the permeate from the first? Even if this required a second booster pump it might solve my problem right?

i.e. drop the TDS to 20 then down to 2 to 4 from the second pass?

If I did the above with 3 membranes: i.e. cascading membranes with the effluent side going to a third membrane. This wouldn't waste as much water right?

Sorry, I'm grasping at straws since the resin costs and constant hassle are frustrating.

Thefilterguys · 10/11/2006, 12:03 AM

Pete interesting with all the hype the maxcap doesn't seem to live up to the claims.

Boomer the stripper is interesting but with no pricing I also suspect big bucks but I'm sure you'll have pricing for us. If the price were right a lot of people with well water would be lining up for this.

Pete I took a look at you municipal water report but it is very limited with information.

I'm not sure if a second booster pump could perform that task Pete. If CO2 is an issue you could bubble off the CO2 from your RO water and then pass it through your DI but you still have that 20 TDS. Really you should be getting better TDS from your membranes I cant remember if you added the Aquatec auto flush valve?

Jim

Steven Pro · 10/11/2006, 04:27 AM

I do use an Aquatechnik Kati-Ani unit (as does Anthony), but I don't think the resins are that much superior to anything one can buy from someone like SpectraPure. The big difference is the Kati-Ani is rechargeable and the recharging chemicals are dirt cheap in comparison to the disposable, mixed resin bed DI cartridges that come with RO/DI units.

Looking at your numbers, 400-500 TDS coming into the RO with 20 coming out, that would mean your membranes are rejecting 95-96%, if I did the math right, which seems normal. I would continue to use the RO, but would consider adding a Kati-Ani in place of the disposable, mixed resin cartridges. You would probably start saving money after about a year depending on the cost of the mixed resin cartridges and what size Kati-Ani you get.

The big question that you must ask yourself before purchasing is, are you comfortable doing the recharge? I have been using a Kati-Ani for over 8 years and am very comfortable doing the recharge. But, you must answer that question yourself.

Steven Pro · 10/11/2006, 04:48 AM

Quote:

Originally posted by Thefilterguys
Pete you are going to get nothing better out of a cati/ani system then what you getting from a mixed bed resin. The guys using cati/ani systems don't use RO and get very low production before they have to regenerate the resin. Regeneration uses hazardous chemicals and is a lot of work.

The Kati-Ani can operate at up to 10 gallons per hour or 240 gpd in RO terms. My old #2 unit would produce 200-500 gallons of water (it varied seasonally) before needing recharged, which was about 4-6 months of use with my old 55. I upgrade to a #10 set in April of this year, have gotten well over 1,000 gallons out of it (I really can't recall exactly), and it is now due for its first recharge. Recharging the unit is a breeze.

It takes about 5 minutes of work to mix the chemicals and set it up. I then go play with my kids or watch some TV, come back a while later, and it is done and just needs flushed out.

The chemicals though, NaOH and HCl, can be dangerous in the hands of someone inexperienced. But, they are common chemicals that you can buy most anywhere. The HCl is sold at hardware stores for etching concrete. The NaOH is a common drain cleaner. The companies that make and sell these items obviously feel they are safe enough for your average Joe to throw on their driveways or pour down their sink.

Randy Holmes-Farley · 10/11/2006, 06:40 AM

I agree that recharging is a potential advantage for some folks, but it is not something that I'd choose for myself.

FWIW, all issues about the high "purity" of the DI resin are gone once you recharge with ordinary chemicals available to DIY'ers. I also do not consider high purity important for reef aquaria at all.

I detail how RO/DI system work here:

Reverse Osmosis/Deionization Systems to Purify Tap Water for Reef Aquaria
http://reefkeeping.com/issues/2005-05/rhf/index.htm

Thefilterguys · 10/11/2006, 08:45 AM

Quote:

Originally posted by Steven Pro
The Kati-Ani can operate at up to 10 gallons per hour or 240 gpd in RO terms. My old #2 unit would produce 200-500 gallons of water (it varied seasonally) before needing recharged, which was about 4-6 months of use with my old 55. I upgrade to a #10 set in April of this year, have gotten well over 1,000 gallons out of it (I really can't recall exactly), and it is now due for its first recharge. Recharging the unit is a breeze.

It takes about 5 minutes of work to mix the chemicals and set it up. I then go play with my kids or watch some TV, come back a while later, and it is done and just needs flushed out.

The chemicals though, NaOH and HCl, can be dangerous in the hands of someone inexperienced. But, they are common chemicals that you can buy most anywhere. The HCl is sold at hardware stores for etching concrete. The NaOH is a common drain cleaner. The companies that make and sell these items obviously feel they are safe enough for your average Joe to throw on their driveways or pour down their sink.

Steve Are you running RO or just the cati/ani system? What is your TDS going into your housings and how large are your DI housings? Most people I have talked to say they get very low yield but they are trying this with high TDS. You are the first I have seen with good results. A little more explanation on regenerating would be good since you have years of experience? Do you experience one resin exhausting more rapidly then the other?

Jim

Thefilterguys · 10/11/2006, 08:55 AM

Quote:

Originally posted by Thefilterguys
Pete you are going to get nothing better out of a cati/ani system then what you getting from a mixed bed resin. The guys using cati/ani systems don't use RO and get very low production before they have to regenerate the resin. Regeneration uses hazardous chemicals and is a lot of work.

Steve don't take my comments wrong but you are the first person reporting really good results. The darkside I painted are from all reports I have had up to this time hopefully you are painting a brighter picture.

Jim

Steven Pro · 10/11/2006, 09:00 AM

I do not run RO, just the DI. Although, I did add a common household water filter before the Kati-Ani and use a 0.5 micron carbon block filter in there.

The #2 set I had was approximately 2.5" in diameter and 24" tall. My new #10 set is about 6" in diameter and 36" tall, so these are significantly larger than the standard 10" mixed resin bed cartridges available. I have heard of people getting low yields with DI-only unit's made by Aquarium Pharmaceuticals and Kent, but as I recall, both are rather small.

I don't have a TDS meter. Actually, I did just get one, but have yet to open up the box and use it. I just recharge them when about 3/4ths of the color changes.

Regenerating is fairly easy. You dilute the chemicals and allow them to drip through each half of the Kati-Ani for about 30 minutes, similar to setting up a kalkwasser drip. Then just flush them out and they are ready to go.

Steven Pro · 10/11/2006, 09:03 AM

Quote:

Originally posted by Thefilterguys
Steve don't take my comments wrong but you are the first person reporting really good results. The darkside I painted are from all reports I have had up to this time hopefully you are painting a brighter picture.

Jim

No problem. Kati-Ani units have never been real popular or widely available. Most people with experience with DI-only units are using small Aquarium Pharmaceuticals or Kent units and are not happy with them. They seem to taint the discussion.

Thefilterguys · 10/11/2006, 11:08 AM

OK that clears some things up and your right about small housings, most are using 10" cartridges. The last person I questioned, after flushing was only getting forty gallons of pure water with 10" cartridges per regeneration. One resin would last three times as long as the other. Regeneration is done out side of the housings and cartridge correct?

You never did give us you tap water TDS do you know?

Jim

Steven Pro · 10/11/2006, 11:32 AM

Quote:

Regeneration is done out side of the housings and cartridge correct?

No, not with the Kati-Ani. You regenerate inside the unit.

Quote:

You never did give us you tap water TDS do you know?

I just checked it and it was 280.

rick rottet · 10/11/2006, 12:44 PM

I also use the Aquatechnics Kati/Ani. (not that I'm a "highly regarded folk")

Tap water TDS = 680 - 760

I am using the same series 10 as Steven. I can get less than 300 gallons at -0- TDS when running straight tap water. By 350 gallons, the TDS would read higher the tap water (which I don't understand how that is possible, but thats what the monitors read). The series 10 is advertised to be able to process 9,800 gallons of "very hard" water before needing recharged.

After I installed (4) 100 GPD RO membranes before the DI set, the TDS exiting the RO was around 8 and I could run about 6,000 gallons of RO product water throught the DI before the TDS reading would creep up to 2. BUT, there would have been 18,000 to 24,000 gallons of water wasted, plus the iron level in my tap water would plug and clog the membranes in that same two months.

I installed an aspirating iron removal system (Marlo, Inc.). Tap water TDS is still around 580 - 620 after the iron removal system, but no more membrane troubles in about a year. I can still get about 6,000 gallons between recharges of the DI, maybe could get more, but I like to recharge when it goes from -0- to 2.

I would like to say, I agree with Steven. Recharging the units is fairly simple. Fill a big plastic container with water and the chemical (muriatic acid for the kati, sodium hydroxide for the ani) and let it siphon through the DI units, then rinse them through when the recharge is done.

honeybee · 10/11/2006, 02:45 PM

I too am using the Aquatechnics Kati/Ani units. I use rain water stored in a concrete cistern. The TDS is about 40 but I started with the resin columns because of high nitrates and phosphates. I now run the cistern water through a Pur-FloII with booster pump which reduces the 40TDS to 1TDS I expect the #2 column will last a long time. I will recharge when the Kat column is down 80%. I like the idea of reusing the resin rather than filling the land fill with DI cartiages.

Honeybee

Boomer · 10/11/2006, 03:58 PM

rick

Couple of quick ones ?

1. What is the vol. ratio of water to HCL in the container ?

2. Vol of sodium hydroxide to water ?

3. What do you mean by siphon or do you mean just let the cartridge fill and then let the water run out.?

4. Shouldn't there be a time constraint, as in x min in container ?

10/10/2006, 10:00 PM	#3
Boomer Bomb Technician (EOD) Join Date: Aug 2002 Location: Duluth, Minnesota Posts: 11,842	Your issue is CO2 which depletes the DI. It would be best to run a water softener before the RO/DI. The vendor claims that some fairly highly regarded folks here on reefcentral use this system. Where and what are these resins. I think it is nonsense and a sells pitch. There are however Nuclear grade resins. And I think that is what the Spectro-'s are IIRC. From a chemistry stand point it seems to me that the function of these resins should be proportional to the surface area first then the affinity to the ions That is correct Pete __________________ If you See Me Running You Better Catch-Up Seawater Chemistry, Geology, ID Marine Life, Collecting Science Books, Explosives Technology, Audiophile An explosion can be defined as a loud noise, accompanied by the sudden going away of things, from a place where they use to be.

10/10/2006, 10:56 PM	#5
Boomer Bomb Technician (EOD) Join Date: Aug 2002 Location: Duluth, Minnesota Posts: 11,842	Pete How does C02 correlate with TDS? It has nothing to do with being exposed to air. High TDS water is often very high in CO2 and CO2 goes right through the RO. The CO2 combines with water on the output of the RO to form carbonic acid, H2CO3, which dissociates in water to form HCO3- and CO3--. These ionic species will contribute to the total anionic load and deplete the DI. This HCO3- and CO3-- will raise the TDS on the output of the RO. CO2(g) + H20==> H2CO3 ==> H+ + HCO3- ==> 2H+ + CO3-- Reverse Osmosis/Deionization Systems to Purify Tap Water for Reef Aquaria http://reefkeeping.com/issues/2005-05/rhf/index.htm __________________ If you See Me Running You Better Catch-Up Seawater Chemistry, Geology, ID Marine Life, Collecting Science Books, Explosives Technology, Audiophile An explosion can be defined as a loud noise, accompanied by the sudden going away of things, from a place where they use to be.

10/10/2006, 11:03 PM	#7
Boomer Bomb Technician (EOD) Join Date: Aug 2002 Location: Duluth, Minnesota Posts: 11,842	Not off hand Pete. Usually a good WS solves the issue. Take a read through Randy's artlice and see if anything else is there. I also added this to the above post This HCO3- and CO3-- will raise the TDS on the output of the RO. Jim is here so maybe he can help you The filterguys __________________ If you See Me Running You Better Catch-Up Seawater Chemistry, Geology, ID Marine Life, Collecting Science Books, Explosives Technology, Audiophile An explosion can be defined as a loud noise, accompanied by the sudden going away of things, from a place where they use to be.

10/10/2006, 11:16 PM	#8
Boomer Bomb Technician (EOD) Join Date: Aug 2002 Location: Duluth, Minnesota Posts: 11,842	I might add there are some new high-tech membrane EDI/CDI untis which have little CO2 issue. Look for links to Liqui-Cel Membrane Contactors http://www.liqui-cel.com/applications/CO2.cfm __________________ If you See Me Running You Better Catch-Up Seawater Chemistry, Geology, ID Marine Life, Collecting Science Books, Explosives Technology, Audiophile An explosion can be defined as a loud noise, accompanied by the sudden going away of things, from a place where they use to be.

10/10/2006, 11:23 PM	#9
Thefilterguys RC Sponsor Join Date: Aug 2006 Location: Duluth, Mn Posts: 553	Pete you are going to get nothing better out of a cati/ani system then what you getting from a mixed bed resin. The guys using cati/ani systems don't use RO and get very low production before they have to regenerate the resin. Regeneration uses hazardous chemicals and is a lot of work. If you water chemistry was perfect you can expect 7500 ppm of TDS absorption per DI cartridge. With an RO tds of 20 it would give you 375 gallons of production water. If as Boomer suggests CO2 is an issue then all bets are off and your production will be very limited. Jim __________________ RO/DI Supplies & parts www.thefilterguys.biz We Custom Build Each System Phone 218 724-8000 Current Tank Info: 40 OCEANIC STRETCH HEX FRESH HEAVY PLANTED, 58 OCEANIC LPS, Monti’s ,Softy’s, 18 Nano Zoo’s , 11 Nano, 70 OCEANIC SPS New 200 Cube on the way

10/10/2006, 08:45 PM	#1
Herpervet Registered Member Join Date: Feb 2003 Posts: 675	High volume AND High TDS RO/DI issues I use about 60 gallons of ro/di water every 3 to 5 days due to high evaporation rate on my large system. The tap water tds is very high out here and ranges from 400 to over 500. I am running two 75gpd filmtec membranes in a cascading fashion so that the waste from the first membrane feeds the second membrane. I also have a booster pump to take the pressure to around 80 psi. Generally I get around 20tds water out of the ro effluent. I have tried three different di cartriges. Mixed bed resins from two sources (both highly regarded sources) and spectrapure maxcap cartridge followed by a combination of 1/3 canister anion resin then mixed bed resin. This worked better but still I am only getting a couple of months before I need to change out both the max cap cartrige and the second combination (ani/mixed bed) also. Recently a friend told me about a cati/ani system from germany that is touted as having by far superior results. The vendor claims that some fairly highly regarded folks here on reefcentral use this system. I am curious if this is simply one of those "euro is better" (and really expensive) situations or if there really is a "lab grade" resin that is hands down better than the standard resins we get in the hobby. From a chemistry stand point it seems to me that the function of these resins should be proportional to the surface area first then the affinity to the ions it is pulling out so I am having a difficult time wrapping my mind around the idea that the german resins could be that much better. thanks, Pete

10/10/2006, 09:45 PM	#2
Billybeau1 Registered Member Join Date: Jul 2005 Location: Dyer, Indiana Posts: 12,010	Unique situation. I summoned someone who may be able to help. Hang tight. If not tonight, you'll get an answer in the am.

10/10/2006, 10:36 PM	#4
Herpervet Registered Member Join Date: Feb 2003 Posts: 675	Boomer, Actually I forgot to meniton I do run a small softener as the first stage. Explain the C02 issue for me. How does C02 correlate with TDS? I do recall that contact with air will deplete the resin so that makes some sense. The vendor claims that Stephen Pro uses his system and is very happy with it. I have e-mailed Stephen already. He also mentioned Anthony Calfo's name. The next question is what to do next so that I don't have to change resin so often. Once per 6 to 8 months would be much more managable, not to mention the cost.

10/10/2006, 10:59 PM	#6
Herpervet Registered Member Join Date: Feb 2003 Posts: 675	Thanks Boomer, Do you have an opinion on what I can do to improve the system? If I had a little more room I would run an airstone in a second resovoir and plumb that tank to my ro/di and run with the booster pump. My fish room is getting cramped however. I guess I am looking at adding 2 or 3 more canisters of mixed bed resin?

10/10/2006, 11:25 PM	#10
Boomer Bomb Technician (EOD) Join Date: Aug 2002 Location: Duluth, Minnesota Posts: 11,842	Jim see new post above __________________ If you See Me Running You Better Catch-Up Seawater Chemistry, Geology, ID Marine Life, Collecting Science Books, Explosives Technology, Audiophile An explosion can be defined as a loud noise, accompanied by the sudden going away of things, from a place where they use to be.

10/10/2006, 11:26 PM	#11
Thefilterguys RC Sponsor Join Date: Aug 2006 Location: Duluth, Mn Posts: 553	You really need to give us some production figures so we know how your different resins have performed. You may already be at the peak of resin performance. Jim __________________ RO/DI Supplies & parts www.thefilterguys.biz We Custom Build Each System Phone 218 724-8000 Current Tank Info: 40 OCEANIC STRETCH HEX FRESH HEAVY PLANTED, 58 OCEANIC LPS, Monti’s ,Softy’s, 18 Nano Zoo’s , 11 Nano, 70 OCEANIC SPS New 200 Cube on the way

10/10/2006, 11:38 PM	#12
Herpervet Registered Member Join Date: Feb 2003 Posts: 675	Jim, I'm sorry but I really havn't kept track of production numbers. It's a very rough estimate but I think the max-cap cartirges were exhausted after about 350-400 gallons at which time the second stage gets rapidly depleted. I'm sorry but I can't give you very accurate data. I might try stripping the CO2 using one of the membranes from the link boomer provided but from looking at the site I suspect they are $$$. I am thinking that simpler might be better however and I might just add 3 or 4 more mixed bed cartriges. One other idea: Could I run through 1 filmtec membrane then feed the second membrane with the permeate from the first? Even if this required a second booster pump it might solve my problem right? i.e. drop the TDS to 20 then down to 2 to 4 from the second pass? If I did the above with 3 membranes: i.e. cascading membranes with the effluent side going to a third membrane. This wouldn't waste as much water right? Sorry, I'm grasping at straws since the resin costs and constant hassle are frustrating. Last edited by Herpervet; 10/10/2006 at 11:51 PM.

10/11/2006, 12:03 AM	#13
Thefilterguys RC Sponsor Join Date: Aug 2006 Location: Duluth, Mn Posts: 553	Pete interesting with all the hype the maxcap doesn't seem to live up to the claims. Boomer the stripper is interesting but with no pricing I also suspect big bucks but I'm sure you'll have pricing for us. If the price were right a lot of people with well water would be lining up for this. Pete I took a look at you municipal water report but it is very limited with information. I'm not sure if a second booster pump could perform that task Pete. If CO2 is an issue you could bubble off the CO2 from your RO water and then pass it through your DI but you still have that 20 TDS. Really you should be getting better TDS from your membranes I cant remember if you added the Aquatec auto flush valve? Jim __________________ RO/DI Supplies & parts www.thefilterguys.biz We Custom Build Each System Phone 218 724-8000 Current Tank Info: 40 OCEANIC STRETCH HEX FRESH HEAVY PLANTED, 58 OCEANIC LPS, Monti’s ,Softy’s, 18 Nano Zoo’s , 11 Nano, 70 OCEANIC SPS New 200 Cube on the way

10/11/2006, 04:27 AM	#14
Steven Pro Registered Member Join Date: Nov 2001 Location: Pittsburgh, PA Posts: 9,376	I do use an Aquatechnik Kati-Ani unit (as does Anthony), but I don't think the resins are that much superior to anything one can buy from someone like SpectraPure. The big difference is the Kati-Ani is rechargeable and the recharging chemicals are dirt cheap in comparison to the disposable, mixed resin bed DI cartridges that come with RO/DI units. Looking at your numbers, 400-500 TDS coming into the RO with 20 coming out, that would mean your membranes are rejecting 95-96%, if I did the math right, which seems normal. I would continue to use the RO, but would consider adding a Kati-Ani in place of the disposable, mixed resin cartridges. You would probably start saving money after about a year depending on the cost of the mixed resin cartridges and what size Kati-Ani you get. The big question that you must ask yourself before purchasing is, are you comfortable doing the recharge? I have been using a Kati-Ani for over 8 years and am very comfortable doing the recharge. But, you must answer that question yourself. __________________ Steven Pro, yep that is my real name. Current Tank Info: Twelve 600 gallon tubs located in a greenhouse

10/11/2006, 06:40 AM	#16
Randy Holmes-Farley Reef Chemist Join Date: Apr 2001 Location: Arlington, Massachusetts Posts: 86,233	I agree that recharging is a potential advantage for some folks, but it is not something that I'd choose for myself. FWIW, all issues about the high "purity" of the DI resin are gone once you recharge with ordinary chemicals available to DIY'ers. I also do not consider high purity important for reef aquaria at all. I detail how RO/DI system work here: Reverse Osmosis/Deionization Systems to Purify Tap Water for Reef Aquaria http://reefkeeping.com/issues/2005-05/rhf/index.htm __________________ Randy Holmes-Farley Current Tank Info: 120 mixed reef

10/11/2006, 09:00 AM	#19
Steven Pro Registered Member Join Date: Nov 2001 Location: Pittsburgh, PA Posts: 9,376	I do not run RO, just the DI. Although, I did add a common household water filter before the Kati-Ani and use a 0.5 micron carbon block filter in there. The #2 set I had was approximately 2.5" in diameter and 24" tall. My new #10 set is about 6" in diameter and 36" tall, so these are significantly larger than the standard 10" mixed resin bed cartridges available. I have heard of people getting low yields with DI-only unit's made by Aquarium Pharmaceuticals and Kent, but as I recall, both are rather small. I don't have a TDS meter. Actually, I did just get one, but have yet to open up the box and use it. I just recharge them when about 3/4ths of the color changes. Regenerating is fairly easy. You dilute the chemicals and allow them to drip through each half of the Kati-Ani for about 30 minutes, similar to setting up a kalkwasser drip. Then just flush them out and they are ready to go. __________________ Steven Pro, yep that is my real name. Current Tank Info: Twelve 600 gallon tubs located in a greenhouse

10/11/2006, 11:08 AM	#21
Thefilterguys RC Sponsor Join Date: Aug 2006 Location: Duluth, Mn Posts: 553	OK that clears some things up and your right about small housings, most are using 10" cartridges. The last person I questioned, after flushing was only getting forty gallons of pure water with 10" cartridges per regeneration. One resin would last three times as long as the other. Regeneration is done out side of the housings and cartridge correct? You never did give us you tap water TDS do you know? Jim __________________ RO/DI Supplies & parts www.thefilterguys.biz We Custom Build Each System Phone 218 724-8000 Current Tank Info: 40 OCEANIC STRETCH HEX FRESH HEAVY PLANTED, 58 OCEANIC LPS, Monti’s ,Softy’s, 18 Nano Zoo’s , 11 Nano, 70 OCEANIC SPS New 200 Cube on the way

10/11/2006, 12:44 PM	#23
rick rottet reefkeeper// propagator Join Date: Sep 2003 Location: illinois Posts: 1,440	I also use the Aquatechnics Kati/Ani. (not that I'm a "highly regarded folk") Tap water TDS = 680 - 760 I am using the same series 10 as Steven. I can get less than 300 gallons at -0- TDS when running straight tap water. By 350 gallons, the TDS would read higher the tap water (which I don't understand how that is possible, but thats what the monitors read). The series 10 is advertised to be able to process 9,800 gallons of "very hard" water before needing recharged. After I installed (4) 100 GPD RO membranes before the DI set, the TDS exiting the RO was around 8 and I could run about 6,000 gallons of RO product water throught the DI before the TDS reading would creep up to 2. BUT, there would have been 18,000 to 24,000 gallons of water wasted, plus the iron level in my tap water would plug and clog the membranes in that same two months. I installed an aspirating iron removal system (Marlo, Inc.). Tap water TDS is still around 580 - 620 after the iron removal system, but no more membrane troubles in about a year. I can still get about 6,000 gallons between recharges of the DI, maybe could get more, but I like to recharge when it goes from -0- to 2. I would like to say, I agree with Steven. Recharging the units is fairly simple. Fill a big plastic container with water and the chemical (muriatic acid for the kati, sodium hydroxide for the ani) and let it siphon through the DI units, then rinse them through when the recharge is done. __________________ Beware the hobby that eats- Benjamin Franklin Current Tank Info: 4 x 210 gallon prop system

10/11/2006, 02:45 PM	#24
honeybee Premium Member Join Date: Dec 2001 Location: Charleston, Ill Posts: 186	I too am using the Aquatechnics Kati/Ani units. I use rain water stored in a concrete cistern. The TDS is about 40 but I started with the resin columns because of high nitrates and phosphates. I now run the cistern water through a Pur-FloII with booster pump which reduces the 40TDS to 1TDS I expect the #2 column will last a long time. I will recharge when the Kat column is down 80%. I like the idea of reusing the resin rather than filling the land fill with DI cartiages. Honeybee

10/11/2006, 03:58 PM	#25
Boomer Bomb Technician (EOD) Join Date: Aug 2002 Location: Duluth, Minnesota Posts: 11,842	rick Couple of quick ones ? 1. What is the vol. ratio of water to HCL in the container ? 2. Vol of sodium hydroxide to water ? 3. What do you mean by siphon or do you mean just let the cartridge fill and then let the water run out.? 4. Shouldn't there be a time constraint, as in x min in container ? __________________ If you See Me Running You Better Catch-Up Seawater Chemistry, Geology, ID Marine Life, Collecting Science Books, Explosives Technology, Audiophile An explosion can be defined as a loud noise, accompanied by the sudden going away of things, from a place where they use to be.