RO/DI versus Kold Ster-il Filter System.

[KingNeptunesBou]

I was curious if anyone could tell me the difference between an Reverse Osmosis Filtration Unit and a Kold Ster-il Filtration System. What are the benfits of each unit and drawbacks of each unit? I am also interested in seeing aquarium photographs of anyone currently using the Cold Ster-il Filtration as their primary source of filtering their tap water. Thank you for the assistance.

 

[PurdueWaterGuy]

RO/DI removes darn near everything from the water. What levels of impurities that are left are insignificant for reefing purposes. Typical home RO's are only about 25% efficient (some high-end unit apprach 50%) so be prepared to put 1 to 3 gallons of water down the drain (or on the garden, etc) for each gallon of RO/DI water you produce.

It's been a while since I looked at the Kold Ster-il information, but if I remember correctly they use some exotic filtration techniques to remove just the offending materials from the water stream (like chlorine and phosphates) and leave things that are beneficial like calcium and alkalinity. They warn on their web site that you should first send them water for analysis to make sure that your source water is compatible with their system. Their filter media isn't cheap, but if your source water is compatible with the system, and the water is also hard, (and consistant over time) it could be a better value over time.

As they say "you milage may vary" - it really depends on what's coming out of your tap.

Hope that makes sense.

Tim

 

[raynist]

On another note, I am using a Kati ani unit to filter my water, that could be another option.

 

[PurdueWaterGuy]

Is there anyone out there using a Kati-Ani after an RO, instead of the DI resin cartridge?

Just curious, it should work......

Tim

 

[raynist]

Is there anyone out there using a Kati-Ani after an RO, instead of the DI resin cartridge?

Just curious, it should work......

Tim

that would probably work really well, should last for a long time between recharges but you would still have lots of waste water.

I have a Kati ani #2 and I get around 300-400 gallons out if it before it needs a recharge.

 

[KingNeptunesBou]

RO/DI removes darn near everything from the water. What levels of impurities that are left are insignificant for reefing purposes. Typical home RO's are only about 25% efficient (some high-end unit apprach 50%) so be prepared to put 1 to 3 gallons of water down the drain (or on the garden, etc) for each gallon of RO/DI water you produce.

It's been a while since I looked at the Kold Ster-il information, but if I remember correctly they use some exotic filtration techniques to remove just the offending materials from the water stream (like chlorine and phosphates) and leave things that are beneficial like calcium and alkalinity. They warn on their web site that you should first send them water for analysis to make sure that your source water is compatible with their system. Their filter media isn't cheap, but if your source water is compatible with the system, and the water is also hard, (and consistant over time) it could be a better value over time.

As they say "you milage may vary" - it really depends on what's coming out of your tap.

Hope that makes sense.

Tim

Thank you for the information. I don't currently live in a house and I'm most likely going to purchase a home in the next 2 years so I think the RO/DI unit would be my best bet. Is their something I can add after the filtration process in order to add some of the beneficial properties back to the water before adding salt mix?

 

[PurdueWaterGuy]

that would probably work really well, should last for a long time between recharges but you would still have lots of waste water.

I have a Kati ani #2 and I get around 300-400 gallons out if it before it needs a recharge.

Yes, but the "waste" water can go back thru the hydrologic cycle. The DI resin is plastic, made from petroleum pumped from the ground, and eventually buried in a landfill. It might seem counter-intuitive, but the RO/Kata-Ani might be more environmentally friendly in the long run....


TIm

 

[spleen93]

A Kati-Ani system IS a DI system. It's a separate cation / anion deionizing resin system as opposed to a mixed-bed deionizing resin system like what most RO/DI systems use. As such, it'll work exactly the same as a standard DI if both are placed after a RO system. As mentioned, the advantage of them it being a separate cation/anion system is that each resin can be recharged as opposed to a mixed resin which can't be. Unfortunately, the chemicals used for recharging can be quite caustic and it's probably debatable how environmentally friendly the recharging process is.

 

[hottuna]

Don't remember reading anywhere on poly bio marine's website that you should send them a water sample first..
The kold steril is a good unit...I have used it and a r/o Di ...each has it's own merit...depends on your source water.

 

[KingNeptunesBou]

Thank you for the information. My hold up on purchasing any unit is that I am going to be purchasing a home in the next 2 to 3 years and have to purchase another unit if my water quality doesn't fit the bill. Does the Kold Steril unit need a booster pump?

 

[PurdueWaterGuy]

A Kati-Ani system IS a DI system. It's a separate cation / anion deionizing resin system as opposed to a mixed-bed deionizing resin system like what most RO/DI systems use. As such, it'll work exactly the same as a standard DI if both are placed after a RO system. As mentioned, the advantage of them it being a separate cation/anion system is that each resin can be recharged as opposed to a mixed resin which can't be. Unfortunately, the chemicals used for recharging can be quite caustic and it's probably debatable how environmentally friendly the recharging process is.

Yup, the Kati-Ani has the two "flavors" of resin in separate cannisters so they can be regenerated without the messy separation step. An yes, it does take concentrated acid and caustic to regenerate, but if you do it right they cancel each other out and all that goes down the drain is a (somewhat warm!) salt mixture.

If one were gentle in the regeneration process, you could get hundreds of regenerations out of one set of resin. (Osmotic shock tends to break the resin beads, golly knows I've fried my share of resin)

So I maintain my position: it might be more environmentally friendly to use an RO/Kati-Ani combo, sending the waste water back thru the hydrologic cycle (or the garden/koi pond, etc) and maximizing the life of the IX resin.

Tim

 

[KingNeptunesBou]

Thank you guys for all the information. What is involved in the process of regeneration? Do you think this is more cost effective over the long haul or could I screw something up in the regeneration process and have to spend more money on resin then replacing standard filters in an ro/di unit?

 

[hottuna]

I just noticed you are in the bronx...NY Water is perfect for a kold steril ...I would try that....IMO...

 

[PurdueWaterGuy]

Thank you guys for all the information. What is involved in the process of regeneration? Do you think this is more cost effective over the long haul or could I screw something up in the regeneration process and have to spend more money on resin then replacing standard filters in an ro/di unit?

My experience with regenerating IX resin is at the tens or hundreds of cubic feet of resin per batch - a little bit bigger than a Kati-Ani

The concept is the same: the resin is backwashed or otherwise "fluffed up", then exposed to the regenerant, typically hydrocloric acid or sodium hydroxide. The pH of the regenerant is somewhat critical, as is the exposure time and flow rate. Too high a concentration of regenerant will cause osmotic shock, breaking the resin beads. After the appropriate exposure time, rinse thoroughly and it's ready to use. And if you regen Cation resin in one container and Anion resin in a second, and mix the effluent, the resulting pH will be close to neutral and safe to run down the drain.

Being a bit of a safety freak, I would advise that you don't venture too far outside your range of experience or "comfort zone". If you don't have any chem lab experience and don't feel comfortable using concentrated chemicals, don't do it.

The impression from the Kold-Steril web site is that they will be quite happy to tell you if their system is a good fit for your source water.

Keep us posted on your progress!

Tim

 

[hottuna]

A friend of mine lived in staten island and used a kold steril exclusively...he had a great reef tank and his alkalinity was allways good...

 

[yardboy]

After reading this link which was somewhat more forthcoming than most Kold-Steril websites, it is a good drinking water filter, but if, like most users of municipal water, phosphate is present in any appreciable amount, it will not remove it. Same with nitrates which are often present in drinking water, so I'll continue to use my regenerated resin RO/DI system!
As for Tim's well-warranted caveat that you should be very cautious in using strong acids and bases, I really need to take a picture of the stack of gallon containers of muriatic acid at the local HD. The bottom ones got wet and the whole stack is sagging to one side. A remarkably cavalier attitude toward an admittedly dangerous chemical.
Oh, and don't even go to YouTube to see what kind of crazy reactions people are performing in 2 liter coke bottles just to see stuff explode. I'm afraid they just aren't listening Tim! :hmm3:

 

[KingNeptunesBou]

I'm thinking I might just stick with RO/DI.