Should Use UV With RO/DI Water ?

[427HISS]

I bought a 5 stage BRS RO/DI system, a lot easier than buying 40 gallons water from our "Supper Saver"grocery store. Theirs is a nice with I think is a 5 or 6 filter system and it's inspected by the city every month. One step is to run the water through a UV sterilizer filter.

So, do you use a UV, should we ?

 

[ccombs]

I bought a 5 stage BRS RO/DI system, a lot easier than buying 40 gallons water from our "Supper Saver"grocery store. Theirs is a nice with I think is a 5 or 6 filter system and it's inspected by the city every month. One step is to run the water through a UV sterilizer filter.

So, do you use a UV, should we ?

Ok, I am no expert, but here is my anecdotal experience.

Most people on the forum do not seem to use a UV on their RODI. Most look at the city water report and choose enough stages of filters that they feel comfortable with to do the job. For me, in Nashville, I did not see anything alarming on the water report and the water out of my faucet is only 160 TDS which is pretty low for city water, so I went 4 stage.

That being said, my neighbor who just moved is a reefer. He chose to put a UV on his RODI water instead of on his tank because he did not want to kill good bacteria in his aquarium. This is where we disagreed. My research and reading suggests that most good bacteria live on the rocks and other surfaces, and won't end up going though the UV at a rate that would wipe their population. I have personally seen a UV in my tank keep disease at bay long enough to keep inhabitants alive long term when they should have died quickly.

Most city water plants use UV before the water gets to you. Obviously there is a long way between them and you, but you get the idea.

In my very very humble and novice opinion, I do not believe you need a UV on your RODI before you mix. If you really want one, get an appropriate sized one for the tank and send an appropriate amount of flow through it with the actual aquarium salt water in use. UV only seems to be successful when it has good contact time with the water and does not move too fast.

 

[Mastiffsrule]

Ok, I am no expert, but here is my anecdotal experience.

Most people on the forum do not seem to use a UV on their RODI. Most look at the city water report and choose enough stages of filters that they feel comfortable with to do the job. For me, in Nashville, I did not see anything alarming on the water report and the water out of my faucet is only 160 TDS which is pretty low for city water, so I went 4 stage.

That being said, my neighbor who just moved is a reefer. He chose to put a UV on his RODI water instead of on his tank because he did not want to kill good bacteria in his aquarium. This is where we disagreed. My research and reading suggests that most good bacteria live on the rocks and other surfaces, and won't end up going though the UV at a rate that would wipe their population. I have personally seen a UV in my tank keep disease at bay long enough to keep inhabitants alive long term when they should have died quickly.

Most city water plants use UV before the water gets to you. Obviously there is a long way between them and you, but you get the idea.

In my very very humble and novice opinion, I do not believe you need a UV on your RODI before you mix. If you really want one, get an appropriate sized one for the tank and send an appropriate amount of flow through it with the actual aquarium salt water in use. UV only seems to be successful when it has good contact time with the water and does not move too fast.

Agreed as ccombs said, but im no expert either. I would assume if anything does get thru th ro/di process it may not survive e the salt environment. But that is based on general thought and not science.

 

[Sleepydoc]

The first question I have is “what are you hoping to accomplish?”

A UV filter on your tank will only kill organisms that pass through it. As such it is limited to what’s in the water column and can only serve to reduce the load, not eliminate it.

The city water is sanitized. Not necessarily sterile but certainly clean. To my knowledge, there are no pathogens to your tank that will survive in DI water. Beyond that where are you putting the UV unit? Between your RO membrane and the DI resin? Between the DI resin and the storage reservoir? Your storage reservoir is far from sterile, so even if you sterilize the water coming into it, it will not remain so.

Putting a UV filter after your RO/DI unit won’t hurt anything but won’t accomplish much either, beyond wasting money.

 

[427HISS]

Why would a system like our grocery store has, that the city controls the filtering which includes UV sterilization, should it be good on our tanks ?

It helps remove Viruses, Bacteria, Algae, Fungi, Protozoa, etc.

Our town has it's own well, not some city slicker large city's system, lol,...so we may not have as a complete filtration as them.

I thought if it would help, hooking it up after the RO/DI, that goes into my water collecting container. There must be a reason that if the city/state has it on these drinking water systems for the public, that we should. We wouldn't need a large one if we are only wanting to make, say 50 gallons for a water change.

 

[Sleepydoc]

Why would a system like our grocery store has, that the city controls the filtering which includes UV sterilization, should it be good on our tanks ?

It helps remove Viruses, Bacteria, Algae, Fungi, Protozoa, etc.

Our town has it's own well, not some city slicker large city's system, lol,...so we may not have as a complete filtration as them.

I thought if it would help, hooking it up after the RO/DI, that goes into my water collecting container. There must be a reason that if the city/state has it on these drinking water systems for the public, that we should. We wouldn't need a large one if we are only wanting to make, say 50 gallons for a water change.

I live in a suburb and it has it's own well too - I'd be willing to bet that the standards are similar across the board for municipal water supplies.

The grocery store is essentially functioning as a restaurant or public water source and as such may have to follow state guidelines/regulation for sanitation. (Of course the other possibility is that it's completely unnecessary, they just put it on so they can say "UV sterilized" an haven't changed the bulb in 3 years so it's completely ineffective anyway.)

Like I said, it won't hurt, I can't see it helping, either.

 

[427HISS]

I don't want to spend time and money (like I have on so many 'products in the hobby) that fail to work, so I'll trust people like you that know much more than I do.
Thanks sleepydoc

 

[High ICP]

Why?

UV kills organisms

There are none of those in RODI

 

[427HISS]

How does RO/DI accomplish that ?

 

[High ICP]

Too big

 

[427HISS]

I've never seen that. Thank you !

 

[Randy Holmes-Farley Verified Community Expert]

There can be bacteria growing on the downstream side of an RO membrane,. Those may periodically be released into the RO/DI, and that's one reason that drinking water systems will use UV.

However, if you do not intend to drink it, there's no reason to be concerned with a small amount of bacteria getting into your tank that is laden with multitudes of bacteria, and gets more from the air, foods, etc. every day.

Thus, while there is no downside to using a UV except cost, I think the upside is too small to make it worth doing for a reef tank.

 

[High ICP]

Randy,

I store my RODI water in a 60G Norwesco food grade tank.

And a biofilm develops on the sides if I don't dry it out.

What are the bacteria eating? Maybe dust (human skin cells)?

Or they eating something from the plastic (like bio pellets)?

 

[Randy Holmes-Farley Verified Community Expert]

Randy,

I store my RODI water in a 60G Norwesco food grade tank.

And a biofilm develops on the sides if I don't dry it out.

What are the bacteria eating? Maybe dust (human skin cells)?

Or they eating something from the plastic (like bio pellets)?

I'm not sure. If its not dark inside, might be a type of cyano.

 

[Dkeller_nc]

One of the most common types of bacterial contaminants in purified water containers and plumbing is pseudomonas species (pseudomonas diminuta is particularly troublesome). Pseudomonads tend to form biofilms, which results in a slimy feel to the inside surface of the container. They also have extremely simplistic and minimal metabolic needs - just the carbon and nitrogen that arrives on dust particles is enough. This genus is the primary reason for UV irradiation at 254nm of purified water systems for food and medical manufacturing. Even that isn't enough, as biofilms will build up on the interior plumbing to the extent that the whole system must be periodically sterilized (typically with a peroxide mixture).

The good news is that pseudomonas is ubiquitous and won't cause issues for a reef tank. While it would be unwise to drink from a system that wasn't maintained and therefore had a large amount of bacteria being shed from the biofilms in the unit, the most common species won't survive in seawater.

 

[427HISS]

Randy & Dkeller,..man, thanks for making what you've described as understandable for non-scientific mind, as with me, with a fourth grade education. lol...