UV... any down sides???

[TwoTankAmin]

Some cells which are damaged but not killed by UV exposure are able to heal themselves. However, for most things if the UV level and exposure times are proper, it pretty much kills it all. Also, UV research is not limited to its use in water, specifically aquariums. UV is being used in lieu of chlorine/chloramine in some drinking water systems.

UV is used as much for killing pathogens in the air as it is in water, probably moreso. Also, the technology has changed over the years. Research into continuous v.s. pulsed is one example, and then either combining different types of UV or using specific frequency on different microorganisms has also gained in standing for effectiveness.


Wei Luo, Anjun Chen, Min Chen, Wei Dong, Xiaoyan Hou,
Comparison of sterilization efficiency of pulsed and continuous UV light using tunable frequency UV system,
Innovative Food Science & Emerging Technologies,
Volume 26, 2014, Pages 220-225, ISSN 1466-8564,

https://doi.org/10.1016/j.ifset.2014.10.002.

(https://www.sciencedirect.com/science/article/pii/S1466856414001520)

Abstract:

Whether or not pulsed UV light was more bactericidal than continuous UV was still debated. The aim of this work was to compare the disinfection efficiency of continuous and pulsed UV light at different frequencies. A tunable frequency UV system was designed to allow indicator bacteria to be exposed to continuous or pulsed UV light with a same low pressure mercury lamp, which can emit UV light with a wavelength of 253.7nm, and the pulse frequency was adjustable. The germicidal ability against Escherichia coli and Salmonella spp. of pulsed UV light at frequencies 0 (represented continuous irradiation), 2, 4, 6, 8, 10Hz was compared. The results showed that pulse frequency is a factor influencing the ultimate inactivation ability of pulsed UV light and at specific frequencies pulsed UV light was more bactericidal than continuous UV.

Industrial relevance
Pulsed UV light for microbial inactivation has been applied for more than 30years. As a very important factor, pulse frequency has been ignored for a long time. We have demonstrated that at some specific frequencies, pulsed UV light was more bactericidal than continuous UV using low pressure mercury lamp. And if further studies could come to the similar results in inert-gas flash lamps and/or medium-pressure UV lamps and figure out the optimal pulse frequency, it might improve the sterilization efficiency of the existing pulsed UV system.

 

[Oddball59]

Some cells which are damaged but not killed by UV exposure are able to heal themselves. However, for most things if the UV level and exposure times are proper, it pretty much kills it all. Also, UV research is not limited to its use in water, specifically aquariums. UV is being used in lieu of chlorine/chloramine in some drinking water systems.

UV is used as much for killing pathogens in the air as it is in water, probably moreso. Also, the technology has changed over the years. Research into continuous v.s. pulsed is one example, and then either combining different types of UV or using specific frequency on different microorganisms has also gained in standing for effectiveness.


Wei Luo, Anjun Chen, Min Chen, Wei Dong, Xiaoyan Hou,
Comparison of sterilization efficiency of pulsed and continuous UV light using tunable frequency UV system,
Innovative Food Science & Emerging Technologies,
Volume 26, 2014, Pages 220-225, ISSN 1466-8564,

https://doi.org/10.1016/j.ifset.2014.10.002.

(https://www.sciencedirect.com/science/article/pii/S1466856414001520)

Abstract:

Whether or not pulsed UV light was more bactericidal than continuous UV was still debated. The aim of this work was to compare the disinfection efficiency of continuous and pulsed UV light at different frequencies. A tunable frequency UV system was designed to allow indicator bacteria to be exposed to continuous or pulsed UV light with a same low pressure mercury lamp, which can emit UV light with a wavelength of 253.7nm, and the pulse frequency was adjustable. The germicidal ability against Escherichia coli and Salmonella spp. of pulsed UV light at frequencies 0 (represented continuous irradiation), 2, 4, 6, 8, 10Hz was compared. The results showed that pulse frequency is a factor influencing the ultimate inactivation ability of pulsed UV light and at specific frequencies pulsed UV light was more bactericidal than continuous UV.

Industrial relevance
Pulsed UV light for microbial inactivation has been applied for more than 30years. As a very important factor, pulse frequency has been ignored for a long time. We have demonstrated that at some specific frequencies, pulsed UV light was more bactericidal than continuous UV using low pressure mercury lamp. And if further studies could come to the similar results in inert-gas flash lamps and/or medium-pressure UV lamps and figure out the optimal pulse frequency, it might improve the sterilization efficiency of the existing pulsed UV system.

Kia Ora Amin, hope your well. Very interesting extracts. I'm sure the big players must have that on R & D, if they come to the market with something "better" they'll grab that share of the market, it would be the marketing departments dream, but if they all feel what we've got is enough then it won't change, I'd also be interested in costing of different forms of UV as mentioned (tuning in the right frequency) as that would obviously be a big factor.
I test pre production tech for a couple of big Chinese companies and wright reports on usability, ergonomics, reliability etc... and often the cost of quite a small change means they're happy to live with something which isn't a game changer.
There's also the argument "if it isn't broke don't fix it". Which I don't ascribe too, I'd always chase improvement, and probably so would most R & D departments, but the marketing department are the powerful ones who actually govern change by making financial arguments are the ones often holding back improvements and the "if it aint broken....." argument is the one they often throw at you.
One thing I wasn't sure about in the studies you kindly gave is the power output needed and life of equipment, both game changers alongside cost.
But if someone did bring something more effective to the table and it was affordable I'd buy it. The fact that this has been studied for so long and demonstrated more efficient yet not picked up by companies makes me think there is a limiting factor such as above. Maybe electronics are needed to be added etc... which would push up the price a lot, a hard fight and argument to make given the UV tech we have now works fine for the most part. But as usual a great read Amin. Thank you. Kia Kaha. Phil.

 

[OnlyGenusCaps]

can organisms get UV resistant??? in a way that some diseases get resistant to antibiotics, or like get UV "tanned" so they don't burn as easy, like we do to the suns rays???

This is an excellent question!!! I think @Colin_T hit the nail on the head that we probably don't have the research base to say definitively. Certainly, eukaryotic organisms can evolve means to deal with high levels of UV by increasing their cover (e.g. pigment, pubescence, etc.), and I believe there are organisms that have evolved greater capacity for DNA repair to some extent, certainly in the context of other mutagens. But, the way we use UV is to try to cause enough damage to microbes as to shut down cell function. Which is a much higher bar to clear for physiological responses. So if I had to guess, I would say resistance to UV in microbes could evolve - but I don't think it's an easy one for that to happen on, compared with say single chemical antibiotics.

 

[Magnum Man]

That has always been the problem with aquariums, is they are contained systems, so any organism that gets in, either reproduces or dies there... typically they can't go away... if the aquarium was a snapshot of a section of pipe of continually flowing water & we could treat that whole diameter of pipe up stream from our containment section ( like Byron listed his utility water system ), we could kill everything going into the tank... however, I agree, that since we are sending sanitary water into the bigger tank to be blended, & we can't UV treat out captives... in theory, there will always be those organisms that don't get sucked into the UV... increasing the flow rate will reduce numbers, but as long as the exposure time to the UV is long enough to render the organism inert... but this recirculation, & pumping at maximum values is perfect for building resistant strains..

all this sounds pretty dismal towards making totally sanitary conditions... but do we really need sanitary conditions in our tanks... as long as we are reducing to inert, enough of the organisms, that they don't flourish in our tanks, we can maintain conditions... as long as our fish are healthy in the 1st place, & we keep organisms at a level that they do not succumb

the controlling nature of humans, we want everything perfect & sterile... but do we really need that... all said, I've not needed UV... yet... likely a day will come, where I'm going to wish I had it... I assume they are separately powered, & I'm running out of outlets around my tanks... 20 years ago, when I set them up, I thought I had added plenty... they are all full now, with a few powerstrips added where needed

 

[Alice B]

Positive for UV: I had a Regal Tang who got exposed to ich, and when Regal Tangs get ich it comes back and comes back and comes back. Treating anything saltwater is tricky (and because someone has had their fish for months or a year in their tank doesn't mean they are not carrying anything, that's how Dory got ich.) I put her in a 30 long with its own filtration and ran a UV light, external so she wasn't seeing the light, and got her clear consistently after about 6 months. I emptied the 55 of fish and ran live rock and corals only for those months to clear the tank

 

[Oddball59]

This is an excellent question!!! I think @Colin_T hit the nail on the head that we probably don't have the research base to say definitively. Certainly, eukaryotic organisms can evolve means to deal with high levels of UV by increasing their cover (e.g. pigment, pubescence, etc.), and I believe there are organisms that have evolved greater capacity for DNA repair to some extent, certainly in the context of other mutagens. But, the way we use UV is to try to cause enough damage to microbes as to shut down cell function. Which is a much higher bar to clear for physiological responses. So if I had to guess, I would say resistance to UV in microbes could evolve - but I don't think it's an easy one for that to happen on, compared with say single chemical antibiotics.

Kia Ora, a very interesting reply, but would the organism need to survive regular or constant exposure to develop an "immunity"? Maybe in lab conditions an organism could be manipulated to develop a resistance?
As you say there doesn't seem to be enough documented research, but anecdotally UV does have a high efficacy in aquarium settings. I agree about the chemical tolerance, increasing as fish are at the base level a living organism no different to us humans and we know we can develop an immunity through prolonged over exposure. I hate the chemical route anyway as so much appears snake oil, and what does definitely work is incredibly aggressive towards the environment if you are for example zapping black hair algae. I enjoyed reading this.. thank you. Kia Kaha. Phil.

 

[Oddball59]

That has always been the problem with aquariums, is they are contained systems, so any organism that gets in, either reproduces or dies there... typically they can't go away... if the aquarium was a snapshot of a section of pipe of continually flowing water & we could treat that whole diameter of pipe up stream from our containment section ( like Byron listed his utility water system ), we could kill everything going into the tank... however, I agree, that since we are sending sanitary water into the bigger tank to be blended, & we can't UV treat out captives... in theory, there will always be those organisms that don't get sucked into the UV... increasing the flow rate will reduce numbers, but as long as the exposure time to the UV is long enough to render the organism inert... but this recirculation, & pumping at maximum values is perfect for building resistant strains..

all this sounds pretty dismal towards making totally sanitary conditions... but do we really need sanitary conditions in our tanks... as long as we are reducing to inert, enough of the organisms, that they don't flourish in our tanks, we can maintain conditions... as long as our fish are healthy in the 1st place, & we keep organisms at a level that they do not succumb

the controlling nature of humans, we want everything perfect & sterile... but do we really need that... all said, I've not needed UV... yet... likely a day will come, where I'm going to wish I had it... I assume they are separately powered, & I'm running out of outlets around my tanks... 20 years ago, when I set them up, I thought I had added plenty... they are all full now, with a few powerstrips added where needed

Kia Ora, great reply, I'm a dedicated user of UV, 24hrs, even if it's just considered a prophylactic. Except when cycling a new tank when it will kill the bacteria we are trying to foster. I think people are overthinking this far too much. Good tank maintenance, lighting (understanding what lighting encourages algae), and water quality are really all thats needed. I see UV as a belt and braces approach. It will render algae inert, but it will still need filtering out or physically removing if it's established so don't let it get that far although it's inevitable at some stage. I think thats the bottom line.

 

[Oddball59]

Positive for UV: I had a Regal Tang who got exposed to ich, and when Regal Tangs get ich it comes back and comes back and comes back. Treating anything saltwater is tricky (and because someone has had their fish for months or a year in their tank doesn't mean they are not carrying anything, that's how Dory got ich.) I put her in a 30 long with its own filtration and ran a UV light, external so she wasn't seeing the light, and got her clear consistently after about 6 months. I emptied the 55 of fish and ran live rock and corals only for those months to clear the tank

Kia Ora, Hi Alice, Just out of interest how was she exposed to UV surely she wouldn't survive direct contact with UV? Or was the ich treated medically and the water treated with UV to stop reinfection? My own thoughts are to see UV as a prophylactic to be run 24 hrs.

 

[Alice B]

Kia Ora, Hi Alice, Just out of interest how was she exposed to UV surely she wouldn't survive direct contact with UV? Or was the ich treated medically and the water treated with UV to stop reinfection? My own thoughts are to see UV as a prophylactic to be run 24 hrs.

I had an external UV light, water ran thru it, fish did not. It was an 8 watt Pond UV. so the fish didn't see th e light, was not exposed to it. Only the water was treated with UV. 24/7 for several months.,

 

[Endlersendlers]

UV does not and will not kill most of whatever is in the water because all the water cannot pass through it into a second aquarium. My city water is treated with UV, but it is effective because the water leaves the reservoir, passes through the UV, and then disperses through the water mains. It does not go back into the reservoir to be reinfected as it does in an aquarium.

UV will not eliminate all bacteria or algae from your tank water but will decrease the concentration of it. I don’t think this makes it worthless or ineffective, but it can be optimized for a particular system and there is plenty of literature to support it’s role in improving water quality in a recirculating system such as aquariums, and articles supporting this have already been posted by others. It is sterilization that cannot be achieved in these types of systems but that is not the goal here. The goal is a decrease in waterborne pathogens, hopefully before they become well established on surfaces. That is achievable.

 

[OnlyGenusCaps]

would the organism need to survive regular or constant exposure to develop an "immunity"?

Good question! If we are talking about having a population of microorganisms developing resistance to something like UV, all that would need to occur is for a population of the organisms of interest to pass through the UV with some dying and others surviving by variation in their tolerances to the light (not by chance alone). If this happens, the offspring population on the other side of the UV filter would then be better suited to suited to surviving a similar pass in future (assuming this trait can be passed down to them either genetically, or epigenetically). The thing about UV is that it disrupts DNA, and therefore could mutate the resistance genes into being ineffective again. It also tends to have a high efficacy rate, leaving few surviving individuals to reproduce, and those likely by chance. In an aquarium setting, individuals are apt to end up being exposed multiple times, reducing the likelihood or survivorship further. And lastly, even if the survivors made it based on some form of improved tolerance, they would ten be returned to the tank to breed with any individuals which did not pass through the UV selective pressure, further reducing the likelihood of resistance evolving (to be perfectly honest, I'm not sure this last one comes in given that properly sized UV results in tank water passing though completely and often, but theoretically it could be a factor).

 

[Oddball59]

That has always been the problem with aquariums, is they are contained systems, so any organism that gets in, either reproduces or dies there... typically they can't go away... if the aquarium was a snapshot of a section of pipe of continually flowing water & we could treat that whole diameter of pipe up stream from our containment section ( like Byron listed his utility water system ), we could kill everything going into the tank... however, I agree, that since we are sending sanitary water into the bigger tank to be blended, & we can't UV treat out captives... in theory, there will always be those organisms that don't get sucked into the UV... increasing the flow rate will reduce numbers, but as long as the exposure time to the UV is long enough to render the organism inert... but this recirculation, & pumping at maximum values is perfect for building resistant strains..

all this sounds pretty dismal towards making totally sanitary conditions... but do we really need sanitary conditions in our tanks... as long as we are reducing to inert, enough of the organisms, that they don't flourish in our tanks, we can maintain conditions... as long as our fish are healthy in the 1st place, & we keep organisms at a level that they do not succumb

the controlling nature of humans, we want everything perfect & sterile... but do we really need that... all said, I've not needed UV... yet... likely a day will come, where I'm going to wish I had it... I assume they are separately powered, & I'm running out of outlets around my tanks... 20 years ago, when I set them up, I thought I had added plenty... they are all full now, with a few powerstrips added where needed

Kia Ora, another good reply. You're right about our human need for order, but you can never achieve order in an aquarium, something will always happen a dead fish hidden somewhere causing spikes in Ammonia etc... I see the UV as a no brainer, once you've made that initial investment they run on pennies. I'm torn when you used the phrase "system" (Definitely not being critical of you mate) but I prefer to see the tank as a habitat, and a well scaped one as a functioning work of art. I've just invested in a "Meross power strip which connects to all smart phones with six individually controlled sockets. (I use HomeKit). But really my lights Fluval plant 03 switch off on their app, and I'm paranoid about having a timer on my Co2 with the solenoid failing and dumping. But as an electrical engineer I know this shouldn't happen as the default position, ie no power is for the valve to close. I get frustrated by all those cables and pipes, which I try to hide behind plants or a background. Keep well Magnum. Regards, Kia Kaha, Phil.