Again, we are in agreement. What I meant to say, and my understanding from a conversation with a UV engineer, is that UV can kill ich parasite at a very high dose when the parasite passes through. The dose required for marine ich is much higher than fresh water ich and requires very large UV that is not a hobby grade. In our tank, of course, it is not possible to have all parasites to pass through the UV, for all reasons you mentioned.
UV Sterilizer
- Thread starter KevinsHVAC
- Start date
Again, we are in agreement. What I meant to say, and my understanding from a conversation with a UV engineer, is that UV can kill ich parasite at a very high dose when the parasite passes through. The dose required for marine ich is much higher than fresh water ich and requires very large UV that is not a hobby grade. In our tank, of course, it is not possible to have all parasites to pass through the UV, for all reasons you mentioned.
slief
RC Sponsor
Yep. We are clearly on the same page then! :beer:
HippieSmell
Occupy Reef Central
If we can't eliminate ich using UV, why are we worried about eliminating plankton?
slief
RC Sponsor
The UV can reduce populations of smaller pods. It's also an oxidizer so having the flow rates too low will impact other things in the water that corals feed on. The slower the flow rate, the greater the impact. It's kind of a debatable subject as to how great the impact but there are recommended flow rates for marine aquariums and I stick to those flow rates. Why reduce the tanks foods sources if you don't need to yet can still reap the benefits of the UV sterilizer?
HippieSmell
Occupy Reef Central
Does it reduce pods? Apparently, it doesn't even reduce bacterial populations according to an Advanced Aquarist article.
Growth rate of a population is impacted the most (by far) by the age of reproduction, not by the number of offspring. So, an organism that reproduces at an early age, such as bacteria, has a rate of reproduction that apparently outpaces the sterilizer's ability to impact the total population number. The fact that the bacteria eventually become sterilized has no appreciable impact on total population. Whether or not this holds true for pods is unknown to me, but the fact that pods aren't always in the water column leads me to believe they'll be OK.
You say the lower the flow rate, the more oxidation there will be. I don't see how this is true. Assuming there is a limit to how much any given volume of water can be oxidized, there must be a limit where dwell time no longer has an impact. Therefore, any increase in flow rate will actually oxidize a higher percentage of system water, up to a point where the bulb wattage becomes the limiting factor.
slief
RC Sponsor
I think you misunderstood the article. A UV will not impact denitrifying bacteria or good bacteria because that bacteria resides primarily within the substatre. It absolutely does impact waterborne bacteria.
Contact time has a direct impact on oxidation and sterilization rates. The lower the flow, the greater the contact time. It's not rocket science. I would suggest you do some reading on how UV's work and their uses in water filtration including but not limited to water purification, pond applications etc. While water purification UV's use more powerful and or different wavelength bulbs, there is much to be learned from that becaue the principles are the same.
Regarding pods and other life passing through the filter, since you don't believe me, I would suggest calling AquaUV. They are experts who have done their case studies and research. They are one of the most weill respected UV sterilzer manufacturers in the industry and will be happy to spend time on the phone explaining it to you and will most certainly confirm what I've stated above. I've spent enough time on the phone with them myself and have been using UV Sterilzers for over 20 years. There is a reason why companies such as AquaUV don't recommend running too low of a flow rate in our applications. I'd suggest asking EA as well but since Pentaire took over, there doesn't seem to be anybody there who knows anything about marine and reef aquariums anymore.
HippieSmell
Occupy Reef Central
No, the Advanced Aquarist article was measuring bacteria in the water column. See for yourself: http://www.advancedaquarist.com/2011/3/aafeature
Oxidation is not a matter of simply slowing down flow rates and getting "more" oxidation. Any molecule has a chance to be oxidized governed by probability. The rate of oxidation is dictated by the bulb wattage, not flow rates. More wattage increases the probability of oxidation as the water flows through the UV. Decreasing flow rates will increase the probability of that water getting oxidized, but the TOTAL amount of oxidation remains the same. In fact, if you slow the flow rate enough, total oxidation will decrease, because there's a higher percentage already oxidized in the chamber and can't be oxidized further.
Sterilization is the same thing. There's a CHANCE that an organism will become sterilized as it passes through the UV. Slowing the flow rate increases that chance. But, slower rates can't keep up with the explosive growth rates of bacteria. I'm not sure what the growth rates of pods are, but I don't see too many going over the overflow.
I would like to point out that I'm concerned with closed, circulating systems. Sterilizers used to treat water flowing from an external source to a closed system are different, and flow rates are more important.
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slief
RC Sponsor
Interesting article. I had not read that one up until now. I know (informally) some of the authors and will reach out to them as it raised some questions in my mind pertaining to their results and bacteria targets. It's long been proven for example that UV sterilizers are very effective in eliminating and preventing bacterial blooms as an example which leaves plenty of reason for questions. They mentioned a 57 watt AquaUV but they don't mention flow (unless I missed it) and it appears they tested on a 175 gallon system which is well within the range for that sterilizer. Anyhow, it certainly was an interesting read but I have to question some aspects or at least would like to have a better understanding of their flow and testing targets beyond just the size of the bacteria.
"Oxidation is not a matter of simply slowing down flow rates and getting "more" oxidation. Any molecule has a chance to be oxidized governed by probability. "
Logic would stand to reason that slowing the flow rate down increases the chance or probability of oxidation. While it may be true that some bacteria reproduce fast or faster than the sterilzer can oxidize or kill them, that is certainly not the case for all bacteria. I have seen immediate impacts on Cyano bacteria for example or they typical bacterial blooms what ever type of bacteria those may be. I am not an expert or even close to it when it comes to bacteria but I do have a lot of experience with UV sterilizers and have seen evidence of their effectiveness with my own eyes on different bacteria forms as mentioned above. That said, bacteria isn't really the prime reason for using a UV. It is one reason but oxidizing organic compounds for water clarity is a key one. It's impact on algae forms in the water column falls into that equation also. I won't touch on parasites as that is not something I really use them for. That said, I'd love to get an expert from AquaUV to chime in here regarding bacteria and other life forms because I do believe that flow rates have a direct correlation to their effectiveness when it comes to smaller forms of life whether it's water born bacteria, pods or even some planktonic forms of life.
You mention pods going over the overflow. The best location for a UV on an aquarium is on a closed loop and not on the return side or cicultaing in or out of the sump. While they are similar, closed loop is generally more effective. Especially where high flow return pumps are concerned. Also the location of the closed loop intake is relevant when it comes to pods since they are generally placed closer to the bottom of the tank where pods tend to congregate compared to the overflow which is located near the waters surface and not a preferred location of pods.
Anyhow, you do raise some interesting points. While your points and the article raise questions in my mind, the discussion is interesting none the less.
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DamonG
New member
Ok, this discussion made me go clean up my AquaUV 57 watt unit.. So slief(here I go again asking, but on a student topic), help me out with this one please..The question that I never fully understood with their units, and it made more sense to me from reading this thread, is the flow.. So my system is approximately 240 gallons.. With that unit, for clarity, correct me if I'm wrong, but I'd want to be pumping at least 4 times that 240? Which rounding, is about 1000 gph? Is that correct?
The EA unit I had was easy, but I never really, fully understood the ratings in the aqua uv instructions. So when I moved,I just never reconnected it.. However, my water is fairly clear, but if I can get it even clearer, that would be awesome!
From note 5.. rip note 7
The EA unit I had was easy, but I never really, fully understood the ratings in the aqua uv instructions. So when I moved,I just never reconnected it.. However, my water is fairly clear, but if I can get it even clearer, that would be awesome!
From note 5.. rip note 7
slief
RC Sponsor
My best advice if you want to question things would be to talk to a manufacturer of UV sterilzers. I'd start with AquaUV since they also manufacture their own bulbs and have invested heavily in case studies, testing etc. You can easily reach somebody there who knows about marine tanks and will spend all the time you want on the phone explaining things much better than I can. I'd think they know what they are talking about regardless of Advanced Aquarists test on bacteria populations.
Hmmm.. Seems your most recent reply is now gone?? Weird..
HippieSmell
Occupy Reef Central
My recent post is still there for me. It would be interesting for an Aqua UV rep or expert to make an appearance on the forum. Pull some strings!
slief
RC Sponsor
Weird. I don't see it anymore. Funny you mention the AquaUV rep chiming in. I was thinking the same thing and was considering reaching out to them for that very thing. Obviously I am a big proponent of UV and AquaUV for that matter. My comments are based largely on my experiences as well as my research and conversations with their reps. I am not immune to being wrong and as I said, you raise some interesting questions. It would certainly be great for them to chime in and I will see what I can do. It's a real shame they aren't a sponsor here. They would be a great asset to the community. They really do do their research and we could all learn from them. If I have time tomorrow, I will reach out to them and see if I can convince them to chime in.
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