UV Sterilizer....good or bad?

[fishman1234]

I was contemplating getting a UV sterilizer for my 4 month old 125 gallon tank, 160 gal with Sump. I was just wondering if its a good thing or bad thing to get......I heard they take out bad micro organisms but they can also take out the good. Does this mean i would need to supplement my tank? Any input helps thanks.:thumbsup:

 

[SkiFletch]

UV sterilizers have their place and function, but they need to be well understood for judicious use of them. I have one that I operate on a periodic basis. I find it's BEST function is to control small green algae that tends to grow on the glass. Every now and again, I have rapid growths of the stuff where I'm scraping the glass daily and barely keeping ahead of the stuff. When that happens I fire up the sterilizer for a few days, kill the populations of it and then turn it righ back off.

I'll also turn it on for a few hours following an aiptasia killing spree with the attempt at killing any released spores. No idea if that helps or not, but I do it.

I used to attempt to use it to combat/prevent ich, but after loosing most of my fish to an ich outbreak many years ago while running UV 24/7 I've concluded it doesn't work well enough for that reason to use it. Still keep it around though cause it's great at controlling those algae outbreaks.

 

[tmz]

Mostly over rated, particularly for disease control in my opinion. I have several on the shelf. They can kill some bacteria and algae spores though that's not necessarily a good thing in every situation.

 

[oldimpala]

Honestly; I ran one for quite a while.

In fact, you asked about the one I had for sale, and used to run months ago...

It's tough to quantify on a tank with so many other variables; overall, I think I need to clean my glass more, but, realistically that could be a skimmer adjustment, RO filter change, or any host of other things.

I continue to run one on my QT/Sick tank, just because I feel it can't *hurt* if a fish is ill. The cost of a pump and light is nominal; and if it saves or helps save, a life great.

Overall; they're alright. There's a particular store in North Tonawanda (Hint: It's not the nice looking one) that sells them as a panacea; they aren't. Only good husbandry is.

Can it be an effective secondary tool in a well executed arsenal? Yeah. Do you need one to have a nice or healthy tank? No.

Can I ask why you're investigating one?

 

[Allmost]

proper UV will kill anything passing by it.

if you dose carbon in system to promote growth of bacteria, UV is not good, it will kill the same ones u are trying to grow.

if you do not dose carbon, there is no down side to UV.

 

[Flanders]

if you do not dose carbon, there is no down side to UV.

Sure there is. Bacteria has a function in reef tanks whether you dose carbon or not. There is a downside to using UV just as there can be a downside to using a skimmer. It all depends on what you want to accomplish.

 

[Allmost]

Sure there is. Bacteria has a function in reef tanks whether you dose carbon or not. There is a downside to using UV just as there can be a downside to using a skimmer. It all depends on what you want to accomplish.

percentage of free floating bacteria to the ones colonizing the sand, rock and ... is nothing.

bacterioplankton systems [dosing carbon] are different story though

 

[Flanders]

percentage of free floating bacteria to the ones colonizing the sand, rock and ... is nothing.

bacterioplankton systems [dosing carbon] are different story though

The bacteria counts in this study I consider to be a lot more than nothing. 150,000 per ml, etc. Just because the numbers go up exponentially when carbon is dosed doesn't mean the bacteria isn't normally there.

http://www.advancedaquarist.com/2011/3/aafeature

 

[Foody]

Every now and again, I have rapid growths of the stuff where I'm scraping the glass daily and barely keeping ahead of the stuff. When that happens I fire up the sterilizer for a few days, kill the populations of it and then turn it righ back off.

What is the difference between cyano growing on the substrate and algae growing on the glass? Is glass algae not a sign of either nitrates or phospates present in the water? I recently posted how Chemi-Pure Elite was finally winning the war of algae growing on my sand bed. It's hard to say for sure but it seems that the algae on my glass is also diminishing. Someone help me understand the similarities and differences.

 

[fishman1234]

Very informative so far....so the answer still stands, they are good and bad. So dosing of iodine and other nutrients would probly be a must then...yes?

 

[SkiFletch]

Well, all are photosynthetic organisms. Therefore the growth of all of them will be affected by levels of P and N in the system. Of course P and N are just blanket categories. Some forms of algae use different molecular compositions of phosphorous and nitrogen better than others. Chemipure would certainly remove those nutrients so you would in theory see a reduction in all algaes.

Cyano does have one nefarious difference to other more complex eukaryotic algaes. Cyanobacteria can fix N2 gas dissolved in water directly to assist in it's growth. Which is part of the reason it's so hard to kill

 

[tmz]

bacterioplankton systems [dosing carbon] are different story though

Huh?
Denitrifying bacteria are primarily benthic not planktonic. There may be some planktonic bacteria in play but I don't think you can characterize an organic carbon dosing system as planktonic. Do you have a source or reason to think so?
Organic carbon dosing ecourages benthic facultative heterotrophs. There are some in the water column as they break away but they colonize surfaces; bet there are some ammonia oxidizers andother bentic bacteria flating about in the water column too. That's one of the problems I have with the cited study in post 8;it ignores benthic bacterial growth.

I do think a properly sized uv will kill bacteria ,since they are very small and don't need much radiation for lethality, algae spores are a little bigger but likely to be killed by uv; protozoans are much larger and need substantial radiation to kill them. Folks use them and they don't seem to do much readily apparent harm.
I used them for years and then I decided I wanted thre benift of phyoplanton and bacteria as tehy metabolize metals and such. Killing bacteria and other smaller organisms disrupting the food chain is not a goal of mine.

A uv can also generate a lot of heat .

Mostlyuvs are good to clears up green water and algae or bacterial blooms .It won't do much for diseases even those with a free swimming(planktonic phase) phase

 

[tmz]

BTW to be fair I went back over the study and found this:

One concerning point in the experiment described in Fig. 7 involves the role that the UV sterilizer might play in influencing bacterial levels; Are we killing significant numbers of bacteria by UV treatment, thus suppressing population growth? The UV sterilizer in use is a 57W flow-through model from Aqua Ultraviolet. In order to probe this question, we re-ran the "week-in-the-life" experiment with the UV sterilizer off, but the skimmer on continuously, Fig. 8. The observed bacteria/mL values over the course of 5 days fluctuated between 60K and 90K (~ 50% change) for this particular time period. Thus, there did not appear to be any significant bacteria population increase in the water column when the UV sterilizer was off, and it is probably safe to conclude that the UV sterilizer does not have a significant effect on the bacteria population levels in the tank's water column.

The finding is interesting but the conclusion that uv has no significant effect on bacteria plankton levels in the tank's water column is perplexing and I think flawed.

It has long been held that when a uv is used on a closed single pass system like an aquarium, bacteria that don't pas through will just grow faster to take up the slack driven by available nutreints. In hatcheries and water treatment facilities single pass systems are used and uv can get 99% killr rates for bacteria. So even though , the survivors eqilibrate back to almost pre uv levels in a tank the uv is killing a lot them continuously and the dead bacteria are ikely releasing stuff as they degrade. Also there isn't any thing to indicate shifts in the types of bacteria pre and post uv,so that may be a concern. Again benthic bacteria will just keep trucking though since they wont pass through the inside of a uv unit.

 

[tmz]

So dosing of iodine and other nutrients would probly be a must then...yes?

Dosing iodine is certainly not necessary . I don't know what you mean by other nutrients.
Uv or no uv would not have anything to do with a need to dose iodoine or trace elements in any case.

 

[tmz]

What is the difference between cyano growing on the substrate and algae growing on the glass? Is glass algae not a sign of either nitrates or phospates present in the water? I recently posted how Chemi-Pure Elite was finally winning the war of algae growing on my sand bed. It's hard to say for sure but it seems that the algae on my glass is also diminishing. Someone help me understand the similarities and differences.

Both the algae on the galss and cyanobacteria are limited by low inorganic phosphate PO4 and to some degree by low fixed nitrogen. Chemi pure elite is a mix of granulated ferric oxide(gfo) and granulated activated carbon(gac) along with some di resin which is useless in salt water. So the gfo which removes inorganic phosphate, silicate and some metals would reduce diatoms, green algae and cyano bacteria. The granualted activated carbon takes up organic materials that hold nitrogen and phosphorus removing them before they degrade to inorganic forms thus helping to reduce inorganic phosphate ammonia, nitrite and nitrate .

 

[Gary Majchrzak]

great thread!

great thread!

reminds me of discussions we used to have years ago around here. Looks like everythings pretty much covered.

I can throw in my two cents: UV can be used as a tool for controlling microalgae growth but it comes at a cost that (personally) I don't wanna pay.
Microalgae growth isn't necessarily a bad thing (in fact, what a great indicator!) and microalgae can be limited by other means.
Bottom line on UV IMO: money spent on filtration for your reef aquarium is better spent elsewhere.

Thank goodness we've moved beyond blaming the lighting!

 

[Flanders]

It has long been held that when a uv is used on a closed single pass system like an aquarium, bacteria that don't pas through will just grow faster to take up the slack driven by available nutreints. In hatcheries and water treatment facilities single pass systems are used and uv can get 99% killr rates for bacteria. So even though , the survivors eqilibrate back to almost pre uv levels in a tank the uv is killing a lot them continuously and the dead bacteria are ikely releasing stuff as they degrade. Also there isn't any thing to indicate shifts in the types of bacteria pre and post uv,so that may be a concern. Again benthic bacteria will just keep trucking though since they wont pass through the inside of a uv unit.

I agree. their conclusion is not exactly flawed because the living bacterial numbers seem just as unaffected whether the UV is killing some off or not. I think you are exactly right as to the reason, but it's just kind of funny that they didn't take the logical step and even take a stab at that themselves.

 

[tmz]

:wavehand:Thank goodness we've moved beyond blaming the lighting!

Funny you should mention it.

I added a 48inch blue light reef brite led across the front top of my 120. The sps on top were shading the front a little too much even with dual 250 halides and vho actinics and I wanted to get a little extra light there.
The light is angled toward the front rock face but some spills pretty directly onto the front glass. The overall effect is very pleasing to my eye and seems to make the corals there happier.
It did increase phytoplankton growth on the front glass and coraline there but not a lot ; just enough that a mid week swipe with a mag float handles it. Before that weekly swipes with occasional coraline spot removal were all that I did.

I'm sure if I upped the ante on PO4 removal and NO3 removal ,I could make the glass stay almost perfectly clean except for some bacteria perhaps. But I don't think eliminating micro flora and fauna entirely is a good thing .Personally, I like having a little phytoplankton and plenty of bacteria in the system . This is the same logic that drives my aversion to sterilization techniques like uv or ozone.
Lighting though it can obviously play a role is the last thing I would blame for over grown glass, the recent observations notwithstanding.

 

[Gary Majchrzak]

I understand what you're saying, Tom

I understand what you're saying, Tom

however.. some folks might find that post confusing.
Usually.. spectrum shift is blamed for an increase in nusiance algae growth.... resulting in recommendatins to change the bulbs if they're old.

In my particular aquarium I encourage micro flora and fauna. Sterility is to be avoided.

 

[tmz]

I agree.
I was making some of the same points you were.

To clarify:

Some phytoplankton and diatoms is good; 0 is bad.

Manipulating lighting will only take you so far and not very far at that and wont permanently end a glass or substrate algae problem.imo though it might reduce it a bit for a while but at a cost to photosynthetic organisms in general.
In my case, it's not a problem; just sharing an observation.

It would have been easy to conclude the new light causes the glass to be "dirtier" and therefore the tank less healthy and extrapolate that to point where reducing light or playing with spectra became the first reach to keep algae at bay but that's not the case imo. Nutrient control is.

Further,controlling nutrients doesn't mean eliminating them or phytoplankton as far as I'm concerned .Zero N and P is not the goal despite the approaches taken in so called Ultra Low Nutrient Systems( a meaningless term).
Getting the right balance between imports( foods etc) and exports, removal media, skimming, mechanical filtration,etc in a specific aquarium is the goal.
Just getting to a point where the aquarium looks good and levels of inorganic N and P don't harm the organisms or cause a lot of unsightly invasive nuisance algae is what I aim for. In my case, it's around .03ppm PO4 and 0.02ppm NO3.

I really don't think reeftank water should be sterilized(uv, ozone, hydrogne peroxide, etc) since many of the effects on the biology of the tank and the organics in it including the availability of organics to bind free toxic metals may have some undesireable long term effects.

Just one other anecdote on uvs.
I did try a large one 39watt on a 29 gallon quarantine tank. Don't care about organics there and figured sterilizing the water ,even in the recirculating system might help with a relatively high radiation rate and pass through rate.
I was surprised by the heat; the temp wouldn't drop below 83 even with no heater or lights , an open top and ambient room temperature of 70.
So simply running a larger uv to kill larger organisms like crytocaryon irritans that pass through it can easily pose temp problems particularly in a sensitive qt situation and temp should be monitored if a large unit relative to tank size is used.
Even if it was large enough to kill the parasites passing through it,it would never touch those on surfaces or in the fish and that bunch would take up the slack, although a temporary density reduction might be helpful .