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UV sterilizer and algae
- Thread starter idris
- Start date
It's a legit way for your LFS to increase their sales and profits for sure! 😉 Not a great deal of use beyond that on a planted tank.
I tried it once, not helpful at all for algae. may help with fish health if you get a sufficiently powerful unit that can kill pathogens - eg: in an outbreak in a community tank, quarantine the sick fish, whip out the UV (high power/low flow rate is key) for the main tank to prevent spread of disease to healthy fish.
That's what I thought. I guessed it could slow the spread of algae between plants, but I wasn't convinced it would do much else.
Wash your mouth out! 😀😀😀
There is a lot of snake oil in aquaristics. But UV filters are not in that group. UV filters are useful to remove pathogens from the water, and they do help with bacterial blooms, and with the removal of algae spores and other organisms that are suspended in the water column. They will not work if they are incorrectly set up, which is most often the case.
The water must be exposed to strong UV radiation for a certain amount of time for the organisms to be damaged or destroyed. Otherwise nothing happens. This means that the water must flow through the filter quite slowly. If you use a unit with UV light of ~10W or less (which you will find in the majority of entry level models), the water flow should not exceed say ~100 l/h. If you get a unit with a UV light of 20-30W maybe you can raise the flow to 300-400 l/. However, UV filters are often connected directly to the output of canister filters sometimes generating a flow of +1000 l/h. A UV filter must be connected to a low-flow water circuit (either by building a canister filter bypass, or using a separate circuit with a low-flow pump). Otherwise the filter will not work due to incorrect installation.
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Hi @idris
It can certainly kill off algae spores and Cyanobacteria when suspended in the water column. As water passes through the UV-C sterilizer carrying spores and filaments, the high energy UV-C damages the DNA of living matter that passes through it. That's all there is to it. In order for this to be effective, dwell time is all-important. As the name suggests, 'dwell time' is the time that the bacteria and/or algae are exposed to the UV-C light. And this is determined by the physical dimensions of the sterilizer itself and the flow rate. The presence of particulate and dissolved organic matter (POM/DOM) in the water column absorbs UV-C (at 254nm) and can then reduce the effectiveness of UV-C sterilizers.
I have used a UV-C sterilizer to good effect in combatting Cyanobacteria.
JPC
One that seems to be widely available and stresses the low flow rate is the 'Green Killing Machine', available with either a 9w or 24w UV tube. Anyone have experience of these?
MichaelJ
Member
Hi @hwscot yes, I use the Green Killing Machine 9 W UV filter in both my tanks - I have it set on a timer to run for 4 hours a day in the evening. It kills algae spores and pathogens (below a certain size) that floats around in the water column. Beware that the UV light may interact with Iron chelates (essentially breaking down chelating agents) and render Iron less available to the plants, so try and dose micros outside the timeframe where the UV light is running. Yes, it zaps beneficial bacteria that lives in the water column as well, but the bacteria we rely on are mostly in the substrate and filter... Otherwise, I cant think of any downside to running a UV filter (if you can easily hide it somewhere).
Cheers,
Michael
Cheers,
Michael
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Hi @hwscot
I use the Mini Green Killing Machine. I can provide more information tomorrow if you wish but, now, I must take a break.
JPC
Thanks, guys,
To come clean .. I just bought one. As it happens, I set it up just yesterday. The 9w. It's a tank that's only been running a few weeks and doesn't have a serious problem with algae, having passed quickly through a diatom stage, and the tank layout lets me hide it quite easily. I panicked a bit when I saw the thread and the degree of scepticism. It's reassuring to have some positives, and interesting to get the experience on running times.
To come clean .. I just bought one. As it happens, I set it up just yesterday. The 9w. It's a tank that's only been running a few weeks and doesn't have a serious problem with algae, having passed quickly through a diatom stage, and the tank layout lets me hide it quite easily. I panicked a bit when I saw the thread and the degree of scepticism. It's reassuring to have some positives, and interesting to get the experience on running times.
That was my purpose, yes. Though it can't harm to be inhibiting algae in the water column.
I'm going to have to post a shot of the tank. I know i am. It's possibly the most anally-retentive design, if that's the word, that UKAPS has ever seen. Very rectilinear. But the UV steriliser is certainly well hidden.
This is a very good question.
A suitable* UV unit will damage or destroy a variety of organisms suspended in the water column, including infusoria up to a given size, pathogens, as well as algae spores, including cyanobacteria as @jaypeecee mentioned above in this thread. An UV unit has no impact (at least no direct impact) on the organisms on the surfaces of the aquarium.
* a UV filter that generates sufficient UV radiation exposure given the input water flow, and has sufficient turnover rate given the total water volume.
But there are <studies> <investigating> the effect of UV radiation on some algae sp. using not only UV-C but also the higher wavelength <UV-A and and UV-B>. Studies routinely look at <the impact of UV on cyanobacteria sp.> since bacterial blooms are suspended in water.
I believe there is no evidence demonstrating that UV will not reduce the load of some of the several thousands of algae sp.. Given existing research and how UV is actually used in practice (e.g. in water treatment plants), it is most likely that UV will also reduce some algae sp. in a planted aquarium, but this needs to be demonstrated.
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Hi Everyone,
One of the good things about a UV-C sterilizer is that it can be switched ON or OFF, as required. And this applies whether it is stand-alone or inline. In the case of the latter, it is important to choose a unit that doesn't significantly reduce water flow rate. If using tank medications, manufacturers may advise switching a UV-C sterilizer OFF.
JPC
One of the good things about a UV-C sterilizer is that it can be switched ON or OFF, as required. And this applies whether it is stand-alone or inline. In the case of the latter, it is important to choose a unit that doesn't significantly reduce water flow rate. If using tank medications, manufacturers may advise switching a UV-C sterilizer OFF.
JPC
UVC Sterilization | How Aquarium & Pond UV Sterilizers Work
Information how a TRUE Aquarium, Pond UV Sterilizer/clarifier work. Category A, B, & C Sterilizers. Affect on green water, disease prevention, & Redox
www.americanaquariumproducts.com
The website sells UV products, so obviously they are touting the benefits but when it comes to algae, this is what they have to say:
Mature (stable) aquarium = best solution for algae problems? 😎 (but ok, they want to sell you some magic water to help your tank mature faster...)
Oldguy
Member
I use a 30 Watt unit on a time switch. Dwell time and turn over are critical to its effectiveness.
UVC Sterilization | How Aquarium & Pond UV Sterilizers Work
Information how a TRUE Aquarium, Pond UV Sterilizer/clarifier work. Category A, B, & C Sterilizers. Affect on green water, disease prevention, & Redoxwww.americanaquariumproducts.com
The website sells UV products, so obviously they are touting the benefits but when it comes to algae, this is what they have to say:
Mature (stable) aquarium = best solution for algae problems? 😎 (but ok, they want to sell you some magic water to help your tank mature faster...)
In my comments above I am not defending the usage of UV products as some sort of magic solution to stabilize a tank or to remove algae. But UV products are often discredited as producing absolutely no effects, which is incorrect. UV products do have impact on algae and bacteria suspended in the water, and play a role in situations that require specific water treatments.
So let's not conflate the discussion about "do UV products have any impact on algae and bacteria" with the discussion about "should we use UV products in a planted tank as a primary means to stabilize it and control algae". These are two separate discussions.
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