I recently purchased a canister filter with a built-in UV light. I had been under the impression the UV was active against algae only. I am now reading it is equally effective on bacteria, sparing the nitrifying bacteria. Does anyone know what is going on with these lights? I am keeping it on for now, but I’ve read the replacements are pricey and they burn out quickly. I do not have an algae problem in this particular tank and may not replace it if that is all it is really good for.
UV light built into filter
- Thread starter Jacky12
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I have a 9w UV but its stand alone, not integral to the filter.
UV will kill algae spores floating around in the water as it passes over the UV. It will control green water as that is present in the water. It won't do anything for algae that is growing on surfaces in your aquarium.
UV is good for killing off bacterial blooms. That what I use mine for. Gives me great water clarity in an aquarium that is prone to bacterial blooms. I just run it on a timer for 6 hours overnight every night.
UV can kill parasites etc if the light is powerful enough and more importantly the water has enough contact time with the UV. The integral lights in filters tend to be quite small, and with the high flow rate through the filter don't provide enough contact time to kill parasites. Fish stores often use UV in their sump filtration systems to prevent infections spreading from one aquarium to another when they are running multiple aquariums off one sump filtration system.
My small UV has been going for 6 hours a day for 3 or 4 years without needing the lamp changing and the lamp is about £20 to replace. I'm seeing replacement sunsun 5w, 9w and 11w lamps all for about £10.
UV will kill algae spores floating around in the water as it passes over the UV. It will control green water as that is present in the water. It won't do anything for algae that is growing on surfaces in your aquarium.
UV is good for killing off bacterial blooms. That what I use mine for. Gives me great water clarity in an aquarium that is prone to bacterial blooms. I just run it on a timer for 6 hours overnight every night.
UV can kill parasites etc if the light is powerful enough and more importantly the water has enough contact time with the UV. The integral lights in filters tend to be quite small, and with the high flow rate through the filter don't provide enough contact time to kill parasites. Fish stores often use UV in their sump filtration systems to prevent infections spreading from one aquarium to another when they are running multiple aquariums off one sump filtration system.
My small UV has been going for 6 hours a day for 3 or 4 years without needing the lamp changing and the lamp is about £20 to replace. I'm seeing replacement sunsun 5w, 9w and 11w lamps all for about £10.
Thank you, Aiken, that’s great news. I will keep it running. I just checked for replacement bulbs at Amazon and they were only two for $14. Reasonable enough. I have never used UV in the past. But the new filter line all comes with them built-in. I did go with the Polar Aurora, their largest model. It was not solely the price that drove me away from Fluval. I have many FX4s & FX6s and a smaller canister they manufacture. The replacement parts are high & the customer service is not good. They allow me one question every 24 to 48 hours. They make great effort to drive me away in the form of demanding numerous videos that I don’t see are related to the issue. It worked. I gave up on them and sought resolution elsewhere.
The only thing to be aware of is that UV is indiscriminate in what microbes it kills. If you are trying to cycle a tank, UV will kill any of those microbes you need that are floating about in the water and prevent them establishing on your filter media, substrate etc. Once they are established, at least to some degree, it should be OK to turn on the UV as you arent then relying on microbes in the water column finding their way to where they need to be.
Shame about Fluvals customer service. I've only contacted them once with a query about spare part compatibility between their old 06 range and the new 07 range.
Shame about Fluvals customer service. I've only contacted them once with a query about spare part compatibility between their old 06 range and the new 07 range.
Andy Sager
Aquarium Advice Addict
As Aiken said, kill rates are all based on the length of time the water is under the UV light. The all in one filter/UV setups are new to me but based on what I know with the old style, flow rates were posted in the manufacturer's catalog. In some of the wholesalers I worked in, we had bulbs as long as 8' with 5 bulbs per unit or if the bulbs were shorter, there were 8 bulbs in succession all based on the flow rates of our pumps.
Here's a site that can help you figure out what size you need or if you are really getting anything beneficial with your flow rate: Choosing the Right Size UV Sterilizer: What Do I Need for My Aquarium?.
As for how long the bulbs last, unless bulb technology has advanced tremendously, the bulbs lasted mainly 1 year.
Here's a site that can help you figure out what size you need or if you are really getting anything beneficial with your flow rate: Choosing the Right Size UV Sterilizer: What Do I Need for My Aquarium?.
As for how long the bulbs last, unless bulb technology has advanced tremendously, the bulbs lasted mainly 1 year.
Fluvals UV is 30000 hours, so 3 or 4 years running 24/7.
I think my UV is 25000 hours.
I fully cycled the new filter by stealing bits & pieces of media from my larger established filters. I did squeeze some cycled sponges into the tank to help along the two new sponge filters in there. I sure hope they got to the BB before the UV did. I have never had a bacterial bloom in a tank and an algae problem only once because the tank sat on a ledge with a window behind that was not adequately blocked off. Too bad it killed off many beautiful plants & came on so suddenly.
Thanks, Andy!
I've never really figured out why that tank is prone to bacterial blooms, but it is overstocked so theres that. My panda corys breed and I struggle to rehome them quicker than i get new ones appearing. It's the main tank in the living room and I like it busy though.
Frequent water changes help not 100% solve it. It's significantly overfiltered and again that helps but didn't solve it. Tried water clarifiers. In the end got a small in-tank UV, 24 hours later water is totally cleared. I removed it after a few months, and the water stayed clear for 3 or 4 weeks, then the cloudiness returned. So I put the UV back and have just kept it there and never tried removing it again. Doesn't do any harm.
Frequent water changes help not 100% solve it. It's significantly overfiltered and again that helps but didn't solve it. Tried water clarifiers. In the end got a small in-tank UV, 24 hours later water is totally cleared. I removed it after a few months, and the water stayed clear for 3 or 4 weeks, then the cloudiness returned. So I put the UV back and have just kept it there and never tried removing it again. Doesn't do any harm.
I'm not really sure. If there are microbes present in the sponges, then they should just multiply without needing to go waterborne and risk being killed off by the UV.
But, if you can turn off the UV until cycled it would seem a reasonable precaution.
But, if you can turn off the UV until cycled it would seem a reasonable precaution.
Andy Sager
Aquarium Advice Addict
If the flow is slow enough and the microbes are in the wandering stage in the water column, then Yes, they are getting whacked.
If the tank is empty or just have well established fish in it, there's no real harm in keeping the UV off until the tank cycles. If you want to be more proactive, do one sponge in the bucket with the bb water from an established sponge filter, add some ammonia and test that bucket water every couple of days to see the ammonia converted to nitrite or to nitrate. ( If it's converted to nitrate, you have both nitrifying microbes present so you can put the sponge into the tank then. )
. Thanks.
Andy Sager
Aquarium Advice Addict
