Built in UV lamps

[french47]

G'Day,
I have noticed that quite a few external filters are being sold with built in UV lamp, Is this a good idea or just a gimmick? In fact is a UV lamp needed or useful in a planted tank?
Cheers

 

[Nathaniel Whiteside]

Apparently, completely useless. Because the filter flow you require to be fast, and the UV requires a slow flow rate to be of any use.

If you do want a UV, which you shouldn't, then run it on a separate run with a pump.

Better spending your money on a filter with a higher flow rate and some decent plants

 

[ian_m]

From what I have read, yes, UV can have benifit in a planted tank as the UV will kill pathogens and algea spores. A lot of shops with planted tanks, in my experience, have UV units in their filter loop.

However it is most likely the "dwell" time of UV units in filters, the time the water is in contact with the UV is far too short UV thus rendering UV in effective.

Good article on UV in tanks here.
http://www.americanaquariumproducts.com ... ation.html

 

[foxfish]

As far as I understand UV light has no effect on most algaes just the free floating type that gives the appearance of green water.
UV is however used on commercial systems because UV is capable of killing microorganisms such as certain bacteria, viruses, molds & single celled algae.
How much use that is in a planted tank I cant say but they are certainly not necessary.

 

[dw1305]

Hi all,
They aren't totally useless but they are still just more "snake oil" or "magic bullets" really. They sell because the advertisers put together a series of truths and half truths -

"drinking water can be sterilized with UV"......"UV exposure kills bacteria/algae/ciliates" ........ "bacteria, algae, Ichthyophthirius multifiliis are bad"

and then rely on the purchaser to join the dots.

Really powerful (and dangerous) UV units may have a place in commercial set-ups which are aiming to run almost aseptically, but if you aren't they become irrelevant. They grew popular with Koi keepers because of their ability to kill unicellular "green water" algae, but the underlying cause of that algal bloom hasn't gone, those nutrients are still there and other photosynthetic organisms will make use of them if the "green water" algae doesn't.

Edit: I should have said that the article "Ian_m" linked is a good read, and covers the facts, even if you don't agree with the authors conclusion.

cheers Darrel