UV sterilisers?

GlenD

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26 Jun 2019
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I've always used a 25w UV with a flow rate of around 550LPH and have never had fish disease or algae issues. But Ive not used one on a planed tank yet.

I normally have my UV on when lights are off/overnight. The house is colder and with no lights on, it keeps tank temp more stable.
 

Zeus.

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If I remember correct Green Aqua have them on all their tanks and @Filip Krupa has them on his 2000l beast.
I dont have them on my 500L and from what I read they make little to no difference hence the reason I dont have one fitted
 

Filip Krupa

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Can they really help control Algae? Anyone have any success with them.
A proper UV steriliser should help with green water, but wont make a difference on other "attached" forms of algea.

IME, UV is one of those things that are great in theory, but hard to "see" the benefit of. Just too many variables and confirmation bias looms large.

Hope this helps.
Fil
 

GlenD

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I'm not 100% but in my view most algae and bacteria have spores. Any spores taken into a 25w+ UV and a flow rate of under 600L will neutralise them. Thus helping prevent their buildup?
 

Filip Krupa

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Any spores taken into a 25w+ UV and a flow rate of under 600L will neutralise them. Thus helping prevent their buildup?
presuming you have a proper STERILISER, not just a clarifier. The difference is important, and not helped by most clarifiers being marketed as sterilisers.

IMO if youre doing something to inadvertantly encourage e.g. BBA with too strong lights, poor flow and Co2, a steriliser will not stop BBA from spreading.

Even with a 100% spore kill rate inside the UV. Its not possible to kill every last spore in the column, and the ones left will attach and thrive in the right conditions.

But Ive not used one on a planed tank yet.
Very different ball game.

Fil
 

zozo

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I'm not 100% but in my view most algae and bacteria have spores. Any spores taken into a 25w+ UV and a flow rate of under 600L will neutralise them. Thus helping prevent their buildup?
I'm not sure if most do, the complete algae universe likely is yet not mapped. I guess the most algae pestering us also reproduce asexualy via cell devision and or fragmentation.

https://www.britannica.com/science/algae/Reproduction-and-life-histories

And do not underestimate the algae toughness, i see a swimming pool in a friends garden each year again. Loaded with Chlorine and it still has a bacterial biofilm with green algae buildup if not mechanicaly cleaned regularly.

If you look up tests done with UV light on tanks infested with free floating green algae than it takes the UV almost a week to eradicate this, meaning it's not an instant kill. Depending on the pumps turnover you can calculate approximately that is needs to pass the UV quite often to be effective if it takes 5 to 10 days to clear a 200 litre tank with a turn over between 5 to 10 times per hour. Than spores from larger algae spp. need a culture medium to grow, in our case thats the biofilm it attaches to, on the plants, hardscape or glas. This slimy and sticky biofilm is everywhere in your tank. collecting spores and fragments floating around, likely also before it ever passes the filter.

Than weekly water changes are about exualy and likely more effective by means of removing whats in the water column in stead of sterilizing. :) If doing both is beter?.. A lot of professionals recomend this.. But over the decades keeping fish and plants in aquariums and such i never used UV light and yet never suffered green water issues and never had a fish i obtained in healthy condition getting sick in one of my containers. This experience kinda tells me, if you ever need an UV light there is something else seriuosly wrong. Than UV is not the solution but just an expensive sterilizing band aid on a insufficiently washed smothering wound that is about to get seriously infected the moment the band aid is taken away.

An UV light also doesn't heal fish already infected.
 
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