# UV or a better filter?



## winsonli (Feb 18, 2007)

I have a 25 gallons tank which I decided to rescape. My old setup had weak lights and an internal filter. CO2 was DIY. Substrate was aquasoil amazonia. There was slight algae appearance, but acceptable. A month ago I removed all the plants and left it unplanted as I am too busy (public exams) to design a new scape. I also installed a stronger light (54W of fluorescent in total).

After a month of plantless and strong lighting conditions, there is now major algae issues and green water. I added a lot of riccia, hoping it would compete for nutrients with algae. It did help at first, but then after I scraped off the algae on the glass surface one day, the algae problem started to lose control.

Now I'm thinking of investing in a canister filter or an UV sterilizer. I would prefer the UV sterilizer. The question is how effective would an UV sterilizer be at solving algae problems, not only GW, but all kinds of algae? What wattage of UV do I need?

Also, would the existing Fluval 2 plus internal filter be powerful enough to drive the water into the UV sterilizer, or do I need a powerhead?

Actually I don't quite understand the function of a filter. I always thought that algae problem is due to excess in nutrients, NPK in particular. That means if there are enough plants to take up most of the nutrients, there would be no algae. If that's the case, then what is the purpose of a filter? I'm quite confused as I've heard that excess nitrates is a cause of algae, so why would we want biological filtration which converts ammonia to nitrates? What is the role of a filter in algae control?


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## goalcreas (Nov 20, 2006)

You could get one of these HANG ON TANK CANISTER FILTERS and use it in combo with Diatom powder. You can use it on any tank you want for how ever long you need it and then put it away until the time comes that you have to use it again. You don't have to add any powerheads, any other filters, or plumb anyting at all. It is quick, simple and easy.
I know people who have cleared up green water and other algae blooms with it and I have borrowed one, used it for a few hours and green water was gone.

http://www.drsfostersmith.com/Product/Prod_Display.cfm?pcatid=3597&N=2004+22777

Here is the powder in small packages, but you can get it at a Pool store in larger packaging for really cheap, but it might be too much, like 25 or 50 lbs.

http://www.drsfostersmith.com/produ...&Ntx=mode+matchallpartial&Np=1&pc=1&N=0&Nty=1


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## winsonli (Feb 18, 2007)

Thanks for your reply. 

What does the diatom powder do to remove the algae? Any adverse effect on fish?

Could I simply put the diatom powder into the internal filter or a hang on filter which I have laying around?


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## goalcreas (Nov 20, 2006)

Can't say that I can put into words why or how it works, hopefully somebody else who knows the specifics will post.
I do know that that filter uses a micron filter and with the powder, it gets clogged and exhausted, so if you tank is really bad, sometimes you run it for a few hours to a day and then take out the micron filter and clean it and add more powder. This is not something that you would run all the time, but most people I know don't run their UV lamps all the time either, they would plumb them in a bypass and run it when needed.

This filter, being a mobile hang on canister is really handy when you have multiple tanks also.


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## furballi (Feb 2, 2007)

Short term: Change 80% of the water and don't use the light for 3 days.

Long term: Reduce lighting to 3 or 4 hours...less if you don't have plants.


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## jeff63851 (Feb 23, 2005)

Hey winsonli,

Welcome to APC. First of all there are many types of filter. The filter that you currently have, a Fluval 2 plus is exactly the same filter that I use on my turtle tank. If you didn’t add anything extra to it, you probably only have foam in it. The main function of a filter is to remove excess nutrients and solid waste products through pumping water into filter media, which houses bacteria that takes in these nutrients. This is the reason you use tank water to wash these filter media. Without these bacteria, a filter would be useless. However, carbon can also be added to the filter to take out these excess nutrients. However, many of us on APC don’t use this since we need these nutrients for the plants.

Getting another canister filter wouldn’t help much, it would take along time before you start seeing effects. Diatom power is just a really fine type of sand (i think, correct me if I’m wrong) that filters out small microscopic particles from the water, which is why it is extremely effective in eradicating Green water. I don’t think that a diatom filter would harm your fish, but I’m not sure because I never used one. A UV would also work since it uses ultraviolet light to kill of the Green water. It would work, but is extremely costly. I doubt that the Fluval 2 plus would be powerful enough to pump water into the UV sterilizer.

Adding some more fast growing plants such as stem plants could help reduce the algae and GW. When I had Green water, I never used a UV sterilizer or extra filters. What I did, as suggested by furballi, was a huge water change and a 3 day blackout. When doing a blackout, make sure the tank don’t get any sunlight. This can be done thorough taping black trash bags around the tank. In addition, I also added more plants. In the end, the GW was gone, and so were some of my plants.

Sorry for the long post, good luck dealing with your algae problem!


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## winsonli (Feb 18, 2007)

Thanks for the replies.

So I guess I'll just have to "reset" the tank to the algae-less condition by a 80% WC and blackout, introduce a lot of plants and it should be fine, right? I want to make sure that my equipment (especially the Fluval 2 plus) didn't cause the GW as the new plants would be wasted if they're covered by algae again.


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## furballi (Feb 2, 2007)

winsonli said:


> Thanks for the replies.
> 
> So I guess I'll just have to "reset" the tank to the algae-less condition by a 80% WC and blackout, introduce a lot of plants and it should be fine, right? I want to make sure that my equipment (especially the Fluval 2 plus) didn't cause the GW as the new plants would be wasted if they're covered by algae again.


Also clean the filter.


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## jeff63851 (Feb 23, 2005)

winsonli said:


> Thanks for the replies.
> 
> So I guess I'll just have to "reset" the tank to the algae-less condition by a 80% WC and blackout, introduce a lot of plants and it should be fine, right? I want to make sure that my equipment (especially the Fluval 2 plus) didn't cause the GW as the new plants would be wasted if they're covered by algae again.


yep, if you do all that, the green water should be gone within two weeks or so.


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