# How to destroy BGA with external UV lamp



## kekon (Aug 1, 2005)

Being frustrated with eliminating BGA in my tank (which appeared several times throughout the year) i thought of finding different way of killing it. Erythromycin is more and more difficult to get as it is being withdrawn from pharmacies. So, i bought a new 11 watt UV lamp normally suitable for 10000 liters ponds. Two day before water change i sucked out all the BGA which i could find in the tank with a hose. Then i switched the UV lamp on. I thought that if BGA can grow in every place in the tank so its spores must exist in the water column so it could be destroyed by UV radiation. On water-change day, i uprooted some plants which were slightly covered with tiny amounts of BGA and washed them under the tap thoroughly. The UV was still working during WC. I also stirred up the substrate in order to release BGA spores out of it into the water column. After WC, UV was working for one extra day. Fe deficiency appeared shortly after the treatment but i dosed 0,5 ppm Fe and 0,3 ppm Mn and deficiency disappeared quickly. A month has passed since i did all that stuff but BGA hasn't returned !


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## DonaldmBoyer (Aug 18, 2005)

Well, BGA is actually a bacteria, and does not reproduce by spores (sorry to get all nerdy on you). But your UV treatment would kill the bacteria as well! I have found and heard that H2O2 (hydrogen peroxide) is very effective at killing BGA, clado, and other types of algae too, as long as it is used in small amounts over a few days. But, it seems like your UV sterlizer is the ulimate way to proceed! Good job!


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## kekon (Aug 1, 2005)

Thanks 
I also heard about H2O2 used as "algae control agent" but nobody was able to say, what amounts can be added into the tank without harming plants. I wonder if it also destroys micro nutrients. Before i switched the UV on, there was 0.5 ppm Fe. The very next day in the morning it was 0 ppm.


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## DonaldmBoyer (Aug 18, 2005)

Regarding peroxide treatments, it really has to do with the tank's volume. 

I use a large eyedropper to apply peroxide if I need to, and have treated both my 40 gallon cube and 100 gallon. I get it "full," which is 5 mL, and I squirt about an inch away from the infected areas. H2O2 is heavier than water until it reacts, so it "falls" on top of the area, reacts to form water and oxygen (once it starts bubbling). I have used up to 20mL in my 40 gallon at a time, and the only ill effects that I have experienced was the loss of a few snails that were unfortunately near the area where the peroxide was applied. I haven't lost any fish, and plants, or any shrimp ever. 

It is wiser to treat a larger tank over the course of a few days, treating one area at a time. Because you are also killing bacteria and microscopic creatures when you apply the H2O2, I would recommend at least a 10% water change between treatments to prevent toxicity due to the decay of these bateria and microfauna.

Just speaking from my own experience, the wise use of peroxide is probably the cheapest and best treatment to use against problematic algae that I have used, and I will never use anything other than peroxide again.


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## freydo (Jan 7, 2006)

you can also use EM tablets that you can get at your LFS, but i would use this as a last resort if your UV doesn't work. the EM tablets work, but the resulting environment may not be good for invertebrates, as i found out. but this is what happened to my setup where all my amano shrimp got cooked shortly after i finished the treatments.


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## Bert H (Mar 2, 2004)

Are your nitrate levels ok? I ask because low nitrates are a typical cause for bga.


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## kekon (Aug 1, 2005)

NO3 is low (below 5 ppm) because any attempt to raise it above 5 ppm results in stunting in many plants. I had BGA also when NO3 was at least 10 ppm.


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## Kelley (Aug 27, 2006)

This is an external UV lamp, not an in-line UV sterilizer, right? 

Do you worry about mutagenizing the inhabitants of your tank? UV is powerful stuff. The beauty of an in-line sterilizer is that it is contained. 

Please, you be careful too! Wear eye protection and limit exposure to your skin.


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## ruki (Jul 4, 2006)

*Re: H2O2*



DonaldmBoyer said:


> Just speaking from my own experience, the wise use of peroxide is probably the cheapest and best treatment to use against problematic algae that I have used, and I will never use anything other than peroxide again.


This is very interesting. I will have to try it.

What concentration do you use and where do you get it?

It's pretty cool stuff. It decomposes into water and oxygen gas (2 H2O2 → 2 H2O + O2) But it's pretty reactive, so that must be what takes on algae so well.


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## Kelley (Aug 27, 2006)

2% H2O2 is what is commonly sold in drugstores. It is the stuff that is used as a disinfectant for cuts. I have safely used a concentration of about 1ml/gal, though I noticed that my apple snails did not like it at all and closed up for an hour following treatment. I would be hesitant to exceed this dose in my tank. Still, it is effective at killing algae. 

Another reason that I would not just dump it in your tank is that while it decomposes into o2 and H2O, it also creates reactive oxygen species (free radicals) that are toxic to all life at a high enough dose.


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## kekon (Aug 1, 2005)

I've never used H2O2 however i'll try it if it's necessary. I have 30% H2O2 at home 
I know it's very effective when removing algae from plants before putting them into the tank but it can easily destroy them.


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## JJJohnson (Mar 29, 2007)

I would love to hear more about the UV lamp and how you're applying it. (I had a BGA infection that went on for years, and I thought I had tried everything, but this is a new one for me.)

Is the lamp at the surface? If so, how do you control *your* exposure to it?


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## kekon (Aug 1, 2005)

The UV lamp i use is an external one (linear). It is connected to the canister filter output so purified water flows from the filter through the lamp into the tank. The lamp kills bacteria and other parasites that exist in the water column but doesn't have any effect on aquatic life in the substrate, filter and plants. It is extremely effective when eliminating so called "green water" or killing protozoa which makes water turn cloudy (the problem can be eliminated within 2..3 days with a help of UV lamp). UV lamp should be used only when it is really neccessary (in cases i've written about above). The biggest disadvantage of it is that UV radiation destroys micronutients chelators. This especially concerns iron chelator which breaks down into iron sulphate (FeSO4) which is very unstable in the water (it is stable however in strongly acidic one). In turn, FeSO4 quickly converts to Fe(OH)3 (rust) which settles down on the bottom of the tank and becomes unavailable to plants (it is insoluble). So, after UV treatment one should quickly add high micro fert dose to restore all the micronutrients.
Using flourescent UV-bulb placed in the cover in the tank would be very unwise thing. It could kill your plants and fish because they would be directly exposed to UV radiation.


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## ruki (Jul 4, 2006)

I'll echo the previous comments.

The UV lamp does really well at cleaning up green water. I have a unit attached to the output of my canister filter. (Actually the unit is strapped on to a converted Magnum 350 hang-on-tank. Pretty comical looking, but effective.)

I don't know if it will help against BGA. If the BGA is stuck to the surface of a plant, it can't get dragged into the UV unit to get killed.

A good caution on micro destruction too from the previous poster. I've had the UV unit on for a couple of weeks to get rid of a persistent greenwater problem, but now the plants aren't looking so good... Time to turn it off until the next greenwater outbreak.


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## houseofcards (Feb 16, 2005)

ruki said:


> I'll echo the previous comments.
> 
> The UV lamp does really well at cleaning up green water. I have a unit attached to the output of my canister filter. (Actually the unit is strapped on to a converted Magnum 350 hang-on-tank. Pretty comical looking, but effective.)
> 
> ...


I've run a UV 24/7 on my 72G tank for almost two years and I've never had a deficieny associated with it. IMO it's a win, win for fish and the overall ease of maintenance. If you have low organic waste in your tank and a larger biofilter (plants and filter) you will probably never have BGA in your tank.


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## defdac (May 10, 2004)

> I've run a UV 24/7 on my 72G tank for almost two years


How often do you change the bulb? The usable life span of a T5 UV-bulb is for example 9000 hours, a little more than a year...

I've read about as many people having trouble with micro deficiencys as those that have not running an UV-filter. I have managed to induce it myself with an UV-filter and seen a couple of friends induce it when they have fought off green water letting the filter run 24/7 for several days/weeks...


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## ruki (Jul 4, 2006)

You don't need to run it constantly. :lol:

After I turned it off, the green water didn't return. I know it will sometime later, but why burn the electricity or use up the bulb when I don't have to? I'm guessing I'll have it on for about one week out of 10.


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