# Any truth to UV sterilizers?



## Guest (Apr 14, 2008)

Is there any truth to UV sterilizers keeping algae out of aquariums? I've been having a terrible 4 months dealing with massive green hair and brown algae blooms in my 265g. Will a UV sterilizer keep it out of my sight?

I've also heard that they can make the water appear crystal clear. How do they manage to do that?

Besides the obvious pro that UV bulbs help prevent fish illnesses, what are other Pros and Cons of getting one?

Thanks in advance,
~Ed


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## fishyfishyfishy (Dec 24, 2005)

They make your water clearer by killing free floating algae that passes through it. It won't help with the algae growing on your decor. Flowrates needed to just kill the algae can be pretty high making selecting a UV easy and pretty forgiving. But, to kill off bacteria/protozoa etc. the flowrates need to be much slower and larger UVs are needed for it to be effective. The only con I can think of is the addition of a little bit of heat to the water, maybe a degree or two at the most, but that's about it.

Necessary, no, but I a great thing to have on your tank.

Some good info here:

http://www.drsfostersmith.com/product/p ... =3578+4393


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## trigger (Sep 6, 2002)

A uv steriliser does not take anything out of the water, it just kills what comes through it (if it can be killed bu uv that is) The dead stuff that comes out of it, has to be picked up by a mechanical filter.


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## lotsofish (Feb 28, 2008)

If you are going to go to the trouble of adding a UV, you may as well get one that will kill parasites and bacteria too. Most UVs don't come with a pump so they have to be plumbed to your canister or provided a pump. Compare flow rate of pump to UV and pick one that will kill everything.


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## Toby_H (Apr 15, 2005)

The short answer to your questionâ€¦ yes UV lights work very wellâ€¦

I run mine at:
1 W per 10 gal of tank volumeâ€¦
10 gph per 1 W of UV lightâ€¦

This is to fight against parasites as well as green water or free floating algaeâ€¦

UV lights will kill almost everything that passes through the UVâ€¦ obviously this does not include the algae that is thriving on the surfaces in the tankâ€¦ I cannot tell you the science behind this part but I can share this as fact after using several sizes of several brand UV lights on several tanks in several situations over the last 5 yearsâ€¦ Adding a UV light to a tank overridden with algae will reduce the amount of algae that can/will thrive in your tankâ€¦

I suspect that the UV light damages/kills something in the water that the algae use to thriveâ€¦ therefore the surface algae suffers and dwindlesâ€¦ but I have doubts of my own theory as my simple plants have not suffered after adding a UV lightâ€¦

Iâ€™m no scientist and do not pretend to be oneâ€¦ Iâ€™m just some dude that tried UV lights years ago and put them to the test in many situations and have been impressed by them every step of the wayâ€¦


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## Windowlicka (Feb 6, 2008)

In my experience, Absolutely!

I was having a tough time with blooms in my 90g, then my 65g... I added a Coralife 9x to my 90, and within 24 hours the water was (for the first time) crystal clear.

I was so impressed, I put a Coralife 6x on both my 65 and even on my 20g long... No more unwanted algae in the water column (though it remains on the rocks, which is perfect!)

Good luck!


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## Guest (Apr 15, 2008)

If I scrape the algae off the glass, will a UV sterilizer prevent it from reappearing on the glass? Sometimes I get massive blooms overnight so bad with hair and brown algae I can't even see the fish in my tank...


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## jayiw (Jan 16, 2008)

Marduk said:


> If I scrape the algae off the glass, will a UV sterilizer prevent it from reappearing on the glass? Sometimes I get massive blooms overnight so bad with hair and brown algae I can't even see the fish in my tank...


You'll still have algae growth because the algae that floats from your current algae will land on things such as glass, ornaments, etc. but since a lot of it will be sucked through the sterilizer so the growth should not be as much and will be slower to spread. The sterilizer will only kill what goes through it and anything that does not go through it will continue to spread and reproduce. The main thing the UVS does is (like others have been saying) is kill free floating algae and parasites.

Jay


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## Guest (Apr 17, 2008)

So I understand correctly, you're all saying that it won't completely get rid of algae but should significantly reduce it?

And what wattage should I look at getting?

~Ed


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## Windowlicka (Feb 6, 2008)

Marduk said:


> So I understand correctly, you're all saying that it won't completely get rid of algae but should significantly reduce it?


IME, a UV Steriliser will eradicate all algae currently suspended in the water, but will not kill off existing algal blooms that are already "in residence" on your glass/rockwork/decorations (since these existing blooms are obviously not able to pass through the steriliser).

For me this is fine - my fish like to graze on the rock-based algae, but now that algae is growing in a much more 'controlled' manner, and my water is crystal clear. I certainly no longer have problems with white/greenwater, that I did (and that were driving me insane) before adding these gadgets...

Best of luck.


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## Guest (Apr 19, 2008)

So it'd probably be worth it I guess to get one.

What wattage should I look at and what are some good brands to look at?

~Ed


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## boostspike (Apr 3, 2007)

Turbo Twist is a good brand.. 18W rated up to 250g i think.. If need they also make a larger one 36W. best of luck.


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## fishyfishyfishy (Dec 24, 2005)

You really need to look at specs of each unit to determine what size u need. How u plumb it/flowrate along with what you want to kill will all determine what size u need. You also want to turn over the tank volume a bare minimum of twice per hour to be effective as well.


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## Guest (May 8, 2008)

I got a Aqua Ultraviolet 25watt unit up and running now in my sump now with a mag 700gph pump.

Surprisingly though, the past week since I bought the unit and before hooking it up I've been getting green water...my first encounter with it ever... Hopefully thanks to the UV it will clear up a lot overnight.

Anyway I'll let you guys now over the next few days how things go with it.

~Ed


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## gymdog (May 24, 2007)

Ok on the uv sterilizer. will the sterilizer kill good bacteria along with bad bacteria,parasites,and free floating algae. i am one to add "cycle" to my tank.


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## fishyfishyfishy (Dec 24, 2005)

It does not discriminate.

As far as your cycle additive, how destructive the UV will be all depends on the wattage of the UV and the flowrate through it.


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## jayiw (Jan 16, 2008)

gymdog said:


> Ok on the uv sterilizer. will the sterilizer kill good bacteria along with bad bacteria,parasites,and free floating algae. i am one to add "cycle" to my tank.


It will not kill anything that does not go through it. Since your good bacteria in on your filter media and inside your filter it will be fine. If you add any culture and the culture goes through the UVS it's going to be killed. You should never have to add cycle or any culture to an established tank though. The only real problem I would foresee is if you put a UVS in before a tank was cycled and established.

Jay


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## Toby_H (Apr 15, 2005)

nc_nutcase said:


> 1 W per 10 gal of tank volumeâ€¦
> 10 gph per 1 W of UV lightâ€¦


Increasing the flow rate decreases the effeciency... this is why you still see green water...

Just like the algae on the rocks... the "good bacteria" lives on surfaces...

So yes, any "good bacteria" that moves through the UV light will be killed, but the stuff is everywhere and multiplies very quickly once established. In 5+ years of using UV lights I've never had a problem with keeping a tank cycled.

PS (added) - Very good point about the "good bacteria" additives, and I agree completely...


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