UV light

[Shalmaneser]

I'm looking for a submersible UV light for killing algae. Amazon/ebay is full of junk or stupidly expensive inline stuff. (and even then their failure rate is high). It's just a submersible light and a transformer. Is it too much to ask for something with a low failure rate for a reasonable price?

 

[Lisak1]

Welcome to the GPF! I don't use a UV in my pond - never really needed one for one, and secondly I'm a big believer in addressing the cause rather than the symptom. Algae has a source - address it and you'll eliminate the need for a UV, cheap, expensive or otherwise!

Tell us more about your pond - how old, how many gallons, what kind and how many fish, plants, what kind of filtration, etc. We love pictures!

 

[addy1]

Welcome to our forum!
I have never used a UV light, don't have green water either. Just lots of plants they keep it clean

 

[j.w]

@Shalmaneser Not a uv user.

 

[Shalmaneser]

pond is 2 ft h x 3 ft w x 14 ft l
Bought the property last fall. 5 Koi with a relic of a SunSun canister filter - the label is dust in the wind. I've been tweaking the canister to get full flow AND not drive me crazy with noise. I took the UV apart, dead bulb with water in the chamber. With summer came the algae. It's a full sun exposure. I've got a .2 gal/sec well water trickle going with 5 stones on a ALITA INDUSTRIES Air Pump 6 LPM pump (arrived this week). There's a couple of water lillies, they flowered nicely a week ago. Inoculating 2x (so far) with pondworx bacteria. Ammonia is zero, nitrites are .25 ppm, nitrates are 0. I suppose the free floating green algae are going to stop growing soon.

 

[brc]

Beware that UVC radiation kills everything it touches (not just algae), and could give you cancer. A submersible one that just sits in the pond would kill your fish, plants, skin, eyes, etc. These things need to be installed in a closed chamber where the light can't get out.

You can get just the bulb and ballast for fairly cheap - maybe you could repair the one in the filter you have? There are also inline ones you can buy for well under $100.

The important thing with either type is that water stays out of the electronics, and that they don't run dry. "The bulb is dead and its tube is full of water" is a really common complaint with these. Putting the filter at a higher level than the water (instead of trying to hide it in the ground) and keeping rain off it will help a lot. I'm using a cheap $125-ish canister filter with UV from Amazon, and it's had zero problems so far.

 

[Stephen Noble]

I'm looking for a submersible UV light for killing algae. Amazon/ebay is full of junk or stupidly expensive inline stuff. (and even then their failure rate is high). It's just a submersible light and a transformer. Is it too much to ask for something with a low failure rate for a reasonable price?

I too use natural control and avoid UV sterilizers/clarifiers. But, if you are going to use UV consider this: UV needs lots of 'contact time' in a confined space to be effective. Meaning, the slower the water flows past the UV chamber the more effective it will be. That is why they place the UV bulb in-line in an encapsulated, clear chamber. In my opinion, using a scatter approach by lowering a UV bulb in the pond will be less effective. Besides, your pond most likely gets more UV from the sun in its location than any bulb shining underwater could provide.

 

[Lisak1]

Besides, your pond most likely gets more UV from the sun in its location than any bulb shining underwater could provide.

Good point! I've never actually thought about this... if UV kills algae, and the sun emits UV rays, why are we always blaming "too much sun" for the overgrowth of algae? Does the water filter UV rays out? Is it a different type of UV light? So many questions!

 

[poconojoe]

Try to contact the manufacturer of the one you have. You might get lucky and they might have a solid warranty. They may send you replacement parts.
Mine is made by Tetra and there was water intrusion into the glass tube (they call it a crystal I believe). Luckily the electrical parts were fine. I emailed them and even though my device was 3 years old, they sent me a replacement glass kit with o-rings absolutely free.
Even if you had to pay for the parts, you'd still be ahead of the game financially.

 

[poconojoe]

Another thought on whether to use a UV light or not....
I'm conducting an experiment. My plants, especially the floating ones are not doing so well this season. The water lettuce, hyacinths, sensitive plant and spangles just don't look well.
In the beginning of this season I repaired my UV light setup as stated in the previous post, including a new lamp. It's been on now for a couple months. Yesterday I unplugged it, thinking that maybe it's killing too much and starving the plants.
Time will tell, I guess.
If my plants flourish in the near future, would the UV really be the culprit or would it be a coincidence?
Bottom line, and just my opinion, as long as you have plenty of plants that are thriving, you probably don't need a UV light.
Maybe the light is useful in areas where we have to basically restart our ponds after a cold winter. This is a time when the plants are not active enough to control the algae which results in green water.
So, for now on, I'm only going turn on the UV if the algae gets out of control. Then as soon as the water clears, turn it off. This is my deduction and plan.

 

[Lisak1]

Maybe the light is useful in areas where we have to basically restart our ponds after a cold winter. This is a time when the plants are not active enough to control the algae which results in green water.

But then I would ask if you really WANT to kill that algae as it is obviously serving a purpose in the pond in the early spring. And honestly, we've never had green water in our pond in zone 5B - winters get cold, plants start slow (especially this year!). I know that the thought is that we don't want to wait weeks to enjoy our ponds and clear water, but maybe there are other factors that can be addressed: reduce the fish load? Plants that kick in gear earlier? More aeration? Better fall clean up? (Just thinking out loud here!)

 

[poconojoe]

But then I would ask if you really WANT to kill that algae as it is obviously serving a purpose in the pond in the early spring. And honestly, we've never had green water in our pond in zone 5B - winters get cold, plants start slow (especially this year!). I know that the thought is that we don't want to wait weeks to enjoy our ponds and clear water, but maybe there are other factors that can be addressed: reduce the fish load? Plants that kick in gear earlier? More aeration? Better fall clean up? (Just thinking out loud here!)

Yep, I'm in 6b and every spring I get green water. That's pretty normal from my experience.
Last year it stayed green all season. I definitely have too high a fish load. This spring I lost 2 big koi (both were over 24 inches in length). So, that unfortunate occurrence helped with the fish load.
Plenty of aeration and water movement. I'm guessing the new UV bulb helped clear the water this spring. As I said, I turned it off now and hoping the plants will keep it clear.

 

[Shalmaneser]

I'm planning to expand to ~2500 gallons next year....SO...

I ordered this beast https://www.homedepot.com/p/Alpine-...ION_BOSS_STH-_-Product_URL__WA65336437withTHD

If I don't like it, I can return it to the local HD store. I'm going to winter my floating plants to deploy next spring when we warm up. I don't want algae competing for nutrients, so I'm going to take a crack at controlling the spring bloom.
Currently I'm looking at options for DOC skimmers. Two pop bottles, a couple of suction cups, a bit of PVC, a fine bubble stone and voila! Of course no on wants to look at dat... Then there's the guy who's running a home brew 12" industrial sized skimmer.