UV sterilizer.... Is it worth it to run?

[Delphinus]

My opinion is a solid "it depends."

Here's my take on it. If nothing else, UV will break down the organic compounds in the water that tend to cause the water to get that yellow tinge to it, and then this can be skimmed out. So if nothing else, a UV *can* polish the water up some. The water will have a noticeably brighter or clearer look to it.

To actually have UV act as an anti pathogenic tool you need a fairly large unit. I have one myself, think it's a 57w unit, that I keep onhand in case I ever get a bad ich outbreak. When I ran it in the past it did help keep it at bay (not a silver bullet, but it did make a difference with fish that had really bad ich and they were able to overcome it in the end). Anything 20w or less is probably not going to work for this although it will still help polish the water.

Like anything however there are pros and cons. For example, the glass tube the light sits in will need regular cleaning (some units have a built in wiper but not all). Like any light, the UV lamp itself will lose intensity and will need replacing. If you run it 24/7 you will probably need to replace it as soon as 6 months. Maybe longer if you don't run it 24/7 but if you're going for the anti pathogen effect I would imagine you need it on 24/7.

HTH

[gregzz4]

I agree with Tony on a lot of points

I find running a UV unit is a lot of 'feel good'
I run mine at a low enough flow to be beyond the 'green algae' control and closer to 'bug' control

I only change my bulbs once a year and, with the Pentair Lifeguard unit I own, will need to change the inner sleeve every 2 years or so as UV breaks down plastics

It's still only a 'bandaid' for a lot of issues and is best used as a water clarifier, with it plumbed into your system after your filtration to be the most effective

There's lots of good info on the web pertaining to UV flow rates
I use the info here for a guide
Specifically, this excerpt:
*As a Clarifier; For Algae Control (Green Water and some Cloudy Water), 40-50 gph per watt is effective to maintain effective exposure for effective UVC sterilization/radiation (depending on model UV’s design).
High Efficiency (High Dwell/Exposure) UV Sterilizers such as the TMC Pond Advantage with long contact time as per the wattage and lamp can easily run as high as 50-60 gph per watt. The even higher efficiency (& dwell time) Pro Clear UV 30 can go 70+ gph per watt.

*As a Sterilizer; Generally for bacterial control (& many virus) a flow rate of 20-25 gph per watt (75-95 liters per hour, per watt), sometimes as high as 30-35 gph per watt for high efficiency UV Sterilizers such as the TMC Vecton UV.

*As a Sterilizer; For single cell parasite control (such as Cryptocaryon) as well as a few “stubborn” viruses, a flow under 10 gph (or even less) is necessary. This is often not 100% for all parasites of this type, so a UV Sterilizer should not be relied on as the sole preventative for these parasites!