What size UV?

[Dave 54]

Koiguy69 I was talking non submersable filter , I keep forgetting many of the ponds on this site are rigged up this way .
You are indeed correct as thats the way our QT system is laid out, however UV-C s are meant to be run 24/7 365 days a year...
We use the double bulb U/V-C and they only last the 2 years before they need replacing loosing half their power in a year poof of this was when I forgot to replace ours and ended up with a green pond, so I now diligently change them in the spring every 2 years.

rgrds

Dave

 

[koiguy1969]

wow... some editing is neccessary on my last post.... that should read 9 watts, not "( watts." and "you should plumb a U.V after a pressure filter." my keyboard batteries must be getting low.
and my filtration is external...i just run a prefilter, before my pump to trap solids before clogging my pump or getting pureed into poop soup and sent to biofilter... but my filter is a DIY upflow waterfall box (SKIPPY STYLE) and the water returns to pond, via a weir,or spillway (gravity flow) ..not tubing under pressure. a U.V would restrict flow and cause filter overflow!!
and YES, my U.V still works... i only run it about 10 days a year. So in 6 years its got 60 days or 2 months use!!! bulbs are rated in hours. mine is rated about 9000 hours. or 8 months.of use then they start loosing effectivenmess.
A U.V only needs to be ran 24/7/365 if your using it for sterilization, "parasite and pathogen control"... on a unplanted formal koi pond yes..on a garden pond with koi as a clarifier, or "just green water alge control"....not neccessarily, once the single cell alge is dead,& green water gone, no need to run it. my water remains clear all season.

 

[slyman]

This is just the thread I was looking for. I have a small 450 GL pond with a Pondmaster 3200GPH pump going to my waterfall. I know for the size of my pond I don't need a lot of wattage, but do I have to get one big enough to handle the pump output? My plan would be to cut the 1.5 inch line going from the skimmer to the water fall and install it in-line. Would that be the correct way to install it? I had one on my last pond but it was in a Savio skimmer, so it was so easy. I miss that skimmer. Thank you.

Bob

 

[crsublette]

I think there is a misunderstanding in that folk think pond volume determines the UV size and wattage. This is not correct.

Pond flow rate is what determines the UV's size and wattage and effectiveness.

Flow rate alone does not determine if the UV is a sterilizer. The strength of the UV light spectrum is what matters when talking about being a sterilizer to kill pathogens, virus, and parasites. Here is a thread, from AquaticEco about sterilizers, that talks more about what is needed to make a UV into a sterilizer.

The diameter of the UV pipe matters as well. UV light can penetrate water as deep as three inches. So, eventhough a 1" flow of water through the UV works fine, you will get the most bang for your buck with a 3" flow of water through the UV.

How do I choose my UV ?? This is a tough subject since there is no easy way to talk flow rates without metering the water, but you can take a rough guess by looking at your pump's flow rate, do some head/friction loss calculations, and then determine your actual flow rate. When properly installed, the single cell pea soup algae should clear within around a week or sooner; so, if this has not been achieved, then slow the flow rate of water with a valve prior to the UV.

For the UV to be a sterilizer with the proper light strength, then the flow rate is approximately 10~20 gph per UV watt rating. So, for a 9 watt UV to be a sterilizer, assuming it has not lost any of its light strength, then the flow rate should be around 90~180gph through this UV.

UV is a sterilizer when it attempts to obtain a 90~100% kill rate of everything in the water that passes by the light.

UV is a clarifier whenever it obtains a much lower kill rate. A kill rate just long enough to kill the single cell algae and I don't know what this kill rate would be to accomplish this.

From reading folk's testimonials, it seems a flow rate of anywhere between 50~100 gph per UV watt rating is enough, but, ultimately, this is told to you by the manufactuer's product flow chart. Although, I have seen the flow rate being anywhere from 40~120gph per UV watt rate, but some folk seem to do just fine with a higher flow rate although it might take longer to obtain the results they desire.

The two brands I highly recommend, due to other professionals that I know who use them, are Evolution Aqua evoUV and Emperor Aquatics. Often times, the more profesional pond hobbyists will have multiple UVs, either multiple 55watt or multiple 110watt, units in parallel so they can significantly improve their flow rate.

Ultimately, choosing your UV depends on your flow rate and what type of flow rate you want to have while effectively using a UV.

 

[crsublette]

This is just the thread I was looking for. I have a small 450 GL pond with a Pondmaster 3200GPH pump going to my waterfall. I know for the size of my pond I don't need a lot of wattage, but do I have to get one big enough to handle the pump output? My plan would be to cut the 1.5 inch line going from the skimmer to the water fall and install it in-line. Would that be the correct way to install it? I had one on my last pond but it was in a Savio skimmer, so it was so easy. I miss that skimmer. Thank you.

Bob

There seems to be a debate on if an inline UV is more effective or if a bypass for a UV is more effective. I say it depends on the convenience of the owner since what matters is to make sure the flow rate is correctly matched with the UV to accomplish what you want it to accomplish.

For a 3200gph pump, with I imagine there is some flow rate loss due to friction and head loss, then the actual flow rate is likely lower than 3200gph unless your pump has a high head height ability. So, assuming there is no flow rate loss, then, for the UV to be a clarifier that is around 50~100 gph per UV watt rating, then a 32~64 watt UV might work for a flow rate of 3200gph, but I would follow the manufacturers recommendation whenever you do choose a UV device. This is just to give you a starting point.

If you want to create a flow bypass to use only half of that 3200gph flow rate for the UV, then a UV clarifier for a 1600gph flow rate would around 16~32 watt UV. Again, I would follow the manufacturers recommendations whenever you do choose a UV device since it also depends on the UV's light spectrum and how it is built. This is just to give you a starting point.

 

[Gags]

My pond is a wildlife pond , it's around 12000 litres...what size UV would I need just for algae control not sterilisation...?

I have a wildlife pond with biofilter installed and want to enjoy the wildlife...I have hundreds of newts and fear I'll get green water as my plants are not established yet as I built the pond last October so it's only 7 months old...

 

[ShawnInfirmity]

Based on my limited research you should be okay with an 18-watt UV for your sized pond. I have a 450+ gallon above ground pond and my 9-watt UV is rated for 1800 gallons. The only reason I went with that one as opposed to the smaller one that is rated for 660 gallons is because the smaller one wouldn't have worked well with my 1000 gph pump.

What ever you decide to do just make sure your UV filter is compatible with your current pump configuration or better yet just put the UV filter on it's own pump/circuit separate from your other filtration.

 

[Gags]

Based on my limited research you should be okay with an 18-watt UV for your sized pond. I have a 450+ gallon above ground pond and my 9-watt UV is rated for 1800 gallons. The only reason I went with that one as opposed to the smaller one that is rated for 660 gallons is because the smaller one wouldn't have worked well with my 1000 gph pump.

What ever you decide to do just make sure your UV filter is compatible with your current pump configuration or better yet just put the UV filter on it's own pump/circuit separate from your other filtration.

Ok thanks for the info friend

 

[Magzire]

Is there any benefits to keep it running if water is already clear?

 

[Jhn]

If you are going for a wildlife pond, why run a Uv? You are establishing the base of the food chain with new pond syndrome ie green water and the zooplankton that feeds on it. Running a Uv circumvents this. The green water will disappear naturally and once your plants are established will most likely not return at all if the pond is set up properly ie enough plants and proper circulation.

Also, Gags you will get more attention to your post if you create a new one rather than piggyback onto a 5 year old one.

 

[I w c]

My uv light is fitted before the filter because all the dead algae spores are filtered out .Why would I want to have the uv light after the filter and put all the dead spores back in the pond?

 

[Lisak1]

Very very old thread here @I w c - and honestly I think you'll find many here have moved away from the idea of an UV filter at all. The single celled algae are killed by the UV but so is every other single celled organism that passes by. But if this set up is working for you, then great!

In theory I agree with you - dead algae in the pond only feeds more algae.

 

[j.w]

@I w c

 

[hammer]

I have a 6000gph pump with a 4000 aqua II filter..... I'm considering a 4000gph UV but oh my gosh the cost of an aqua II UV wiper is like $1000