What size UV?

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My pond will be about 1800 gal. which I plan on turning over once per hour. That 'once per hour' is what the pump will be doing. I will have a DB running to a SC and then to the pump. I will also have a skimmer running to a UV light and then to the same pump. I plan on regulating the flow of the skimmer line with a ball valve. Question is...what should the flow through the skimmer be (per hour). Seems like I need to know this so that I know what UV light to get (15W, 25W, 30W, ???). My brain is telling me I read that info many months back but can't remember nor can I find it again via google search. Can someone point me to a web page that would help?

Thanks,
Randy
 
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We run a 36 watt one for our 1,000 gallon imperial so it cant be one much higher in power than that .

rgrds

Dave
 
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cr8tivguy

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Question- If your UV isn't large enough, will it still work to rid your pond of algae (maybe just not as quickly)?

I have a hard time understanding how the UV system works. Basically, what I know is the water flows over the UV light and the algae and other bad things are neutralized. Anything other than that, I'm ignorant. What is the impact of 'too slow" or "too fast" water flow?
T
 
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UV's have ratings from their manufacture. The "suggested" flow range will kill the algae and bacterias flowing through it, but if you are trying to kill protozoas, they then suggest a slower flow, as low as 15-20% of their typical suggested flow rate.

Size of UV to pond depends on what exactly you want the UV to do.

On our main pond, we are only running an 18 watt Emperor (already had it when we built this pond) ... should be running their 65 watt, but the 18 watt is doing what we want it to do, so no point in changing it,
 
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cr8tivguy said:
Question- If your UV isn't large enough, will it still work to rid your pond of algae (maybe just not as quickly)?

I have a hard time understanding how the UV system works. Basically, what I know is the water flows over the UV light and the algae and other bad things are neutralized. Anything other than that, I'm ignorant. What is the impact of 'too slow" or "too fast" water flow?
T
My understanding is that...the brighter the light (more watts) the more it becomes a sterilizer killing bacteria and such while a lower wattage will just kill the floating algae. If the water flows too fast then then it is not exposed to the light long enough to get zapped. For my setup there is supposed to be a slower flow for the skimmer/UV line than for the bottom drain line and that will controlled via a ball valve. I read somewhere on what % of the overall flow should be run thru the UV but can't find that info now.

All that is from what I have been able to gather and understand so far. I could be wrong on bits of it.
 

koiguy1969

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any U.V is a sterilizer or clarifier. dependIng on wattage and/or on flow rate. for an example...a 9 watt U.V is a clarifier at 1200gph, but at 300gph it can sterilize. as dwell time can accomodate for lower wattage. an 1800 gal pond can be kept clear with a 9 watt U.V. I INTENTIONALLY let my 1200gal pond green up bad every year.then clear it in 3-5 days with my 9 watt Tetrapond U.V.....
NOW,as a clarifier, the U.V is run to clear green water. once accomplished, it can be shut off and even removed from the system. as a sterilizer it's usually ran all season, even when the green water (single cell algea) is gone.. but this is to kill protozoans, parasites, and other pathogens. i run 865gph thru my U.V. when my water is clear, i run the U.V for an additional week or so. then i disconnect , clean, and store it away. till the next year. and my water stays clear all season.. and i've used the same bulb for 6 years.
 

koiguy1969

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randythawkins said:
koiguy1969 - you said what I need to hear. Thanks.
thats NOT to say that you wouldnt be better off with a larger model... an 18 watter. at twice the watts means it should be about twice as effective at the same flow rate. your better off being "bigger than neccessary" than "too small"
 
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So do you guys think is over kill to put a 55W UV on a lets say 650 gallons pond? I'm picking up a brand new Laguna 55W UV for $100 from someone that purchased it and never used it and now is trying to get rid off it so is there such a thing as too much UV light, I'm not planing on running it all the time, just for a week or so and then until the water starts to get green.
Tks.
 

koiguy1969

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A 9 watt U.V is more than adequate for a 650 gal pond... my 1200 gal pond clears in a few days with a 9 watt.... a 55 watter will do a great job. if the price is right, why not?
 
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Great, thanks for the advice, I actually went and picked the U.V today, brand new Laguna 55W for $100, I wanted to install it tomorrow but the wife had other plans so I guess it'll be Sunday, my water is getting very dark right now so I think I'll take a picture to do a before and after installing the U.V.
 
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Dont forget it goes in after your filtration (some folks make that mistake believe it or not).
Ours is 38 watts and it does 1,000 gallons UK with ease it has a two year bulb life span not the one year ....
Properly maintained with the cystle sleave rmoved from time to time to be cleaned on the outside .
Its also an idea to check the rubber seals as well.
Keep it up and it will last you a lifetime.


rgrds


Dave
 

koiguy1969

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DAVE54 .. you cant install a U.V after the filter with a sumersable pump, and gravity return system. my U.V is installed before my filter, and works great. its only ( watts and will clear my pond in 3 - 5 days. i only run it 10 days a year. clear the pond and an extra week for good measure. i take it out of the system clean it, and store it away for the next season. used the same bulb 6 years. a presure filter with a submersable pump. i would suggest using a prefilter as i do. thats an "inpond" mechanical filter before your pump.
 

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