UV Sterilizer

Falcar

New member
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Hey all:

I got a nice deal on a UV sterilizer that is oversized for my system. It is a Pentair SmartUV 40w. I am building a 125g system right now that I plan to use it on.

I'm wondering how much heat do one of these typically add?

Also from a new system perspective, when do you start using them? Right away or?


Thanks in advance!
 

Humblefish

Dr. Fish
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Do you plan to run it at a faster (to kill algae spores) or slower (to kill parasites) flow rate? If the latter, then I doubt it will add much heat to your system. I've sometimes seen a degree or two uptick (in smaller systems) when using a UV for water clarity / algae control purposes.

I wouldn't turn it on until the tank is fully cycled i.e. any nitrifying bacteria you dosed into the water has seeded the rocks & sand.
 

Falcar

New member
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I plan to run it faster for algae reduction, as hopefully my parasites will be avoided through QT.

Ok I'll hold off on turning it on until things get going.
 

mggray87

Dino man
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That's not oversized at all. I have a 57w for my 110g of water or so
 

mggray87

Dino man
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Any decent pump 300 plus u won't see any heat issue. Won't even know it's there
 

Badilac

Active member
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I run my 90w on my 300+ system at a fast rate and it for sure heats my tank. so it really all depends on conditions and type of other equipment. if running all DC pumps you may be OK. On my 150 system the same 90w UV was the sole reason I needed to purchase a chiller. Without the UV my heaters cycled on and off throughout the day once I added the UV the heaters were no longer needed and I had to purchase a chiller.
 

clsanchez77

20 Year Noob
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The heat put out by a UV has nothing to do with the flowrate...40 watts is 40 watts. UV's are very inefficient light-wise, so I would just assume all 40 watts is heat to be safe.

Now having said that, flowrate will impact the final temperature of the water coming out, but the total thermal mass will be the same at the end of the day. This will be counter-intuitive to most and that is fine. Thermodynamics was the only class I almost failed in engineering school :D But I understand it now and if you want a detailed explanation, I can certainly provide it.

But to answer your question as asked...a 40W UV unit will put out almost 40 watts in heat....which corresponds to 136 BTU/hr or 0.05 (1/20) hp, regardless of the flowrate.

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Now, is this something to worry about? No, 40W on the systems we run today is nothing. We can't even maintain tank temps with a 40W heater, so I would not worry about this. Most of this heat will be lost through your tank walls if the aquarium is warmer than the room it is in and through some additional evaporation, and not very much more. In the winter time, this will give your heaters a slight boost, but I would not downsize heaters over this.
 

Bruce

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Would an aqua 57 watt be enough for a 205 gallon tank? I want to use it at a slower pace to kill parasites
 

clsanchez77

20 Year Noob
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I think you might be a little thin on a 205 gallon. What brand? The dosage rate per watts is not the same for all brands as it depends on the reaction tube diameter and length.
 

clsanchez77

20 Year Noob
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I have the Aqua 57 watts
Cool, pricey but I like that brand. At 90,000, they recommend a flow rate of 1,066 gph. Dosage rates are not well documented for marine parasites, so I would rather push for 180,000, which is recommended by other manufacturers. The flow to dosage is linear, so set the flow to 500 gph and you are good.

In contemporary terms, 500 gph is almost a 2.5 turnover per hour in your tank. As a water resource engineer, I HATE this line of thinking as it is not true due to mixing of the water in your DT. Actual tank turnover will be 6 times a day (3.8 hours per turnover) and is wonderful for this task :D

With this UV on this tank, should you get an algae or bacteria bloom, just crank that sucker up for a couple of days to clear the tank, then dial it back down.
 

Bruce

New member
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Cool, pricey but I like that brand. At 90,000, they recommend a flow rate of 1,066 gph. Dosage rates are not well documented for marine parasites, so I would rather push for 180,000, which is recommended by other manufacturers. The flow to dosage is linear, so set the flow to 500 gph and you are good.

In contemporary terms, 500 gph is almost a 2.5 turnover per hour in your tank. As a water resource engineer, I HATE this line of thinking as it is not true due to mixing of the water in your DT. Actual tank turnover will be 6 times a day (3.8 hours per turnover) and is wonderful for this task :D

With this UV on this tank, should you get an algae or bacteria bloom, just crank that sucker up for a couple of days to clear the tank, then dial it back down.
Ok thanks So that size is good enough or too small? I got it used from my buddy however I bought a new bulb for it.
 
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