UV Size Advice

[dangles]

So I'm about to build a system with a 120 gallon tank, and a 40 gallon sump, so a total system of 160(ish) gallons. I had planned to get a UV sterilizer and originally was going to go with a 25 watt Aqua UV, which is rated for 160 gallons.

Since I'm RIGHT at the upper limit for that unit, should I just go with the next size up? I think it's the 57 watt 40 watt.

My plan is to have it plumbed inline and ready to go on an "as needed" basis (bacterial outbreaks, new fish additions, sick fish, whatever). So it won't be running all the time.

Thoughts?

 

[blaxsun]

The next size up would actually be 40-watts, but since the 40-watt is a tad bulky I might be inclined to go with the 57-watt (this is what I run on my 200-gallon system). Order a spare bulb for it right away when you get it.

Either run the UV 24/7 or don't run one at all. Running it "part" of the time is only going to give you some benefit and won't necessarily help any sick fish.

 

[YOYOYOReefer]

get The 40

 

[Sleepingtiger]

The next size up would actually be 40-watts, but since the 40-watt is a tad bulky I might be inclined to go with the 57-watt (this is what I run on my 200-gallon system). Order a spare bulb for it right away when you get it.

Either run the UV 24/7 or don't run one at all. Running it "part" of the time is only going to give you some benefit and won't necessarily help any sick fish.

this. make sure you dial in the flow correctly is the only thing i will add.

 

[dangles]

this. make sure you dial in the flow correctly is the only thing i will add.

Ok reading through Aqua UV's manual, with a 25 watt unit I would need to set flow between 400 and 1200 gph depending on what I'm targeting. Lower flow rate (higher UV dose per-pass) for larger pathogens like fish parasites, and higher rate for smaller pathogens like bacteria...

With the 40 watt unit I would need MUCH higher flow to achieve those goals - roughly 1000 gph for parasites, and 3000 gph for bacteria. There's no way I can hit that high end after head pressure with the Vectra M2 I'll be using.

If I'm interpreting that right, wouldn't getting a larger-than-needed unit tie my hands on what I can actually target? In other words, my ability to provide the necessary flow will be the limiting factor to which UV unit I get won't it?

 

[Sleepingtiger]

Ok reading through Aqua UV's manual, with a 25 watt unit I would need to set flow between 400 and 1200 gph depending on what I'm targeting. Lower flow rate (higher UV dose per-pass) for larger pathogens like fish parasites, and higher rate for smaller pathogens like bacteria...

With the 40 watt unit I would need MUCH higher flow to achieve those goals - roughly 1000 gph for parasites, and 3000 gph for bacteria. There's no way I can hit that high end after head pressure with the Vectra M2 I'll be using.

If I'm interpreting that right, wouldn't getting a larger-than-needed unit tie my hands on what I can actually target? In other words, my ability to provide the necessary flow will be the limiting factor to which UV unit I get won't it?

that flow rate of 1000gph is way too high for parasites

for my 90w UV, i am running around 400gph for parasite control. For a 40w UV, i wouldn't run it faster than 250gph. This isn't me guessing, its based on the specs of the UV and the research done by experts to calculate the contact time to kill parasites.

 

[dangles]

that flow rate of 1000gph is way too high for parasites

for my 90w UV, i am running around 400gph for parasite control. For a 40w UV, i wouldn't run it faster than 250gph. This isn't me guessing, its based on the specs of the UV and the research done by experts to calculate the contact time to kill parasites.

I got those rates directly from Aqua UV's user manual. Can you post the source for your info?

 

[blaxsun]

I got those rates directly from Aqua UV's user manual. Can you post the source for your info?

Most of us run less than the recommended 1,066GPh for parasites on the 57-watt. This increases UV radiation and exposure such that we're getting close to "kill" levels for parasites as opposed to just "sterilization". I'm running somewhere between 500-650Gph on my 57-watt.

There's several threads on R2R that have discussed radiation levels, with most suggesting levels higher than 135,000 for effective parasite control (I don't have any links, sorry).

You'll be fine with a flow rate of 1,000Gph. You'll also be fine with running half of that.

 

[SPS2020]

Do a few searches on here; there's lots of very specific info relating to your inquiry including contact time, etc. I would go for the highest power within your budget. I have a 57watt on my 100g and a 40watt on my 60g.

 

[dangles]

Most of us run less than the recommended 1,066GPh for parasites on the 57-watt. This increases UV radiation and exposure such that we're getting close to "kill" levels for parasites as opposed to just "sterilization". I'm running somewhere between 500-650Gph on my 57-watt.

There's several threads on R2R that have discussed radiation levels, with most suggesting levels higher than 135,000 for effective parasite control (I don't have any links, sorry).

You'll be fine with a flow rate of 1,000Gph. You'll also be fine with running half of that.

I've wondered about that! I had never heard that "UV just keeps things from reproducing, it doesn't kill." The reef hobby was the first time I've ever heard that idea.

As far as I understood, UV DOES kill. We use it in the hospitals to KILL viruses in contaminated rooms, and UV sterilizer pens are used to KILL bacteria/viruses in contaminated drinking water.

I wonder if whoever started that idea was using the wrong definition for the word "sterilize"...

Anyway, thanks for all the help.

 

[blaxsun]

I've wondered about that! I had never heard that "UV just keeps things from reproducing, it doesn't kill." The reef hobby was the first time I've ever heard that idea.

As far as I understood, UV DOES kill. We use it in the hospitals to KILL viruses in contaminated rooms, and UV sterilizer pens are used to KILL bacteria/viruses in contaminated drinking water.

I wonder if whoever started that idea was using the wrong definition for the word "sterilize"...

Anyway, thanks for all the help.

UV does kill. In the reef environment is mostly sterilizes, though (unless you run it at much higher radiation levels). Sterilization is often enough in most instances. Some of just like having our phasers "set to kill".

 

[brclark82]

I got those rates directly from Aqua UV's user manual. Can you post the source for your info?

FWIW, Pentair (I know you aren’t looking at Pentair but they give better recommendations) recommends a max 262gph with a suggested 157gph for parasites/bacteria in their 40W unit and this is from a ton of research. I know it’s a different brand and amount of time spent in each unit may be a bit different but I would go around 200gph in a 40W unit if it were me

 

[brclark82]

180,000 uw/cm is recommended for Protozoa which is double the largest column Aqua UV advertises so take half the flow rate of the far right column and that’s where you should be…maybe around 480goh for the 40W

 

[theatrus]

The limiting factor for UV slow flow rate is getting too warm, remember that you’re basically strapping a 25/40/57/80W heater to your tank 24/7. The UV needs some flow to not actually cook its self, but that can be pretty slow.

 

[YOYOYOReefer]

I got those rates directly from Aqua UV's user manual. Can you post the source for your info?

You missed something ….See the part where it goes from 150 gallons to 325.
So double the flow need to adjust for tank size to be apples to apples
950/2 =450 gph in the same 150.

 

[YOYOYOReefer]

And I agree with the others you probably want less if your tanks smaller than a 150