Can your UV sterilizer be too big?

[kruler]

I am currently setting up a Reefer 425XL (112 gallon total system volume) and would like to plumb in a UV sterilizer primarily as preventative for algae/bacteria/dinos but it would be great if it also prevented fish parasites. I have watched the BRS videos and read the threads I could find and I am still left confused regarding proper sizing of the UV unit. The units I'm looking at are the Aqua Ultraviolet Classic 25W or 57W or the Pentair 25W.

I plan to plumb the UV in line after the return and expect that it will have in the neighbourhood of 450-500 gph of flow through it. Based on what I have read, this is likely the max due to being restricted by the stock Redsea plumbing. This results in turnover of about 4.5-5 times per hour.

Now Aqua UV's sizing chart indicates 30,000 units/cm2 for bacteria/algae management and 90,000 units/cm2 for protozoa. It also says "Reef Tanks -A UV rated in the 30,000-45,000 columns is ideal for the reef environment .UV’s rated at higher kill rates will destroy the planktonic food supply for the reef." This is the only place I have seen any mention of a potential downside of having "too much" UV in a reef tank. Based on what I have read, it seems many people run the protozoa UV levels in reef tanks.

The Pentair sizing chart indicates 180,000 units/cm2 for protozoa or double what Aqua UV says. They don't make any mention of risk to the planktonic food supply.

The charts say that the AquaUV 25w is good for up to 150 gallons and recommends a flow rate of 400gph for 90,000 units. The 57w version is good for up to 355 gallons and achieves 90,000 at 1,066 gph. The Pentair 25w recommends 472gph for 30,000 units and 79 gph for 180,000 units. I would not be able to achieve 180,000 with the Pentair as I could not have the flow that low and if I could, I would not have the turnover necessary to be effective against algae. The Pentair unit is also larger and will be more challenging to fit in the stand.

I was leaning toward the AquaUV 57w and thinking that if I ran 450-500gph through it I would be getting 180,000 units and also 4-5 times turnover, thereby being effective against algae/bacteria and also protozoa. I would appreciate some insight on whether there are actual downsides to oversizing a UV and if there is anything I'm missing.

 

[DeniableArc]

I’m interested as well. I put a 18w on my reefer 250 a while ago with 750lph flow around 3x turnover and it definitely helped with Dino’s

 

[DeniableArc]

I’m interested as well. I put a 18w on my reefer 250 a while ago with 750lph flow around 3x turnover and it definitely helped with Dino’s

On the instructions it says max 6000lph flow but it’s for a pond

 

[Badilac]

The bigger it is the more heat it produces. I run the Lifegard Pro-Max 90watt in my 300 system, but I also ran it on my IM112. That tank went from not needing a heater at all to needing a chiller with the pump and UV online.

 

[brandon429]

There is no harm for killing planktors, thousands of nano reefs have been doing 100% water changes for twenty years now, retail feed replaces all lost plankton, live rocks keep producing it

 

[ca1ore]

The bigger it is the more heat it produces. I run the Lifegard Pro-Max 90watt in my 300 system, but I also ran it on my IM112. That tank went from not needing a heater at all to needing a chiller with the pump and UV online.

I agree that's really the major issue with dramatically oversizing. There was a thread recently where a chap could not understand why his tank temp was rising when adding an UV. UV was 40w and the submersible feed pump 105 …. that's like adding a 150 watt heater that stays on all the time.

 

[Badilac]

I agree that's really the major issue with dramatically oversizing. There was a thread recently where a chap could not understand why his tank temp was rising when adding an UV. UV was 40w and the submersible feed pump 105 …. that's like adding a 150 watt heater that stays on all the time.

Absolutely correct.

 

[kruler]

I had not thought about the heat. This would probably be an added concern with running the 57w at only ~450gph since there would be more contact time with the UV. However, it might not be a concern at all because it would just mean my heater would not work as hard.

 

[ca1ore]

This would probably be an added concern with running the 57w at only ~450gph since there would be more contact time with the UV.

That actually makes very little difference. You either have more water coming out at a lesser temperature or less water coming out at a higher temperature. Total added heat is the same ...... if one believes in the laws of thermodynamics. It may actually be that running slower means less heat added to the tank if the UV housing radiates more heat to the air. Probably minimal and likely overthinking it LOL.

 

[Miller535]

I wonder if pointing a fan at the uv would help, if it started raising the tank temp too much.

 

[kruler]

That actually makes very little difference. You either have more water coming out at a lesser temperature or less water coming out at a higher temperature. Total added heat is the same ...... if one believes in the laws of thermodynamics. It may actually be that running slower means less heat added to the tank if the UV housing radiates more heat to the air. Probably minimal and likely overthinking it LOL.

That makes sense. Thanks for the physics lesson.

 

[Badilac]

I had not thought about the heat. This would probably be an added concern with running the 57w at only ~450gph since there would be more contact time with the UV. However, it might not be a concern at all because it would just mean my heater would not work as hard.

What size heater do you run? You will need to see the power consumption on the pump you plan on using and add that to the UV's power. You may end up being higher than your heater. Also keep in mind your heater probably doesnt run 24/7 like the UV will.

I wonder if pointing a fan at the uv would help, if it started raising the tank temp too much.

No it will not. If the unit is consuming power it is creating waste which is heat. The heat is transmitted to the water. The body of the UV doesnt get hot.

 

[Miller535]

What size heater do you run? You will need to see the power consumption on the pump you plan on using and add that to the UV's power. You may end up being higher than your heater. Also keep in mind your heater probably doesnt run 24/7 like the UV will.

No it will not. If the unit is consuming power it is creating waste which is heat. The heat is transmitted to the water. The body of the UV doesnt get hot.

Oh, Ok. I have never had a UV and assumed the bulb would make the housing hot.

Me personally I live in Pennsylvania and my heaters run A LOT. So I can't imagine it making enough heat to matter. Except for maybe 2 months a year.

 

[LDog74]

The bigger it is the more heat it produces. I run the Lifegard Pro-Max 90watt in my 300 system, but I also ran it on my IM112. That tank went from not needing a heater at all to needing a chiller with the pump and UV online.

I am looking at the Lifegard Pro-Max 55watt vs Pentair Smart UV 40watt for either Waterbox 220.6 or the Red Sea XXL 900. How do you like the Lifegard? Any input on either?
Thank you!

 

[kruler]

What size heater do you run?

I'm planning on running 2 x 200w

 

[ca1ore]

That makes sense. Thanks for the physics lesson.

LOL …. wish I could help my kids with their physics questions ….

 

[Badilac]

I am looking at the Lifegard Pro-Max 55watt vs Pentair Smart UV 40watt for either Waterbox 220.6 or the Red Sea XXL 900. How do you like the Lifegard? Any input on either?
Thank you!

Here is a summary that I posted else where on my Pro-Max.

I run a Lifegard Aquatics Promax 90watt on my 300+ system and I have no issues with it. High quality, all replacement parts are available, has replaceable PVC liner unlike most units on the market. The power supply also has a count down day meter (kinda of like a reverse hour meter) that lets you know when its time to service the unit. I also really like how the input and outputs can swivel which makes the mounting and plumbing options extremely flexible. My 90 watt unit pulls 85 watts per my Apex.

Aquarium, Pond & Water Garden, Fountain and Commercial Aquaculture Products – LIFEGARD® AQUATICS » Product Detail

https://www.amazon.com/Lifegard-Aqu...s=lifeguard+aquatics+uv&qid=1583495672&sr=8-2

Yearly maintenance will cost $84.82 which includes the PVC liners, 90 watt UV bulb, gaskets, and O-rings. Compare this to the Aqua UV unit in which the 40 watt bulb is $86 alone and doesn't have replaceable liners. Same can be said for the Pentair units, no replaceable liners, although there 40 watt bulb is only about $67. Also keep in mind I am comparing the Lifegard 90 watt Pro-Max to the maintenance cost on the competitors 40 watt units (most popular on bigger tanks) just to show you can get more for the same.

So basically you can get a quality unit for less initial cost, less yearly cost, more serviceable and double the UV output from Lifegard when compared to the other popular units like Pentair or Aqua UV. Lifegard also has a 120 Watt unit if you want more POWA! although the cost is $250 more than the 90 Watt unit.

So basically yes I like it. Some of that doesnt pretan to your questions it was easier for me to just copy and paste.

 

[Mattman1977]

I hope you can’t get one to big. I have a 55 watt on a 24 gal nano cube. Only runs 2 hours a day one hour after lights off and one hour 6 hours after lights off. Otherwise as stated it will heat up your water. Really just there tp make me feel better but know I can kill anything water borne in the tank

 

[Badilac]

I hope you can’t get one to big. I have a 55 watt on a 24 gal nano cube. Only runs 2 hours a day one hour after lights off and one hour 6 hours after lights off. Otherwise as stated it will heat up your water. Really just there tp make me feel better but know I can kill anything water borne in the tank

Don't know the truth behind it but in the BRS UV video they said if you aren't gonna run it 100% of the time you shouldn't even run it at all.

 

[Mattman1977]

Don't know the trust behind it but in the BRS UV video they said if you aren't gonna run it 100% of the time you shouldn't even run it at all.

Depends on what you are trying to kill. I had a slight Dino outbreak that I couldn’t get rid of that went into the water at dark. Dino is now under control. But I did buy it so big to put it on my larger tank after I get it set back up. Getting new floors. I mean look at that sexy carpet.