Can A Uv Unit Be Too Big?

[konakid]

Is it possible to buy too large of a uv sterilizer? I have a 200-250 gal pond and a 400 gal/hr pump on a small waterfall/filter. I have another 400 gal/hr pump that will be running a bubbler/small filter part time, that can also be directed to the waterfall if/when desired. So I could direct 800 gal/hr. through the waterfall/filter when wanted. Would a 25 watt unit be too large? Is it even possible to install a unit that is too large? The in/out on this size is much larger than the 3/4 in. tubing I am using. So on the larger units with a 2 in in/out, the water would be moving much slower than I would think it was designed for. In addition, I was worried that if it is too powerful and immediately before my waterfall bio-filter, could it have any residual negative effect on the bacteria in the filter?

I didn't want to have to run the unit full time. But I wouldn't mind having a powerful unit installed that could be turned on only when/if it was needed due to certain situations (algae blooms or fish illness). I understand it is not a "cure-all" and that other water management practices (plants, water changes, low fish load, etc.) are equally or more important - but I just wanted to make the water quality and clarity as good as possible.

 

[thereverendturtle]

UV sterilizers produce a lot of heat. Should be run continuously. Doesn't matter there placement, UV can't escape. 9 or 18 watts should work well.

 

[Prime Ordeal]

The only time the UV unit will cause a problem is if you ever use a bacteria-in-a-bottle product as it will just wipe the bacteria out. You'd need to give it a few days without the UV to let the bacteria get established in the filter.

 

[TwoTankAmin]

UV does not need to run continuously.

The effectiveness of a unit is a function of several things including:

The bulb wattage.

The contact time (how long water running though the unit is in contact with the UV Light}.

The turnover rate. How long it takes to turn over the volume of the tank/pond.

Other factors of note include:

Design/bulb length.
Clarity of the water.
The quartz sleeve that protects the bulb.

UV can kill free floating bacteria. it will also tend to have a negative effect on meds so should be turned off when medicating.

Knock yourself out and read here: http/www.americanaquariumproducts.com/AquariumUVSterilization.html#whatsize

 

[Prime Ordeal]

UV can kill free floating bacteria.

Will, not can.

it will also tend to have a negative effect on meds

Good point, I'd forgot about that.

 

[Vin Swords]

I run 2x25w on 450l tank.

It play big part in algae control. Feel it ur self.. I use it for years.. Just Don't run the lights with out water.. It will burn the casing.

 

[konakid]

Thanks for the input.

But my main question remains unanswered. Is it possible to have one that is too big?

The main reason I am asking is because my pond is going to be running on a solar pump, so I don't have power out there. So to use it I will need to run an extension cord out there. So I would like to install a unit that is a lot bigger than called for and only run it when/if needed. I figured if it was oversized I could get away with running it for less time, as it may clear things up more quickly than a smaller sized unit. I might add that I will also have a back up pump that I can plug in if the solar acts up or in times of prolonged cloud coverage. In other words, I would also have a means to provide intermittent increased turnover, increased mechanical filtration, along with a good blast of UV from the larger than really needed UV sterilizer. I was hoping that this might allow a shorter duration with an extension cord running out to the pond.

I understand a lot of other factors are in play regarding water quality/clarity. But with all things equal, I was hoping to err on the side of a unit that is larger than called for, in hopes it would limit the time I may need in run it with the extension cord running across the backyard - if in fact I even need to. Due to the installation, it will be much easier for me to plumb one in now than to try and do it later.

But I didn't want to blow it by getting a unit that was too powerful. Is this even possible?

 

[TwoTankAmin]

First-

Will, not can.

Not quite right. Can means it is capable of doing so, will means it does so. If the light is insufficient, the contact time to short etc, a UV which can kill bacteria, won't.

The site I linked provides formulas for calcluation what size unit one need, what flow rate through iy and what wattage. What you need to do is the math based on the wattage basically. It breaks the killing power into 3 categories:
Clarification- which means killing algae spores.
Level 1- which means killing bacteria and some viruses.
Level 2- which means killing parasites and stubborn viruses.

It then indicates how to calculate what flow and turnover rates are needed for each level. Basically, the more stuff one wants to kill, the slower the flow rate through the unit has to be but also the higher the turnover rate needs to be (ie how long it takes to pass the entire volume through the unit.

[font="Arial][size="4"][font="Arial][size="4"]For sterilization (level 1) you want 20-25 gph per watt and an aquarium turnover rate of 1-1/2 times per hour (recommended minimum).
Example: In this example I will use a 100 gallon aquarium;
*For Clarification (Green Water Control; generally the most common application in ponds) you would need a flow rate of 40-50 gph and a turnover of aquarium/pond water through the UV of once per 2-3 hours. So as a minimum you would need a flow rate of 50 gph (assuming once per 2 hours in water turnover). At 50 gph (for turnover) the smallest UV available is a 5 Watt which can have a flow rate up to 250 gph for clarification.

*For Level One Sterilization (generally the most common application in aquariums), you would need a turnover rate of 1.5 times per hour which would be 150 gph for this example. The flow rate through the UV should be 20-25 gph per watt (I will use 20) which would mean 7.5 watts would be the minimum UV Sterilizer (20 x 7.5 = 150).

*For Level Two Sterilization, you would need an aquarium/pond turnover rate through the UV Sterilizer of up to 4 times per hour, which would mean 400 gph for this example. The flow rate in gph per watt is best under 10 (generally even lower, we will use 8 gph per watt for this example), so at 400 gph this would require a 50 Watt UV Sterilizer (or possibly two 25 Watt UVs running at 200 gph each).[/size][/font][/size][/font]

Now you just work with the numbers to achieve the goal. If one wants to spend more money for a more powerful unit, then you can run the system faster and for less total time/day. You can control th flow rate based on what flow rate the driver of the system produces (I use a power head for example but one might use a pump, inline with a filter or any other means to make water flow through the unit you choose.) You have to mess around with the numbers to come up with exactly what you will use.

BTW- Here is what the link I suggested says about your question:

[font="Arial][size="4"][font="Arial][size="4"]Is Too Large a UV Sterilizer a Problem?[/size][/font][/size][/font]

[font="Arial][size="4"][font="Arial][size="4"]This is an occasionally asked question to which the answer is generally no with some exceptions. In my view spending more for say a 36 Watt UV connect with a 300 gph water pump flow will produce 8.33 gph per watt, however this does not generally produce much better results than 20 gph per watt. While it may be true that parasites such as Cryptocaryon (marine Ich), are more readily killed at this rate, this is not an established fact either (as of writing this). I find that UV Sterilizers help control Ich or similar parasites not by killing them, but by improving water quality such as Redox which in turns improves the fish' natural resistance allowing treatments or other measure to eradicate a given parasite infestation.
As well in a marine reef tank in particular, this high wattage to flow ratio may kill copepods or other propagated organisms (assuming they get into the water column, which is rare). While the facts that many of the organisms propagated in marine reef are not killed by typical UV flow rates (20 gph per watt), making it a myth that UV Sterilization should not be used in reef aquariums, I would also not push the envelope with flow rates under 10 gph per watt.

Another aspect to consider with low flow rates per watt (generally under 10 gph per watt), is that I have often found that with commonly used UV Sterilizers that the aquarium turnover rate is affected which is another important aspect of UV Sterilization. With the above example of the 36 Watt UV and a flow rate of 300 gph on a 100 gallon aquarium would not be a problem. However lowering flow rate to 50 gph (so as to maintain 10 gph per watt) with a 5 watt UV Sterilizer would considerably lower UVC effectiveness in this same 100 gallon aquarium.[/size][/font][/size][/font]​

[font="Arial][size="4"][font="Arial][size="4"]This all said, if you do not have a marine reef aquarium, just a fish or plant only aquarium and feel more secure with a flow rate of 10 gph per watt, by all means go for it, but generally this is just money wasted in my experience. ​

Hope that helps.
[/size][/font][/size][/font]​

 

[konakid]

I hope that helps.

Yes it does. Thanks for taking the time. Exactly what I was looking for, and apparently I missed that section on my first brisk read through.