UV Sterilizer question

[Pike614]

Hi,
I've got a 450g reef and would like to upgrade to a larger UV sterilizer for the tank. I would like to know if using several UV sterilizers, like the turbotwist 12 x 36 watt units...would be the same as one bigger unit. For example. Would an 80 Watt Aqua UV unit provide the same results as 2 of the 36 watt turbotwists mounted in line with each other?
IN the end the total watts is close, but I am not sure if UV works like that. Any input will help!
Thanks!
Paul

 

[Marinworld]

No it would not work that way. The UV's are both 36 Watt, so you're getting only 36 watts. In other words, two 36 watt bulbs are not as strong as (1) 80 watt.

Good Luck
Don

 

[luther1200]

Why not? If you theoretically had 2-100w MH wouldn't they put out as much light as a 200w? So why would it be different for that? I think the only reason they make different sizes is to accomodate different size tanks. It doesn't have anything to do with how well they work. In other words you wouldn't need an 80w for a 75g, but yhou would for a larger tank. So instead of having multiple small UV's they make bigger ones. But if you wanted multiple smaller ones, I don't see why it would matter, IMO.

 

[Pike614]

Ok, the 36 watt was just an example. I thought that maybe for example two 40 watt units would not have the same exposure time compared to a 80 watt unit with two bulbs....so since I already have a 36 watt unit, if I add on an aqua 57 watt unit then it'd basically be equal to a 93 watt unit?

 

[Marinworld]

PIKE64

The two units inline that are the same watts would not double the intensity of the UV. It is still 36 watts. Remember the water is moving, it's not sitting in one spot. One 72 watt UV would have more intensity into the water at the time of contact, or, the period the water passed by the UV. One stronger unit would therefore be better than 2 smaller output units.

LUTHER1200

Your Metal Halide example is not the same in theory. You are comparing 1 Halide of lets say 250w to 2 Halides of 125w. This would produce the same strength because the halides are sitting over a large cube of water. That cube is recirculating in a given area x by x by x, however
the cube itself is not flowing past the Halides in a steady stream. The water is constantly on a linear pass through the tubing.

Regards
Don

 

[pbaldwin]

What are you trying to accomplish with the bigger UV?

If its a desire to treat more of you tank water per hour then yes adding a second unit in parallel to the first would do that for you.

If you want to add the second light in series then assuming that you have your flow rate already properly adjusted all you would be doing is shining a light on already sterilized water.

 

[GT3000XX]

Marinworld is correct. You will have a longer contact time running 2 in series but you will not have the intensity a single higher wattage UV would give you.

 

[unhpian]

There is some serious misinformation going on in this thread . .

pbaldwin
"If you want to add the second light in series then assuming that you have your flow rate already properly adjusted all you would be doing is shining a light on already sterilized water."

Thats not true - UV units used for aquariums are very low power - and you are not even coming close to a 100% kill rate. What makes these practical for aquariums is that the water is circulated many times per hour - and even if each pass only kills 5% or organisms, the cumulative effect over many hours is a much higher kill rate. If you want a something close to a 100% kill rate, I'm working with a 10 kwH lamp at the moment in our lab, and even that only reaches about 95%. For comparison, the 35 watt bulb we're talking about in this thread is a 0.035 kWH bulb.

Marinworld
One stronger unit would therefore be better than 2 smaller output units.

Nope. All things being equal, A 70 watt unit would provide the same disinfection as two units 35 watt units in series. Why? It's all about dosage.

With disinfection (and this includes algae), the most important parameter is DOSAGE. Disinfection dosage is based upon concentration*time - also known at Ct. If you increase either the concentration (in this case, UV intensity), OR exposure time, the effective disinfection dosage will increase. If you double the exposure time (by adding a 2nd unit), your exposure time will double, effectively doubling your disinfection dosage - So, if your goal is to increase your disinfection rate - then two UV units in series will do that. Think of it this way - If you are taking antibotics, and you can either take one 1,000 mg tablet, or five 200 mg tables, either way, the dosage is the same.

 

[luther1200]

Right, so the only reason they make different sizes is to accommodate larger and smaller tanks, correct?

 

[Marinworld]

Unhplan:

Actually the formula to find the ZAP DOSAGE is:

Intensity, I, is the units of microwatts per square centimeter, and time, t, can be measured in seconds, the dose, D, is given by:

D=I x t[microwatt-sec/cm2]*

I stand corrected, in the example that I used. However, if the two units in series were of a lesser combined intensity than the single unit used, the Zap Dosage would then favor the single unit of higher intensity.

Your thoughts,
Don


*Aquatic Systems Engineering: Devices And How They Function
P.R. Escobal

 

[Pike614]

Wow, lots of great information. Thanks everyone! I conclude then that two 40 watt units mounted inline would be the same as one 80 watt unit then. I have a TurboTwist 36 watt unit and plan to add on an Aqua unit. I was hoping to help control free floating parasites, so I need a slower flow rate. All of your input helped!
Thanks!