Trying to understand par

[Mcmcoker]

I recently watched a video on vivid aquariums website about par ratings and in the video the guy was measuring par under water in various depths and areas of the tank and his measurements ranged from 200par to 370par. Reason I'm asking this is because I'm looking at getting a led fixture and want to make sure I get a good one. I'm looking at a few on eBay. A 120w and a 165w. No there not taotronics or some of the other fancy ones but it's what I can afford. The 165w says it has a par rating of 28 and the other just says output optimized for par. So I'm a little confused. Can anyone help explain.

 

[bribo12]

I can try, par stands for photosynthetically available radiation. It is basically tells us how much of the light is actually available to be used by the photsynthetic algae in a coral. Usually people will say low light corals can grow with 50-100 par, medium light 100-300, and high light corals needing above 300 to grow. However, most ppl don't have ready access to a par meter so it is hard to determine just how much par a fixture puts out at different depths in the aquarium.

 

[Mcmcoker]

K I think ive got the gist of that part of it. So what's the deal with the two different fixtures I mentioned. One saying 28 par. Am I just getting to hung up on technicalities and should just know that the fixtures should work just fine for coral growth

 

[mr_X]

That can't be right (28 par). You would barely be able to grow anything.
Post a link to the fixture you are considering.

 

[Mcmcoker]

http://item.mobileweb.ebay.com/viewitem?itemId=370857093101&cmd=VIDESC

I knew proper par ranges had to be between 100 and 400 so the 28 par number posted in the description for this fixture is actually why I started this thread. Understand my confusion. Hope that link works

 

[Mcmcoker]

Could it mean 28 par per led. And what do you think it means by 28par for lens can output more par

 

[Mcmcoker]

This is the other one I was looking at. They both seem good for the price. One is 165w but 60 degree lens and the other is 120w but has 90 degree lens
http://item.mobileweb.ebay.com/viewitem?sbk=1&nav=SEARCH&itemId=360756176801

 

[mr_X]

The 165 watt one is way more than you need. The second is the same fixture everyone nick named "Taotronics". I think it's got too many reds in it though. It's going to make your tank look pink. I have one with just 2 red lamps and i ended up covering them, until I get around to swapping them out for blues.
I don't even think you need the 90 degree lenses really.

 

[Mcmcoker]

Ahh so that's the fixture everyone keeps talking about! It seems like everyone here raves about that fixture but I definitely don't want a pink tank and yes the 165w would be way too much I'm sure. If I got it I'm sure I'd have to run it at 70% or less. Did the verbage about par for that one make any sense to you. Both looked appealing to me but I see what your saying about the reds. A broader range of color seems like a good thing for aquarium inhabitants but at the same time I've noticed that all the really spendy led fixtures are just white and blue

 

[Ingy]

On thing about some of these lights is the controller. Most of the Tao units have 55 LEDs each 3 watt, but the fixture is only a 120W light. Why? Because the underdrive the lights. That extends the life of the LEDs as compared to having 40 x 3 watt LEDs driven by the same 120 watt driver. It is actually good quality control.

the 165 W units that I have seen have also 55 LEDs just driven with a bigger driver (power supply), so they could drive the lEDs brighter. But if you kept it at 66% or below, then you would benifit from the same underdriven protection.

 

[Mcmcoker]

Gotcha, think I'm leaning towards the 165w and just running it at a lower setting. Like mr x said I don't want a pink tank and I think the 165w only has two of the reds as opposed to four. Plus it seems like it would be better to run a 165w at a lower setting than 120w at full power

 

[mr_X]

Not quite correct. The 120 watters are not really running at full power, as Ingy stated. These are 3 watt emitters that are not full throttle when at 100%, so you are ok there.
I don't think you need the 165 watt units at all. You could just swap out a couple of the reds for blues. Not that big a deal if you have ever used a soldering gun.
If you keep looking you can find the same thing with a different configuration. BTW, maybe you could contact the vendor of the 120 watters you posted and ask him if he will swap out a few of the reds for you....

As for a broader range of colors being better for aquarium inhabitants, that's not correct either. It's totally a matter of personal preference. either straight blue and white, or multicolored will grow corals just fine.

 

[Mcmcoker]

All good advice mr x, thank you! So in your opinion all things considered you'd go with the 120w and either see if the seller can swap them out or do it myself? And if I have to do it myself where would I get the LEDs

 

[mr_X]

The seller could probably send you some if he won't do it himself, or RapidLED, or ebay...

 

[Mcmcoker]

Great thanks

 

[Gregcoyote]

I have fixtures with red LEDs and they certainly don't turn the tank pink. I personally like the broader spectrum lights.

 

[mr_X]

I have fixtures with red LEDs and they certainly don't turn the tank pink. I personally like the broader spectrum lights.

Well then, buy them, try them, and see how you like the 4 reds

 

[Mcmcoker]

I might just buy the fixture and ask for or buy separately the extra blue LEDs and if I don't like the color swap them out

 

[Gregcoyote]

They should be easy to change out. Mine has two reds and two greens. Frankly, it just warms the colors up a bit, no purpose other than personnel preference.

My main reef is just blues and whites, frag tank has the "full spectrum" lights.