PAR and watts per gallon....

curiousphil

Super Active Member
Joined
Apr 15, 2013
Location
London, Ontario
So I've been thinking about my light situation, and trying to figure out how the intensity of my DIY LED system might stack up against say a MH unit.  Mainly I want to figure out if I need to raise my rockwork closer to the lights or dim my lights further.

In the reading I've done on lighting intensity and 'watts per gallon' I've been led to believe that 4-8 WPG is considered to be a good "high intensity" light for SPS.  I've also read that that is mostly in reference to VHO/T5/MH but not so much LEDs - that people often in fact say they need about .

With my system I'm running 106 3w emitters, ranging from 1000mA on the whites and blues to 700mA on the violets and 500mA on the OCWs.  With an internal tank volume of about 81 gallons that puts me at approximately 3.9 WPG.  My lights are totally ghetto rigged right now sitting on a glass panel that is held on top of the tank via some galvanized steel corner beading, putting them about maybe 3-4 inches above the water.  I have a basic light controller hooked up that provides a constant dimming signal that brings things down to 70-80% intensity (no sunrise/sunset dimming yet - I still need to get the RTC working) and then the whole system is on a timer for a 1pm-9pm photoperiod.  Given all this, *I THINK* I am about on par with a 2x250W MH system.


(If there's one thing you should know about me... it's that I like putting things in context :).)


Now on to my question - all this guesswork is fine and dandy but I think I need to just find out what my PAR is.  Anyone in the area have a meter, and want to come check out my tank in exchange for a few drinks??  If not, I really should get out to see some of the LED tanks in the area (salty!) so that I can get a bearing on how mine looks in comparison.
 

Reef Hero

Super Active Member
Joined
May 27, 2012
Location
Lucan
Par is what you need to measure imo.....and dont forget it changes in diff areas and levels of your tank.....this is why you will see sps at the top and lps at the bottom in mixed reef tanks.....watts per gallon theory really does not make any sense imo....because it oes not take into account too many variables such as types of lights, corals placement, and diff types of corals.....
Salty has some nice growth on his sps from leds!!
 

Salty Cracker

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Mar 10, 2012
Location
Rocky Mountains BC
Definitely sps does better near the top of my tank, although the V (violet) seems to be able to penetrate much deeper.  Basically I find that sps down lower has a slower growth rate, and can get a bit more brown on the undersides, where stuff at the top can bleach if it's not used to the lights. 
 

curiousphil

Super Active Member
Joined
Apr 15, 2013
Location
London, Ontario
Ya understood... I just need to know objectively how bright my lights are!  My rockwork isn't very tall so that's my big concern.
 

Big_Als_London

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Feb 17, 2011
Location
London, Ontario
That Mille you got from me was right at the top of my tank which is 600 par if I recall.  Part of the browning could be because of the different lights and not acclimating properly.  I know when I get new stuff in it doesn't hold the colour and I have to give it about a month to get the colour back.
 
C

copperkills

Guest
IMO u cant purely use PAR to compare LEDs....there is also a PUR value which is the useable portion of the PAR value.  Its kinda like rating speaker efficiency by peak vs RMS.  Google PAR vs PUR.
 

curiousphil

Super Active Member
Joined
Apr 15, 2013
Location
London, Ontario
it would at least be helpful to know what my par is but I will also look into the pur value... That kinda makes sense I like the peak vs rms analogy as my other big hobby is analog stereo...
 

curiousphil

Super Active Member
Joined
Apr 15, 2013
Location
London, Ontario
I moved my rocks around slightly :s I wish I could install a breathalizer on my tank that would stope me from "aquasscaping under the influence" lol.......

sebubutu.jpg
 
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