Friendly Posted March 22, 2019 Share Posted March 22, 2019 I'm looking for help to understand light wattage and PAR values and apply them against the 12 gallon long and 22 gallon long with the intent to eventually keep something like a clam that needs lots of light. are there rules of thumb to use for calculating PAR values at different depths depending on the wattage of the light being used...or is it more complicated than that? a 12 gallon long is 8" deep while a 22 gallon long is 12" deep, so what will work for the 12 gallon will not work for the 22 gallon. I'm interested in getting the LOOP Marine kit from Current USA, but their model recommendation is based on tank length and since the two are 36" long, I'm suspicious that it may not be good for a 22 gallon. however, if it is strong enough to allow me to have high light livestock, that's good news, as it means I just have to dial it down for the 12 gallon. my questions/concerns clear as mud? Quote Link to comment
blasterman Posted March 22, 2019 Share Posted March 22, 2019 Law of squares. If the light is twice as high then the amount of light hitting the floor is 1/4. Works in reverse. 2 1 Quote Link to comment
Friendly Posted March 22, 2019 Author Share Posted March 22, 2019 doesn't the addition of water change the way the light behaves? Quote Link to comment
Horerczy Posted March 22, 2019 Share Posted March 22, 2019 Yes but not enough really. There's not a substantial loss of light from the water versus air at the depths out tanks typically are. The most obvious way water effects light is the shimmer effect from surface tension and that isnt a big deal. 1 Quote Link to comment
Friendly Posted March 22, 2019 Author Share Posted March 22, 2019 I just realized I misunderstood the term PAR...it's a type of bulb, not a way to measure light. Quote Link to comment
Horerczy Posted March 22, 2019 Share Posted March 22, 2019 Its both actually. For lamp type its Parabolic Aluminized Reflector. But it also means Photosynthetically Active Radiation. Currently the best metric for intensity of a light source for our needs. 1 1 Quote Link to comment
Friendly Posted March 22, 2019 Author Share Posted March 22, 2019 do PAR ratings directly corelate to wattage? Quote Link to comment
Horerczy Posted March 23, 2019 Share Posted March 23, 2019 Higher wattage fixtures do tend to have a higher par output than lower wattage fixtures of similar design. However higher efficiency leds can have drastically different outputs with the same wattage as cheaper made leds. 1 Quote Link to comment
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