Sorry jmhart---posting at the same time and didn't see your comment about PAR. Thanks for the links---I'll check them out!
lighting theory - very long post!
- Thread starter cellodaisy
- Start date
Jpappy is right, lumens are not an accurate measurement. Lumens does not reflect how much energy is available for the plants, because as lumens are measured, they apply to how the human eye senses and uses light.
PAR is what you are looking for, not lumens.
PAR is what you are looking for, not lumens.
... and I'm sure different plants have different needs. Any "rule" would be approximate, I just can't help thinking that there has to be something more accurate than WPG.
Rex Grigg's LIS theory is complete garbage. If you check his math or try to follow his logic/calculation methods you will get results no where close what he says. I think us hobbyists need to band together and re-educate him. He seems to be confusing Lux and Lumens.
While most of can agree watts aren't that great for creating rules with, even creating a rule with lumens has some problems too. And with any rule, reflectors are rarely taken into consideration. A compact fluorescent bulb of 23 watts may put out 1600 lumens, but with the considerable restrike and lack of suitable reflectors, way less is getting into the tank/to the plants.
To refine your theory I would channel it in the direction of Rex Grigg, but do it correctly. Your lumens/watt idea is kind of the same as the old rule, just a little refined. Check out this page for a different approach(shown to me by MG):
http://woo.gotdns.com/Aquarium/Lighting.htm
It talks about lumens per square inch of surface area. I consider it to be slightly better than the WPG rule, but definitly not the end-all-best-rule-of-awesome.
Any rule developed for bulb/power output should be independent of reflectors. Reflectors are different across the board, and require their own separate review. Using a guideline, like wpg, should be used in conjunction with the best reflectors possible.
Yes, I did try (and, of course, fail) to follow Rex's mathematics and his use of the terms lux and lumen, but it got me started it this direction so I needed to give credit where it's due.
I also mentioned that reflectors will affect lumens/watt. Perhaps I should have been more clear, but I meant to communicated that the manufacturer's stated lumens/watt will be higher than your actual real-life lumens/watt, especially since we are only counting the light that stays in the tank.
I believe there are two significant differences between what I outlined and the old rule. (1) It takes into account the different efficiencies of different bulbs and (2) it uses surface area instead of volume, though I'm not sure of the value of that and am just taking Rex's word for it.
This appears to be exactly the same method I outlined. Am I missing something?
Thanks for your feedback!
LOL i read over your theory too quickly. As soon as I saw "Rex Grigg" I got thrown into a rage. I really absolutely despise that web page. So many people consider it the coolest thing since sliced bread.....and it doesnt even work. Sorry for my behavior.
But yes, now that I actually read your entire post I give you 2 thumbs up:thm::thm:. Now to work on something involving PAR LOL.
But yes, now that I actually read your entire post I give you 2 thumbs up:thm::thm:. Now to work on something involving PAR LOL.
