Anyway the WPG is just a lighting for dummies rule...
You calling me a dummy, Kenneth_kpe?

Why don't we take this outside?
Ok, now you have me curious, gf. I read the article and understand it's principles, very interesting. Now, I'm going to ask a stupid question. How do you calculate your lux rating on your bulbs? I'm probably missing something really obvious, but I now want to know the lighting of my tank based on the article you posted.
Your simple rule, gf, is effective too. My glosso doesn't carpet in my 10g, it grows upwards. The jury's still out on my 15g, the glosso doesn't grow upwards, but I just added it a week ago. The glosso there, however, looks more compact and bushy.
Sorry, to hijack the original post with my question, Spiceweasel, I mean no offense, but I always like to learn something new.