Hi Hoppy,Yes, you are remembering right. I spend several years trying to find ways to determine how much light we have and how much we should have. It is still a mostly a guesswork subject.
When I got back to this hobby about 25 years ago, after I retired, I did it largely because there was so much to learn, and so much that was unknown about the hobby. I have never regretted that decision.
Hi Hoppy,I think the biggest lack of information we now have is algae and why it grows or doesn't grow. Diana Walstad's book is, in my opinion, on the right track in saying that it is the nutrients in the water that are the key to having algae or not having it. Algae have no access to the nutrients in the substrate, except for what leaches out into the water. And, I'm intrigued by the idea that it could be iron in the water that is the magic key to algae problems. Unfortunately, it is also very hard to find a good experiment that could enforce that idea.
Hi Hoppy,Yes, I have seen those charts, but I haven't seen any data that would support a belief that certain wavelengths of light cause algae problems. That, too, is a very hard experiment to try.
Hi hoppycalif,My experiment isn't going to be a success. I suspect I don't have enough substrate in it, and the plants are not doing very well as a result. But, if I can't get both sides of the tank to start out doing well it isn't possible to see the effect of changing something on just one side. When I think about this some more I will probably start over again, but I need to keep the two betta's living while I do it. I'm still intrigued by what I read in Diana's book about iron.