Although the article did not reveal anything new to me, I am suprised the author could only think of 30 causes. Indicating the many causes, which is not all of them, truely points out why it is so tough to naturally control the stuff. Yeah, Pond Trade magazine provides some interesting articles and products even though I do not always completely agree with them.
Pea Green algae is really not that bad of an algae to have in the pond as long as your alkalinity and water circulation is good. It is mostly just a problem for folk for aesthetic reasons. I know aquaculture farms literally fertilize their ponds so to grow this pea green algae and other organisms so to act as a bio-filter.
The problem comes with the more invasive algaes. The more invasive algaes are "self fertilizing" plants, that act more like a parasite such as fungi or the parasitic vines that grow on trees. So, no matter how well you control the organics in the water, these particular algaes will always thrive since all they need is the smallest amount of micro-nutrients. Most algaes require macro-nutrients. All it takes is a matter of time for the proper species to be introduced by spores, through birds or plants or whatever, for it to get started. These more invasive algaes are the algaes that can lead to complete aquatic kills. These algaes are why chemicals are to be properly implemented. If not wanting to use chemicals, then there is a very increased reliance on plants and other bio-filtration to try to significantly reduce those micro-nutrients and to encourage other algaes to grow that emit their own chemicals to compete with the more invasive alges.
Controlling algae is like controlling dandelions or wild grasses in a pristine bluegrass lawn. I have not yet seen a single organic approach that is the easy, quick "fix all" to the problem without using chemicals.
Also, which seems to occur more often with these articles and forums, there are too many "big fish" stories by folk that say they have found the easy, quick "fix all". Algae seems to be like the running joke and contest between folk that can tell the most unbelievable stories as to why and how their ponds "never" have algae problems. When their solution does not work for someone else, then they use the easily accessible back door of, "everyone's pond is different", so to revoke them self of responsibility for giving advice that failed, that is to put it quite blunt. I like the organic approach and, as a farmer, agree to the theories, but it all depends on what you have to work with.