Anachris and BGA

That's really interesting! It talks about allelopathy in the book 'Encyclopedia of Aquarium Plants' by Peter Hiscock. Here's a bit of what he says:
"Allelopathy describes the production of chemicals by an organism that adversely affect another organism and/or advantageously affect itself. In the case of plants, these chemicals (called allelochemicals) are often readily produced to inhibit the growth of other plants or algae, or to prevent animals from eating the plant. [...]in the enclosed environmnet of the aquarium, allelochemicals can quickly build up, with various effects on some plants species [...]The allelochemicals produced by some aquatic plants have a particularly adverse effect on floating plant species and algae. This is one of the main reasons why a well-planted aquarium may not show signs of algae blooms, despite hight nutrient levels and strong lighting"
So if the allelochemicals can affect animals as well as other plants, I can see a photosynthetic bacteria being effected - it falls right in between the two! Sounds like the theory could be right, especially with what you've seen happening in your tanks. I love to experiment - I'd be inclined to put some Anachris in the tank and see what happens...

I look forward to reading the results!
I sure wish I'd loved learning this much when I was in high school...

Let's talk reality:

Allelopathy has not been shown to exist in any natural aquatic system.
Anachrais(Egeria Densa is a plant I know very very well, it's a nasty weed here and I do control for the state.

It does not do anything as near as anyone can tell in practical planted tanks.

Now if you grind some Egeria up and put it on BGA(which species of BGA BTW? That is a very key piece of info. We don't know since they did not give a reference or did he? Or Diana Walstad?) That is not very realitistic in terms of what actually happens with live material.

Lots of things can be ground up and oput on things to inhibit growth, but if you ut them together ina tank, no interaction will occur.

There is one genus and likely just one species that causes the problem.
So unless the study was on that genus, it really doesn't tell you anything worth while about BGA.

Issue no #2.
What are the odds that all 300 species of plants have ther same effect on algae and BGA's?

I clearly have not had this plants for many years yet have no BGA, so are all my plants doing this as well?

Allelopathy is nice to talk about and all..............but the reality is I've never seen any evidence to suggest it occurs in aquatic plant tanks or the research on the field.

Grinding something up and putting it on cultures(of non target BGA or other organisms) in little wells is not a supportive argument to make this claim.
Maybe it happens, maybe I'll cure cancer, but I doubt both equally.

On a more basic level, you can add the plant and see, when you fail at controlling BGA, you can do a blackout and start adding KNO3 from now on so you do not get BGA in the future.

Regards,
Tom Barr