Yes, high plant density deters algae, especially because the plants use the nutrients that algae would need to grow, chemicals aside. I don't see how that provides any evidence for or against allelopathy...
Anyway, BGA is not algae... and I'm not looking for methods to rid my tanks of it, but actual experiences people have had with certain plants and BGA.
No, plants do not use up all the nutrients. We can easily add plenty of ferts for both the plants and the algae, algae are never limited in any planted tank.
Clear examples are found going back decades, simply google my tanks here or elsewhere on line. Videos etc.
If you cannot see why allelopathy is NOT present in aquariums, then you need to sit down and read more and think about the logic behind it. Then after that, what type of "control" might you use to test whether or not allelopathy exist in a planted tank in situ
If you add activated carbon to a planted tank, then this will remove the allelopathic chemicals. The hypothesis is that these chemicals retard/inhibit/ stop/prevent algae. So removing them should lead to algae.
However, activated carbon has been used for many decades in the hobby and has never found to induce any algae in planted tanks. the opposite in most case, cleans the tank up more and less algae.
So there's not 1, but 3 points against allelopathy.
1. Research does not support it.
2. Statistically improbable based on observations.
3. Experiments can be done and have been done that demonstrate it does not occur using real intact planted tanks.
Other than wishful thinking, what support can be offered for allelopathy?
If you wish to be specific, Oscillitoria is the genus that infest our aquariums. I identified this genus as the genus of interest for aquarist back in 1999.
It's not hard to get rid of frankly.
As far as plant species with and without it, that would be pretty much all plants, all 400+.
Like I said, the statistical evidence/hobbyists observations over many decades cannot support allelopathy
Do not say someone did not tell you.