Hey Clive,
I just have a couple of questions regarding this part of your post. When you say that plants cannot compete against algae, do you mean that in a general sense or specifically in regard to competing for nutrients? The reason that I ask is that the common advice I read from experienced aquarists is that the best defense against algae is a large biomass of healthy plants, and that healthy plants are very algae resistant. This would indicate that plants are competing against algae; whether it's competing for nutrients, light or just for physical space. What are your thoughts on this?
Cheers
Hi Libba,
As it turns out, in just about every sense of the term, plants cannot compete with algae,
especially when it comes to nutrients. Yes, I know, a lot of experienced hobbyists say that plants compete with algae on almost every website, but it's not because they understand the facts, it's because The Matrix told them what to think, and they then thought it. In other words, they read it somewhere from some source that failed to do any kind of research and simply hypothesized what was thought
should be. In fact, many myths that proliferate today have nothing to do with science but instead have been handed down one source to another. Think about the popular myth that nutrients cause algae. how many websites and experienced hobbyists continue to purport this?
It should be obvious that algae are microscopic in size and mass and therefore their nutrient uptake can only be microscopic in volume and mass. When you have an algal bloom in the tank it seems as if the algae are everywhere, right? But if you were to scrape off every cell from every surface in the tank you'd see that the entire amount would be very small compared to the mass of the plants.
Plants have nutrient reserves, so they can survive a blackout for some days. Algae do not have vast reserves of nutrition. They depend on the light to produce their food. That's why blackouts work in eradicating some species from the tank. That's why algae is so pervasive, because everyone thinks that more light is better and that it will enable plants to outcompete algae.
Algal spores are everywhere in the tank and they even inhabit the biofilm covering the plant leaves. When the plant is in poor health their tissues begin to decay and they actually start to leach their internal chemistry into the water column, including nutrients. In a way, it's a sort of bleeding. Algal spores are right there at the site of the wound and can actually feed from the leeched products. They don't even have to compete because they are like vampires feeding from their victim.
In our tanks the relationship between algae and plants are that algae are the predators and plants are the prey, so yes, a healthy plant can resist their attacks, but prey do not compete for resources with the predators.
Cheers,