- it has nothing to do with light, since having real vs. similar fake plants does not affect light levels.
agree, and I have done experiment with this. i only cover half top of the tank with duck weed. but the rest of the tank is algae minimal. so its not that the duckweed is blocking light.
- it has nothing to do with taking up the space, since even in highly planted tank, the volume of plants is maybe max. 5% of the aquarium. And if that would be the case, just putting more rocks to the aquarium would do the same thing.
- it has nothing to do with healthy plants sucking all nutrients before algae gets them, since people are doing fine with EI. And EI by definition has EXCESSIVE amounts of all nutrients. And algae needs very little nutrients anyway.
agree. but remember, EI only dose N, P, K, and micro.
- it has nothing to do with CO2, since CO2 levels are adjusted based on desired ppm concentration and in high tech tank there is plenty of CO2 for algae that needs very little of it anyway. And if algae would simply suffer from high CO2 levels, CO2 would be used in non planted tanks to prevent algae.
CO2 only come into effect that it helps plants grow
So what difference do the plants do for algae? Since if in theory one adjusts ferts & light to maintain same exact water and light parameters and replaces the plants with fake plants, almost every aquarium keeper would place their money for the aquarium turning into an algae disaster.
Edit: The only somehow logical answer to this equation I could think (without allelopathy) is that algae uses ammonia and plants help keeping ammonia levels down.
its not ammonia, because commercial fertilizer has ammonia in it.
i think it's not Macro and micro nutrient either that plants competing, but organic compound that is not specificly mentioned. And this organic acts similar like a catalyst. it is being consumed (while catalyst is not consumed) by algae. when this organic present, it makes algae thrive.
i have hight tech but low growth tank with EI dosing, it has no algae at all. why? because I don't keep fish in that tank. no fish = no organic waste = no organic nutrient.
also, Amano suggest that for the first 3 months, to put activated carbon in the filter. why? to absorb organic material.
allelopathy is real, but not all plants do it. for general discussion, i say it's more about nutrient competition. but the nutrient is not macros and micros, but organic.