Nitrate (NO3) and phosphate (PO4) don’t cause algae. Ammonia does!!

There is this myth, that nitrate (NO3) and phosphate (PO4) cause algae which is spread like a wildfire. But that’s not true at all! In this article, we will try to explain why NO3 and PO4 aren’t responsible for algae bloom in our freshwater aquariums.

Firstly, you have to realize, that algae lives in two stages. First stage is an algae spore and second one is common algae, how you know it from your aquarium. You can compare it to a butterfly. First, there is a caterpillar and after a while beautiful butterfly.

But here is the fundamental difference: Each stage eat something else. Caterpillar eats lettuce or whatever but butterfly not. In algae case it is the same. Algae spores eat ammonia (NH4) and algae eats nitrate (NO3) and phosphate (PO4).



Algae spores are invisible and they are present in each aquarium. We have to prevent them to become an algae. How we said before, they need for their growth ammonia (NH4) and energy – light. You can’t give them these two things, otherwise there will be a big algae bloom. You can’t turn off lights because plants wouldn’t grow so there is only one possible solution: There can’t be any ammonia (NH4) at all!

Ammonia comes from old, unsightly leaves, waste of fish and from feed. We have to keep level of ammonia as low as it’s possible. How? We should instal big filters, where is ammonia transfered to nitrate (NO3). Algae spores aren’t able to recieve nitrate, so doesn’t matter if nitrate (NO3) levels are high. We could also change water regularly to cut ammonia levels down. But what is the most important? We have to keep plants in a good shape, because when plants are weak -> system is weak -> ammonia is present and algae spores become an algae. So if you don’t want to have an algae bloom in your tank, you have to care about your plants and you have to keep aquarium clean.

How we said before, algae spores want ammonia (NH4) and algae needs nitrate (NO3). You are reading this article probably late, because your algae spores became regular algae. But don’t worry. You can still fix it. You have to start adding nitrate (NO3), phosphate (PO4) and all other important nutrients including CO2. It doesn’t make any sense? No, it makes sense. You have to care about your plants, because they aren’t in a good shape right now. Old leaves produce ammonia (NH4) and algae spores become an algae. Fertilizing will cause that your plants will be in a good shape and they won’t produce more ammonia (NH4) so there wont’t be a new algae. Additionaly, healthy plants will eats ammonia so algae spores will suffer. On the other hand, algae which is present in aquarium right now will be grow because it is full-grown algae which eats nitrate (NO3). Yeah, that’s true, but you will remove it after a while and there won’t become another one, because you removed ammonia, so no other spores will become an algae. Pretty cool, isn’t it?

If there is an algae bloom in your tank, and you will cut the dosage of fertilizer down, it is the worst you can do because your plants will suffer from lack of nutrients, their leaves will be unsightly and will cause ammonia (NH4) -> algae. Plants have to be healthy, only in that case algae won’t be present in your tank!