ok so my 20 gallon tall has 13 fish in it. I have a fluval c3 with five different types of filters. It’s a planted tank with a bubbler going. I bought the master test kit and all the perimeters are in good shape. I had red algae a few months ago and no water change could get rid of it. I took out the old gravel and bought the eco one for plants that’s supposed to be one of the best for a planted tank. The red algae isn’t nearly as bad now it’s just small spots and way less frequently popping up. All in all changing the gravel to a natural plant substrate has helped tremendously. What else can I do to get the red algae to go away now that pops up? Again it’s much less algae and way less frequent so changing everything helped. Thank you!