Help brownish/green algae not going away

[Debbie V]

In my 5 gallon tank I have 1 mail veil tail betta and 4 golden pristella tetra's. I have never had issues with this tank in 4 mo's. Now just about a mth ago I noticed a greenish/brown algae growing on the blue/white stone and some on the walls of the acrylic tank. I do monthly water changes-about 25% each time. Also use water softner. A wk ago I removed 25% of water and (as directed) removed the carbon filter for 6 hrs after adding Tetra algae control. I then added new water back with water softner. Here I am a wk later and there is algae forming on the stone again and in a couple of spots on the inside of tank. I usually have a very clean looking tank. Suggestions?

 

[ocean]

In that small of tank you need to do weekly water changes at least. And the tank is to small for tetra's.

 

[Debbie V]

I have done monthly changes for 4mo and the tank has been great. The tetras and betta also seem content. Just curious as to why after 4mo's the tank is developing the algae. I fear a weekly change for so few fish could cause more of a ph imbalance. Maybe I'll try bi weekly and see how it goes.