Hi, I a have a 25l tank with 7 fish in (guppies and neon tetras) which is quite a lot I know but I’ve noticed that brown algae has started to appear on the gravel, ornaments and glass. It’s not a lot but I know how fast it can spread so I’m thinking of using phosguard has anyone ever used this or any cheap alternative? I do 25% water changes weekly and have my light on 10 hours per day. I have anacharis, Java fern and Marimo moss balls in and just standard white gravel.