I have a Rubbermaid trough. 20 something gallons and a float device so always full...
I won't have galvanized metal where my horses can stomp on or in it breaking it forget getting cut on a edge.
They rust and split seams as I see from my friends tank. We bought troughs at the same time, mine still is in great condition, galvanized one needing replaced this week at it is seeping.
My trough does
get algae in it but it also sits in the hot sun daily.
I clean my trough 2x a week regardless so makes no difference to me...algae or not, slimy or not, green or not...the brush is headed your way.
I was told by a friend to put a piece of real copper pipe, not big, a fitting will do and that will near stop the algae growth...lightly scuff the metal if it is new as a coating is on it, wash well then plop in the tank.
In my case, I'm going to suspend it on a fishing line so my horses not play or lose the fitting on me.
This is a new one for me, never heard it so no idea if it works or not...we shall find out.