Thats the key, never give up, never empty the tank and again, never give up.

My tank now is loaded with a weird macro algae that I have never seen before. It could have come from the Sound behind my house or entered the tank through osmosis. I don't know but it is growing on everything. Not as bad as the invasive sponge I had a couple of years ago, but almiost.
It's nice looking and doesn't cover the corals like the sponge did but it does get long, about an inch and shades corals.
Due to my wife's health, I don't have the time to work on my tank much but I do occasionally get in there and pull it out in clumps. The last time I removed a pound of the stuff. Hopefully it is a cycle and will abate on it's own. I don't know but these little things don't bother me. At 55 years old I consider the tank a success and everything that happens I feel are just an interesting and learning part of the hobby. (I am much older than that)
The worst thing that could happen is it crashes and I dump it out and use the tank for turtles.
Of course, these large seaweeds I collected.

In this next picture you can see that short, green invasive stuff.