Definitely more coral then! LOTS more coral! Toadstools can be funny, but are usually bulletproof. I run carbon baggies in my filtration to help with their toxins. Perhaps could use a third light over your 48" tank.
I've had bad luck with chaeto, so I'll let others chime in with advice for your Tidal filter. However, I've had amazing luck with display macroalgae, sometimes too much luck. Pom Pom Gracilaria would be a good addition to your tank to compete with GHA, as would Codium. Both excellent growers (Codium, I understand, may be dependent on where it is harvested--I've gotten mine from ReefCleaners and it grows well in my tanks). Pom pom for me grows so fast (and actually look great) that if I don't trim it every couple of weeks it tanks my nutrients.
Some other softies might also help dial in the nutrients. I like waving hand Anthelias. Not as invasive as Xenia and looks great. Sinularia does well. And in my opinion, picking a soft coral to cover the back wall of your tank like GSP or a fast-growing paly works almost like an algae scrubber. My back wall is covered in green palys--maybe not advisable due to the amount of palytoxin these guys might produce--and I'm sure they are sucking up nutrients like crazy:
Please disregard all the aiptasia back there. I can't reach it