Particularly troublesome pieces (no hair algae on other scleronephthya rocks):
Bristle worms out of control:
or aiptasia, regrowing back every 3 weeks:
Treatment of such amount of aiptasia leads to the shaking tank balance and coraline dieoff, not good. There are fish and
crustaceans, that can control bristle worms and aiptasia, but no Christmas tree worms in such tanks (and I have them).
Add skimmer, that is not keeping water clean and energy efficient powerheads, giving the soft flow, but losing the bearings all the time and starting to rattle... Not a nice life for a reefkeeper, especially knowing, that this is an own doing
Seeing other people's tanks photos: crystal clear water, not a sign of troubles you are facing. Trying to do the same, what they do and discover, that there will be some obstacles, preventing this... Pretty frustrating. Wanting to reduce all of this to manageable size, but already having too much inhabitants and having headache over this.
Back to business: choices to regret.
In my humble experience, one sun coral (hardiest of all of them) with few heads is less troublesome, than several big colonies, that require 8 cubes of frozen food at each feeding (twice a week, more frequently in smaller doses is desirable). At first, this amount of ready made food is more expensive, than grated raw seafood, that pollutes water more. But both will pollute water.
And then there are tanks with even more sun corals without these problems:
link,
link,
link,
link.
Here is how and what I'm feeding to my sun corals collection.
Sorry, have to go.
This is how the gorgonians, dendros and scleros tank looks like (no many suns),
one more,
more, and the
main article on topic.