My specialty is preventing one key unlisted crash-the willing takedown due to loss from an unbeatable invasion. The give up crash I can't win crash.
Million bucks worth of animals and rocks overgrown with anchored invaders, unanchored ones (dinos) --it's the worst waste in our hobby and we are doing it ourselves by copying hardfast rules given from prior reef generations likely to cause these invasions.
Deconstructing five thousand lost tanks who wouldn't veer from convention:
-no more giant rocks stacks. Not that they're bad, I prefer the nineties wall look, but it's inaccessible. That gives you a reason you can't access down low, directly, to kill a target. So it spreads. You'll be reduced to working solely through the water, test and wait, react dose, try not to bleach this etc. external vs internal locus of control reefing is the most important choice in design you'll ever make. Those fed up with losing tanks go full on internal locus of control and take responsibility for their loss invasion before it happens. They know it will happen if they use the other way, they refuse the next loss and design accordingly. Nano reefers are allowed to stack rocks to the sky and back since a take apart cleaning is still easy. Large tankers need very little motivation to claim a given access job is too big, we will just let it ride. Every invasion wants this mindset from the tank owner, an allowance mindset, a reason to let the invader stay a while.
decide your stance on sand. Doesn't matter either way. If you choose sand, have the training and more importantly the will to clean it correctly so that it doesn't fill up with invaders or invader feed
Decide when you get your first virulent or potentially virulent invader if you are going to kill it by direct access, outside the tank, that way your water params are always set for fat corals and you're still invader free anyway, or decide if you are going to follow current rules of accepted uglies phase where we wreck tanks on purpose only for forty percent of them to wind up an algae challenge thread one day and then the loss mentioned above.
You can opt into losing your reef to an invasion right now or you can middle fence it, see what happens, and start an ID and water param thread as that first invader spreads just like every invasion challenge thread ever made.
We need to stop seeing reef tanks as things we set up and let spiral into oblivion, learn reef tank surgery and you'll create a reef tank with no biological lifespan. Be deep in that reef at times gardening and guiding, not lording over it at the top only, jacking with water params only and changing stasis away from what corals want and into invader suppression, which is external locus of control reefing.
Enjoy your old tank syndrome proof reef

B
*the strangest aspect of reef tank invasion isn't the actual invaders, it's the owners who don't like algae but actually hold onto it at all costs, purposefully wrecking their tank before their eyes. It's probably the most fascinating psychology reefing has to offer...the full on willing to self destruct no matter what attitude. You are only in the click if you risk your whole tank right off the bat with a full on sustained invasion, those who never ever ever ever ever ever ever permit algae are the outcasts - I love it this way. Never ending free online work jobs to log fixing external locus of control reefs.