As the owner of a deep quarter round, glass, (though not THAT deep) I can say that getting a superstrong Mag float with scraper attachment (suitable for acrylic) is sanity-saving. That's the biggest problem with these super-deep, beyond the reach of a human arm, type tanks. Placing a few powerheads IN the rockwork might be a good idea, as well, and employing a cuc involving some serious sand-sifting would also help.
