Let me answer your other question on water changes, and I am going to say something a little controversial---or at least not in line with advised official practice: first, if you are having ghosty problems with a tank, definitely, a good series of water changes is the best I-can't-figure-what's-wrong cure.
BUT---we ran larger tanks in the 80's without many water changes, and it can be done if you are willing to accept some limits: first, have plenty of live rock and sand. Secondly, have a lot of plain hard discosoma (red, greenstripe, brown, purple) mushrooms and things like green star polyp, yellow star, etc, and brown buttons, leathers and things like kenya tree, things that can become outright pests in more modern tanks, because of their growth rate. These things are tough. Even fish that tend to bother corals leave these alone, so they will proliferate. They take less light than stony coral. And they're living filters that can filter the waste of messy fish. Keep your fish balance with 1) creatures that live in the sand and clean it: jawfish, watchman gobies, nassarius snails and conchs. This keeps your sand in very good order without the need to worry about it. Keep a lot of bristleworms and a variety of micro-hermits and small snails...the strombus grazers are brilliant at getting into tiny crevices in the rock. 2) quarantine every fish obsessively. Don't let the very first or very last fish get into that tank bringing ich to infest that sandbed. 3) have a big refugium with sand and rock as well as cheatomorpha algae. This will keep the microlife of your tank in good health. 4) don't run a phosphate reactor more than it takes just to be rid of hair algae, and unless you see hair or green film algae redevelop, don't run it. 5) test at least every week, and keep a log book so you can dose INTO trends, not after your water has gone wonky 6) you can eventually try some lowlevel stony corals like hammer and bubble, but if you do, you must supplement calcium. 7) watch your corals for any sign of unhappiness: if those mushrooms and buttons are extended and happy, your tank is happy. Test immediately if you see them otherwise. 8) run a water change a couple of times a year. You'll get cyano periodically: do NOT use a chemical treatment for it, just do the lights-out treatment.
It will work. It's not capable of handling fussier corals, or really delicate fish. But if you stick to the hardier fish and keep that logbook meticulously, you can manage it. You can also, at some point, either ramp up the water change situation to handle fussier creatures, or, at a low ebb in your time-available lifestyle, take it close to zero-care.
Everyone note this: a tank over 100 gallons has leeway that a little tank doesn't. The water changes are more important for a little tank than a big one, as long as you stick to hardy species---again, it's that big water volume and all that rock and sand; and a big one that decides to let critters handle the cleaning and that is happy with less than the bleeding edge of fancy reefs and exotic fishes, --- yes, it can be done. Building a bulletproof tank with minimal changes takes realizing that what's new and shiny at the lfs could be a real bad idea in your tank; and it takes doing some careful research about what you put in there...(I made a real bad one: a ghost eel, let loose in my bulletproof reef without proper research: it ate 300.oo worth of fish I really liked and I had to unbuild my reef and disturb all my corals to get him out. This is what can happen if you're stu-pit, like I was!)
So understand---you'll be giving up access to some types of fish and corals, but you'll have a real pretty tank. I kept mostly damsels, because I like them and they're colorful and move beautifully in a big tank, but most commonly kept fishes are ok there, even some with reps as coral eaters. The soft corals are not real appetizing.
Keeps my water crystal clear
