Flow in 550 gallon tank

[scuba711]

Hello everyone. I have had my tank on the second level of my home, built in between two rooms, for about 6 years. When I set the tank up I did not do the required planning for water changes, equipment storage and maintenance. I have now started the process of moving it into my basement living area so I can complete it the way I really want to and to allow for better maintenance and fish keeping. I also want to start adding more corals. The tank is acrylic and 92"wide, 46"deep, and 30" tall. It will be backed up to my garage were I have built a room with two 200 gallon holding tanks that are about 8'x2'x2'. One will be a dedicated refugium with lots of rock and plants. The other one will be part of the system but will be separated out to do water changes. So the system will be close to 1000 gallons and I can do 200 gallon water changes. The lights will start as three 250 watt MH and T5 actinics as needed. I am planning not to run a Skimmer but have a large Becket skimmer if I see the need. I also have a large calcium reactor which I can use if I need to. I am not planning to have hard corals or high demand corals, just mushrooms and easy soft corals to add movement and depth. The main tank will have 300-400 lbs of very live rock with about 2" of sand. The fish I currently will all stay and includes a mixture of friendly triggers, tangs, rabbits, snowflake, dwarf angles, damsels, and wrasses. So to the question, what should I shoot for on my closed loop pump? Through the sump I will have about 800 gph. Doing a basic search people say 20-50 times the water volume...well I'm not planning on 20,000 gph. So I'm thinking the calculators I'm seeing are for much smaller systems. What are others running with similar sized tanks and inhabitants? Thanks a bunch