Husbandry is very basic at this point, frag tanks are bare bottom so they get detritus siphoned out every 2 days which takes just a couple minutes, I've hook the holds a filter sock over the sump so I just hang the siphon tube on it and the 4 tanks get done quickly.
I have to keep the flow pumps clean 2-RW-4s in 2 frag tanks and 2- WP25s in the other tanks, the 2-QT tanks presently each have just 1-WP25. Depending the how high the water level determines WP vs RW. The power heads get an acid bath about every 2-3 months. That's about it besides scraping the glass for the frag tanks.
My display has sand so I'll stir the sand since I'll get dark areas that will show. I'd say I do maybe a 50 gallon water change (on 650 total gallon system) about every 6-8 weeks. I vacuum the sand so have minimal if any areas of sand that get to an anaerobic state for bacteria. I siphon the sand out in sections over the course of time using the vacuum so I'm replacing it with new sand. If the sand vacuum doesn't pull enough out I will literally stick just the tube in and siphon just sand.
Basically I don't have 'old' sand in my tank more than 4 months, it's being stirred and or replaced.
My old 400 I didn't do this which I don't know had any impact on healthiness of the corals but I like the idea of less detritus build up over time. Steve Weast and others who've systems I admire incorporate the "rotation" or replacing the sand over time.
Nutrient control I give all the credit to a skimmer rated for 750 gallons and a neck cleaner, the "swabbie" I know is responsible for low levels, my PO4 last checked using my electronic UL reader was 0.00 and NO3 is 2.
I dose ME polyp extender which replaced Acropower, acros seem to like it better and I don't get any extra PO4 build up.
Sorry for the long write up that basically says I keep the pumps clean, the sand cleaning I don't think has anything to do with the happiness of the acro since on the old tank (I replaced the tank with the same footprint due to seam issues-i just replaced it before it leaked

) I didn't do that.
I've got a monster Ca Rx that keeps things rock solid stable which is critical
Sorry for the long write up with so little substance LOL