I do daily water changes which add up to 20% weekly on my main display with an auto water changer. I only go in and make new saltwater once a week and mix it in a station I set up. I drain all the waste water at the same time which I will also soon automate. Everything else is just routine like cleaning the acrylic, bi-weekly carbon changes. As for water testing I really only test when setting up a new tank which I do without fish using ammonium chloride and Dr. Tim's [free plug] One and Only. Currently running 5 tanks with 2 down at the moment. Semi retired [work from home] 45 year hobbyist. No time for real work with a fish room.
In the process of changing as we speak. I had been using IO, but I am currently changing my 135 over to a reef, mostly LPS so I am switching to Tropic Marin for a minute and just picked up a few buckets to try. I used to use the Neo Marine years back when Stephen came out with his New Zeo system as well. Truth be told I walked away from salt 7 years ago due to a huge crash on my 300 when I was out of town for three days. I'm sure you've heard the stories over the years, but it took me 6 years to get over the loss.
The 135 is still fresh water, so I will be using this on the 300 FOWLR and I also have a 75 mini reef I call it just under way [two month cycle] where I will see how it does.
Lots of changes while I was away so not stuck on a brand just yet is the short answer.
My target is weekly 30 gal water changes (tank is 120 high) but in reality it is more like every 2-3 weeks. I scrape glass as needed and empty skimate from the reservoir when go downstairs where my filtration system is And I think of it. I have my RODI system plumbed directly to my ATO and 35 gallon norwesco tank that I mix salt in. Both are equiped with old school manual float valves to shut it off. I very rarely test the water. Only if there is a problem. Tank is well established and low maintenance.