There is a Holmes-Farley article where if I recall, there is not really a big difference between doing them all at once or over time. It’s like a 10% all at once is equal to a 12% over a day
I do about 1.5 gallons throughout the day with a heavier amount at night when I’m asleep. I use DOS pumps and they are workhorses but they are loud.
few tips: look at your dosing pumps. Some pumps, like the Ecotech Versa dosers, have a VERY NARROW tube. It will get clogged with sand, dust, molecules, quickly. I spent more time cleaning them than it would have taken to do the water changes. I had purchased the panel and 4 pumps just for water changes and they were a PITA.
No matter what, use prefilters on BOTH lines. BRS sells a 1/4” push to connect fine mesh filter that’s completely dark so algae won’t grow in it. You can also find them online as inline fuel filters I didn’t think I needed one on my fresh saltwater until a month ago when the pump head clogged (granted it clogged after a year).
I installed a T with ball valve before the dosing heads. I also purchased a cheap peristaltic pump (like 5gpm) from
Amazon and fitted it with push to connect fittings. Once every 6 months, I open the ball valve and hook the other end up to the pump. This flushes the lines (which are 60’ a piece).
