Water change issues for reef aquariums

How often do you need to do water changes in reef aquariums!
If you use carbon and refresh properly, if you use gfo and refresh properly and if you use algae externally properly, clean prefilters each day to two days, then no! then rare water changes are cool.
But if you do not use these, then be careful and do 1 third to a half max each time each two weeks as a water change. When you do a water change, the guys in your water are removed that do the work before your cyclers, too many out at once and PH may collapse and more!
That's the thing, which reefers do it exactly right? or have build in fail safes to keep PH always stable even with water changes!!

How the new water may affect your reef tank pets.
The deference in temp in container to tank water, PH semi shits its self, for a moment or two and thats all it needs, if left in container for a few hours, co2 and it shits it self for amount or two once added  to your tank water and so on and so on. I got my info over a very long time with the help of professionals in marine science and my own studies along with the help a pharmacist friend way back who did our specialised testing for us on not just varied chemicals and reactions but micro organism and not just ich and oodinium. oh and not that he did this for us but a pro at this can test chems for our hobby and make the out comes available to said friends and they can copy those chems, not that any one would do that! Here is a few links that help a bit, I hope! The gill area mucus PH and their ion pumps are what needs to be protected and what occurs due to fishes massive amount of drinking they do from surrounding water they swim in, they are where its all at!
Gills
http://www.fao.org/docrep/009/t1623e/T1623E03.htm

https://www.fondriest.com/environmental-measurements/parameters/water-quality/ph/

http://www.fishtanksandponds.co.uk/aquarium-science/gills.html

https://www.sciencedirect.com/science/article/pii/0034568778900920

what affects PH
https://endlead.weebly.com/factors-that-affect-ph.html

http://www.reefkeeping.com/issues/2004-09/rhf/

https://www.ratemyfishtank.com/blog/what-you-need-to-know-about-ph-in-marine-aquariums

https://www.reef2reef.com/threads/factors-that-control-ph.311299/