Agree...and well said.Low tech is still a thriving thing. But even at low tech, aquarists still test their tanks for a lot of elements. Just knowing what's in the water column is a huge leap forward. Whether the hobbyist wants to take action is completely up to them.
I think the advances have allowed reefers to push the challenges of harder, even impossible to keep corals and fish in a closed system. Just a couple decades ago (so I've heard from seasoned hobbyist) breeding fish in captivity was a huge thing. Now it's happening more often with a variety of species.
You could be successful with the diy system you made, there are a LOT of reefers who just add prime to tap water. Then there's some who just go tap water straight up. But not knowing what's in the water to begin with is was a lot of people debate about.
You can use non ro water, but there are chances your taking when doing so.
Thank you.