This is frustrating too..... Pic attached.With so many different & often conflicting viewpoints it does get confusing to flush out fact & fiction. Often both are true for the systems in operation, which brings me to, “what do you want for a reef tank”.
For the first ten years in this hobby I vacillated between experiments. Working overseas on a 28 day on/off schedule pushed me into thinking long term. It all came together after reading John Tullock’s book, The Natural Reef Aquarium. His main theme was inhabitants compatiable in a captive reef tank and
“Less Technology / More Biology.
You should set up a small display tank with the critters in the sandbed. I did a 10G tank with no fish. Only sandbed critters and decorative macro with ghost shrimp. As I drank my first cup of coffee, I feed the tank. It was enjoyable to watch pods grab flakes bigger then they were. When ghost shrimp would eat red or green flakes, you could see the colors of the food as it entered the intestines. Later, I added mollies which reproduced live fry. The pods were bigger than the baby mollies.