Most growers make the low O2 DX after the root are sick, die, decay and the fungus presents. Then they go into the “crisis mode.” I have easy access to a DO meter anytime so that meter test results should provide a heads-up of any low oxygen problem at the onset, before the roots die and the fungi outbreak comes.
What DO concentration and DO Saturation indicated “low oxygen?”
I understand that most hobbyist do not have DO meters nor do they want a meter and actually have no logical way to test DO… most hobbyist totally rely on the DO Chart values and water temp and just wait watch and hope they won’t have low oxygen problems.