Taste test?
Well, I have ingested more than my fair share of detritus laden water attempting to start a siphon hose ...... after siphoning out detritus (which I do occasionally for aesthetic reasons) I used to wait for the particulates to settle and then test the clear water for nitrates/phosphates to see if the levels were higher than the remaining display water. They never were. It's crude, as I noted, with lots of ways to introduce error; but it's a least a data point(s) in discussions that always seem to lack actual data. Friend of mine recently entered the hobby and said his biggest surprise was the data-lacking, dogmatic opinions of many. He's an audiophile, so I pointed out that the same thing holds there too LOL