Sometime it is a try and error thing. Try to remove the ehiem substrat, zeolite & those white stones in your next water change. This time just use sponge filter and wait for a few hour. If water become clear then you'll know the problem started from your media filter. I hope it help.

Also check your water source too. Unfiltered tap water do have sediment which may make the water to look cloudy & brownish under white fluorescent light.