I think it is the lights. Even the Marineland Doublebright LED light doesn't seem to meet the parameters of an actual Reef light. None of them do.
The Reef light (18") has 18W of consumption with very low quality LEDs. With a mere 1305 lumen of transmitted light, thats about 70 lum per watt. Cree are over 120-140 lum per watt consumption, so these 18 LEDs are equivalent to only about 3-4 Cree 3 Watt LEDs. Who, in their right mind would use 4 Cree 3 watt bulbs for a 18-24" tank?
The accepted standard for a 24" tank is 120W of CREE LEDs. This is about 10% of that.