I dunno. It depends... but if it really bothers you that much you can use flake food or any other kind of marine food. What really matters is that you get a good population of bacteria going. When you are done cycling you should have zero ammonia, zero nitrites and high nitrates.
Also I remember now why I didn't like the idea of feeding your chiller with the return pump. If you feed your chiller with the return pump and you put the output of the chiller into your sump you are creating a closed loop which will cause your chiller to turn off and on and not work properly. This is because it will chill the water from the return and then put it right back in the sump so the water in the sump will get colder and the temp regulator will sense it and turn it off even though the display tank is still too warm. The only way to bypass this is to use an external temperature controller and place the temp probe in the sump upstream of the output of the chiller.
I run my chiller independent of my reefkeeper lite because it acts as a redundancy in case the temp probe fails and the heater stays on.
