Lighting

I have 2 250 watt IceCap ballasts. One has a 14k hamilton and the other has a 12K Reeflux. By the way, both bulbs are almost identical to the eye.
I noticed that once in a blue moon my hamilton bulb would flicker (when I say flicker I mean a very fast and subtle flicker, one can only notice when paying close attention) but this would occur for about a minute and disappear for a long while. It actually doesn't happen anymore. On the Reefluc bulb, however, this flicker does not stop.
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