you're already going down a slippery slope called reefing.... embrace the dark side and just get a chiller...
but jokes aside... I've got one of those mini chillers that somebody gave me but I've never used...
like this one ... http://eastoceanaquatic.blogspot.sg/2014/10/al-mini-chiller-review.html
can pass it to you to try out, not sure how effective it is