Computercraft CTank Controller

-- quick program to control a crystal tank
max = 946000 * 1000
rsdir = "left"
ontime = 180
offtime = 60

t = peripheral.find("cccrystaltankauxtile")

while (true) do
  level = t.getTankInfo()[1].contents.amount

  if level/max < 0.9 then
    redstone.setOutput(rsdir,true)
    sleep(ontime)
    redstone.setOutput(rsdir,false)
  end

  sleep(offtime) -- leave some off time for other processing
end