righty

-- Wrap the modem and monitor
local mon = peripheral.wrap("top")
local wmod = peripheral.wrap("back")

-- Open different channels for different liquids
wmod.open(3) --For water tank
wmod.open(4) --For lava tank

mon.clear()
mon.setCursorPos(1,1)
mon.write("Liquid status:")

-- Main loop, never stop
while true do

  -- Check for incoming data on any open channel
  local event, modemSide, senderChannel, replyChannel, message, senderDistance = os.pullEvent("modem_message")

  -- Add one case for every liquid
  -- Change channel and text for each

  if senderChannel == 3 then
    mon.setCursorPos(1,2)
    mon.write(message .."        ")
    print(message .." from Water tank,")
  elseif senderChannel == 4 then
    mon.setCursorPos(1,3)
    mon.write(message .."        ")
    print(message .." from Lava tank.")
  end

end