What kind of tubing do you use for the mini water pump? Based on a user comment, I bought 1/4" ID vinyl tubing--which works on the intake. But the outflow only has a small rubber nub which will fit, but not hold the 1/4" tubing. It appears that 1/8" OD tubing will fit inside the rubber--but where can I buy something that small w/o having to buy 500' online?