i have a 135 gallon tank that has been up and running for over 5 years now.... i have been using a CPR overflow box.... i am getting tired of relying on a aqualifter pump to keep the syphin going... my tank is not drilled and i perfer not to drill it because that would involve draining it to drill it....does anyone have any ideas of a new overflow???? i have heard of one that is gravity fed with a airline check valve in the elbow to get the syphin started....any thoughts ????? please help me out

