So I am collecting parts for my splitter and a fellow on ebay is selling hydraulic tanks. I have a 22 gpm 2 stage pump and was wondering if a 20 gallon tank is enough or I will have to go up to 30. He sold his last 25 gallon and won't have anymore until this summer. I seen 20 gallon tanks advertised having 16 usuable gallons and thats what got me thinking if I need a 20 or 25 gallon. I noticed timberwolfs tw-5 has a 22 gpm pump and only has a 15 gallon tank. Any suggestions?