I assume your tank is 135.4 gallons. Depending on your system felt filter socks are the most common choice over our plastic mesh filter socks. As far as size and number of filter socks required we can give you the best choice if we know if it saltwater, freshwater or reef and if it will be stocked with an average bio load. Typically, with a 135 gallon aquarium we will use 2 to 4 x 4 inch ring by 14 inch filter socks or 2 x 7 inch ring by 16 inch long filter socks.