This is the father of the Eheim 2260. Lots of simularity. 2260 has a 4.8 Gallon filtration volume. I would says its an early model of the 2260
To find out its filtration volume, measure the depth of the filtration area only and the internal diameter of the canister.
Volume = (Diameter / 2) * Radius squared * 3.14 * Filtration Depth
11" diameter canister with a 14" filtration depth
Example, 11/2 = 5.5 * 5.5 = 30.25 * 3.14 = 95 sq/in * 14 = 1330 cubic inches = 21 Liters of filtration volume or 5.75 Gallons.
I would like to know the filtration volume to see if its the same as the 2260.
You can find calculators and conversions here
http://www.innovationlandscaping.com/fx5/forum/viewtopic.php?f=32&t=38
Exactly. In order to run both pumps on the output you would need to modify the output and input diameters to accomodate that much flow.
OP, you could probubly upgrade the pump with a 2262 pump because the 2260 can be adapted with the 2262 pump and get a 900 GPH flow rate at zero head with all the same pipe diameters.