2) Measurement cup/beaker
4) Valve (some filter have this build in)
First of all, close the valve and disconect filter outflow from the tank. Turn on the filter while the valve still close. Press stopwatch start button and at the same time open the valve. Wait until 10 second and turn off the valve. Measure the water in the bucket. Multiply whatever liter you have in the bucket by 360 and you get l/h. It may not be the most accurate measurement method, but it close enough for our purpose.
I did tested with my Eheim 2217 without media and I got 3L/10 second. Multiply by 360, I got 1080L/h. It is prety close to the spec 1000L/h