My interpretation of the waterflow pump is a powerhead with a venturi to supply the tank with additional water flow and also aeration. It is a good idea to have lots of circulation in a planted tank to ensure that the CO2 and nutrients get to all parts of the tank. Of course, not so much water current that it uproots all the plants!

Aeration, however, is not needed during photosynthesis when you want the CO2 level to be high and the vigorous aeration provided by the powerhead will only cause the CO2 to be dissipated into the atmosphere. However, during lights out, it is a good idea to have some aeration to aid the growth of beneficial bacteria and also to ensure that the oxygen levels don't drop to dangerous levels. This is especially important if you have a tank well stocked with fishes.

In conclusion, I would add the powerhead if you don't have sufficient water circulation and only activate the venturi at night when lights are off.