How to choose a pump station?
The suction pipe is the most responsible for the system portion of the surface pumps. Error diameter of the pipe and mounted on this most critical portion of the pump works.
As the suction pipe I recommend use of plastic tubes or collapsible flexible reinforced hoses. When installation, try to minimize the number of abrupt reductions, extensions, as well as pipe bends.
Calculation of pressure losses in the suction line can be made here (calculator).
For the calculation we need the pipeline section, the vertical height and length of the pipeline horizontally.
This result should be compared with the index of vertical suction pressure surface pump. Usually this 7th., 8th., 9 meters (Akvatehnika, JEELEX, AQUARIO, WILO, respectively). So, if your final figure is more than the pressure of the suction pump, the pump will not work.
Just try to change the tube diameter.
IMPORTANT! When assembling suction line must provide a continuous slope from the pump to the pipe supply intake is not less than 1 degree, to avoid accumulation of air bubbles and the formation of air pockets.