Power sprayertanks are usually plumbed to feed the pump from the top or the bottom of the tank.
Top Pickup – This uses a pick up tube from the top of the tank to the bottom of the tank. The advantage of top pickup is that you don’t have to worry about a fitting leaking because the fitting is at the top of the tank.
We have not found tank fitting leaks to be a major problem. On the rare occasions when a tank fitting leaks, it is a slow leak that can be repaired after the tank is emptied.
The disadvantage of top pickup is that the pump has to work harder to prime. The pump must lift the liquid up the pickup tube then over to the pump. In extreme temperatures, this sometimes can cause vapor lock. This is particularly true when the pump has some age or wear. Pickup tubes are usually made of PVC pipe and so often crack, chip, or degrade over time, or get clogged with debris, impacting pump performance.
Bottom Pickup – This eliminates the problem of power spray rig vapor lock because the pump does not have to work to pull liquid up the pickup tube. It also eliminates all the problems of pickup tubes: clogging, cracking, breaking, etc. The downside is the risk of tank fitting leak.
Some companies build their pickup at mid-tank level. Mid-tank pickup has all the disadvantages of both top and bottom pickup and none of the advantages. I strongly recommend you do not accept mid-tank pickup.
RECOMMENDATION: Top or bottom pickup is acceptable, I personally prefer bottom pickup.