I can not find this information anywhere. What is the critical level for a sump pump. In other words, how high can the water level be in the sump pit before it affects the concrete it is sitting against. Should the water be pumped out when it is one inch, two inches etc. below the top of the floor. Example: if I let the water rise to a level of two inches below the basement floor my pump never runs and the water of course does not continue to rise. Is this safe for the concrete or should the water continue to be pumped out below this level?
Re: Sump pumps
It's not clear as to the setup for your sump pit and pump.
For example here our sump pits have to be 30 inches deep with the drain / weeping system tied into. Obviously in this case the water level would need to be below the opening of the drains which are well below the level of the floor. Usually only a few inches of standing water is left in the pit at any time. This also allows a safety margin when there would be a heavy water flow so as not to overwhelm the pumps output capacity to discharge.
Depending whether you have a submersible or column pump there are adjustments that can be made to allow it to come on and shut off.
By moving the pump down further into the pit will also determine how much standing water level would be. On a column pump there is also a slide adjustment along the float shaft to engage and disengage the switch. With the submersible lowering the pump will allow the float switch to turn on and off earlier.
In your case I wouldn't have the water level as high as you .... depending on how deep your pit is you might consider dropping the level 6-12 inches or more.
Just a thought.:)