Water pumps are meant to pump water.
When you introduce debris and other solids to the mix, things can get stopped up.
This is where trash pumps come in. They're capable of passing water containing these sorts of elements.
The type of water you'll be pumping will determine which type of trash pump you'll need.
Semi-trash pumps get their name from the fact they can pass small debris, but not much more than that. The pump housing just isn't large enough to pass larger items.
The largest items any of our semi-trash pumps can pass is about 5/8 of an inch. Semi-trash pumps are typically used to pump clear or slightly muddy and sandy water.
You'll want to use a hose with a strainer so the hose doesn't get clogged with any items too big to pass through. The strainer just sifts the debris that the pump can handle and leaves out the stuff that's too big.
Don't throw a trash pump hose into a trash can and expect it to work. Rather, trash pumps are made to handle debris and solids such as leaves, pebbles and twigs.
With larger impeller veins and pump housing, trash pumps can pass solids like those mentioned above. The pump does not grind these up as they enter the impeller, but leaves them intact and sends them on their way.
You'll want to use a hose with a strainer for trash pumps too. In the event the pump does get clogged though, there are easy clean outs, which you can open up by hand and remove any items too big.
Diaphragm pumps work entirely differently than other trash pumps. Instead of using centrifugal force, the pump has a diaphragm which is pushed up and down, creating a vacuum effect.
When the diaphragm goes up, it creates a vacuum, sucking in water. When the diaphragm is pushed down, it ejects the water that was just suctioned into the pump. It essentially acts like a piston in a combustion engine, alternately drawing in and then ejecting out.
Diaphragm pumps are most commonly used to pump sludge and extremely abrasive liquids. A common example would be draining a pond because it can handle the muck and mud on the bottom, as well as the water, leaves and weeds.