DIY vacuum for sump cleaning

So I was looking at my sump and the bottom has a nasty layer of gunk from when I was filling up the fuge portion with sand. I need to clean this out however not sure of a cheap and easy way to do this since siphon is out of the question (sump on bottom of floor). Are there any good ideas for maybe making a vacuum or hand pump? I noticed those python siphons but it sounds FW only since it dumps water back in your tank.

 

The python uses a venturi that connects to your sink. It removes water and dumps it down the drain exactly the same way a water bed fill kit works, nothing goes back into your tank. I use a python to remove detritus build up from my sump.

 

I read it wrong then. So I can utilize this to clean my poor dirty sump and suck some algae off the rocks. I assume the sucking power is controlled by the speed the sink can pour?