I just had to redo a soil and sand tank. Messy! But... most parts of dirt float in water, even if only for a very short time. So I put it in a bucket, stirred, and poured the water out, after giving the sand three Mississippis to sink, and it's like pouring out liquid dirt. However, regarding weight/ density/ mass/ whatever of EC and it's ability to sink, I have zero experience with it as I can't afford the stuff, so I don't know how this will work for you. It worked for me because sand is the part of dirt that sinks first (then clay, then silt I believe), although it did still take about a dozen gallons of dechlorinated water to get the sand clean clean.
Not just clean d=')
I used dechlorinated water to save any beneficial whatever because I reused it when I set the tank back up. Of course there is no saving it all, some of the sand will just get mixed in to the dirt, which will hopefully be used for another tank (if I don't continue to fail like I have been with the plants).
By the way... I felt the need to redo because my betta was acting sickly outta no where and I was worried about the fact that despite stirring the cap/poking it everyday for the month or so it was going, the bubbles would not stop. Granted, I don't have any MTS (yet), and I've lost about half the plants I started with so it's nothing close to heavily planted... but I also forgot to sift and had started some very woody stuff, I was worried about gas pockets. I will NEVER not sift again!!!
Hope this helps if you do decide to start over.