Yesterday I cleaned about 5 cubic feet of new gravel. In the past I have used progressive tubs and a bucket filled with holes. I would start at one end and work my way down three or four barrels of progressively cleaner water. This proved to be insufficient and the barrels became quite dirty very quickly which meant that I would constantly have to start over with more clean water.
But yesterday I used a small cement mixer. I'd put 10 shovel fulls of gravel in and filled it with water. Then turn the mixer on for 15 seconds, and dump the water. I did do this about 7 or 8 times until the water was running clear.
This next step may not be necessary, but then I did a final rinse in a white bucket. I was able to easily see how clean the water was in the white bucket, and two quick rinses generally finished the job.
It took a few hours to perform this cleaning, but after several bad experiences with cloudy water, I'm very happy with the results. Today my water is perfectly clear.
A couple months ago I added 10 feet of 1-1/4" pipe to the line from my fish tank to the grow bed. It has worked well until recently when I noticed that the water in the fish tank was beginning to raise. Closer inspection of the pipe revealed that gunk had built up on the surface and was slowing the water down. I replaced the pipe with a clean 2" pipe. I'll let you know in a few months how that worked out. I'm feeling confident that this is going to work out much better. As a general rule I'd say 2" or larger pipe should be used everywhere.