To clean the rocks in your aquarium, mainly the substrate of your aquarium is going to be typically rocks, gravel, and you're going to want to clean that on a regular basis. Every three or four weeks when you do your good water change you want to siphon the rocks in the aquarium.
So, a siphon is basically something you'd buy at a fish store. It has a gravel tube roughly two inches in diameter, maybe eighteen to twenty-four inches long, and that's connected to like a six to eight foot length of half inch or three-quarter inch flexible tubing. The tubing's going to go in a bucket, the gravel tube goes in the aquarium, and you're going to get a siphon going. Once the siphon starts water is now siphoning out of the tube into the hose into the bucket. Be very mindful that the bucket doesn't overflow.
I don't recommend siphoning directly into a sink. You'll find some 50 foot pythons and stuff. Those are good if you're very careful, but if you suck up any gravel or sand it's going to go right into your drain. And it's going to clog your drain and it's going to result in an expensive plumbing bill. I like to see what I'm siphoning out of the aquarium go right into a bucket so I have good control.
That being said when you're siphoning the aquarium remove some of the decorations, and just go nice and slowly through the sand bed. Do it in a zigzag pattern so that you can see where you started and where you finished. You don't want to just go haphazardly through the gravel bed or you're not going to clean efficiently.
Kind of like vacuuming. You just don't go all over the floor. You start in one corner. You work your way to the other so you do the entire perimeter.
You also don't want to go too fast because you don't want all the waste to just get blown into the water column. You want to trap all the waste into the siphon tube so it all goes into your bucket. That's the goal, to remove a lot of the waste that's in that gravel bed.
And then after you've changed 15 to 20 percent of the water you're going to replace that water with good, conditioned, filtered fresh water of the same pH and same temperature so you don't shock the system. The same rules apply to salt water. You just want to match the salinity and the pH before you put that salt water back in the aquarium.
With fine sands this video doesn't really apply because we're talking about gravel, but it's the same principle. You'd want to siphon the sand like you would the gravel, but you want to use a lot less water volume, a lot less flow through the siphon. Otherwise you'll suck all the sand out.