Well I have been raising fishes for a long time now, about 10 years I guess, and I have a 350 gallon tank that is new, and I have lots of gravel, and my 200 gallon is filled with sand

and my 29 gallon is just filled with gravel.
I have a huge siphon that has a very strong sucking system. It gets the waste out very quickly, and the gravel just spins around and the waste stuck to the gravel gets out
Also, for my sand, I turn the sucking speed to a very very low setting, so it doesn't suck up a lot of the sand that much

I still have to put in some new sand once in a while.
Also, you don't have to move the decorations in your aquarium because you'll just create more waste to the aquarium.
Also, if you want. You can use a siphon that has a sucking speed that you can easily change. It's real great
I have a lot of gravel in my 29 gallon, and it i about 2" deep, so it helps with my plants to root themselves in. Also, I have to dig down in the the gravel so then I can get all of the waste out
Also, I set the siphon sucking speed to medium-high level on it.
It's good to siphon the tank a lot, because it helps with all the waste being sucked out
Also, just like a river, the waste gets washed out, and for the tank, the siphon gets the waste out

same thing eh?