Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Heavy things like gravel get sucked up into the large tube, swirl around a few seconds and drop out. You can go over the whole tank and get it really clean all the way down and not lose any gravel.
The finer gravel will also do this, but sometimes a bit will go out the siphon. Not often, but if you are running a large siphon it can mean quite a bit of lost gravel over time.
Sand can get removed from the tank with the mid-sized siphons. If I want to deep vacuum it there are several tricks I use:
1) Put the bucket higher up, not on the floor. Water runs slower, so sand can drop out of the large tube.
2) Hold the outlet tube in my hand, ready to pinch it off. Stop or greatly slow the water flow and the sand drops out of the large tube.
3) Hold the large tube at an angle so the intake is no more than half buried in the sand. Then drag it through the substrate, do not push it.
I will do a similar method when I am moving or re-scaping a tank, and want to thoroughly clean Soil Master Select or Turface. It also is a lightweight substrate that can all too easily get inhaled by the siphon.
I do not generally clean a planted tank that deeply. I will use a piece of tubing that is just a bit larger than air tubing and move this through the plants if I see something I want to remove. It is slow enough flow that the leaves are not trapped in it.