Yes good point, I would also use a cheap or older net, the grass tends to stick to the net and you spend ages picking it out, or at least I do, another option which is harder you can trim at the same time as a water change so the off cuts of grass go straight up the siphon (can also be used when trimming moss too) but it is much harder to do I usually trim it down to about 10mm or 1cm I have also by accident cut it within 2mm or so of the sand, but it still grew back as strong so I wouldn't worry if you cut it too short