Did mine yesterday. Used submersible pump and tubing from gfo/ carbon reactor to pump dirty water into a 5 gal bucket. Only light cleaning the loose stuff in the skimmer and return pump chambers. Leaving overflow return which has live rock/ceramic bio balls and refugium chambers alone. Can’t siphon the sump, it is nearly ground level. 30 gal Fiji sump. I’ll do10 gal water change of sump water when I lightly clean it. Fish never know what happened. Also use same pump and tubing to pump 10 gal of clean water back in the sump.I did some sump maintenance today, and I found the bottom has a considerable amount of decayed matter which I would like to get out.
You can't use a siphon (gravity; thou art heartless), so what else is there; a net?