If you have a tank with one or more overflows built in, don’t forget to vacuum them when you do your regular cleaning. While you might think that all detritus either gets sucked into the filter or rests on the substrate, some can and will slowly accumulate on the tank bottom inside the overflow chamber.
In this post from almost a year ago, I mentioned that I use a prefilter sponge over the overflow intake on my 75g tank. Though this will prevent nearly all detritus from reaching the filter, waste will always find its way to the bottom of the overflow. If you test your water parameters and you notice that your nitrates are creeping up, check your overflow for build-up. That could be a contributing problem.Your substrate vacuum (Python or whatever you use) may or may not reach the bottom depending on the plumbing, the size of the overflow chamber, etc. If it doesn’t reach, just assemble a small PEX vacuum and clean the overflow using gravity siphon.