Folks:
I know this is coming from "way, way out in left field" but
I have
1) a mainly laterite substrate overlaid with 1" of uniformly graded gravel;
2) a planted tank;
3) a "bunch of 'cleanup' fishies" and
4) a "ton" of biological filtration media in my filtration process.
I do not believe that the following is applicable for everyone's tanks!!!
BUT
I believe that the fish waste on the gravel, which I also believe "filters down to" the substrate and contributes nutrients for the plants and
I therefore only vacuum the bottom of the tank when the "small dead snail shells become unsightly".
I can only recommend this "strategy" if the biological filtration media for the aquarium is "like 5 times" what is necessary for the tank and
the turnover rate is somewhat higher than the recommended turnover rate.
Please note that since I ceased "overfeeding" I have not observed an ammonia or nitrite concentration in my tank employing this strategy.
TR