i'm actually being a bad, bad man. i know it's not recommended to overstock, but i've got 9 platys in a 10g tank.. the little male survivor we got with the 30g is staying.. he's happy & deserves a good home after making it in that tank.. so i clean the tank completely 2 or 3 times a week and keep just a thin layer of marbles for the only substrata to make it easier to suck up poop with the turkey baster every day or 2, if needed.
The tank has crystal clear water and 0,0,5 for the water chemistry today.

4 of the platys are tiny balloon platys though and are probably going to equal as much as 2-3" total adult size and the 5 other platys come up to about 10" so it's not too far over and the extra cleaning keeps it good.
that little guy might do fine on his own.. this guy we inherited was by himself in real bad conditions and is doing alright.. possibly internal parasites but i'll test that with red color pellets tommorrow before treating him with parasite clear if i have to.