hi, i currently have a 45cm long tank housing cory hasbrosus and cory hastatus. the tank is filled with sudo fine sand. for the shifus keeping corys, how often do you clean the sand? is there even any need to do so? currently, i use my tom's gravel cleaner to clean up any poo and debris i see every week, which takes about 20 mins. its quite tiring to do so but it gives me satisfaction to know my cory tank is now "clean". just wondering the best way to maintain a corydora tank. all inputs are appreciated!