i understand that majority of people go for sump tank or IOS at least and it seems like only a small number go for canister.. my question is what are the other disadvantages canister filter has other than having lesser total water volume as compared to sump? does clogging of wools and media inside a canister increase nitrate? And isn't IOS similar to canister filter just that its open-top? i understand sump and IOS can have skimmers/refugime but canister cant.. there isn't much info here in SRC