what size aquaclear do you have and on what size tank?
Flow will slow down as the sponge gets clogged, this means it is doing its job catching gunk. You can rinse the sponge in old tank water every week to clear the gunk out. If your sponge is clogging to quickly after cleaning it, then you probably don't have enough mechanical filtration for your tank. For example, your fish my be producing too much waist for that filter, and you may need to either add a second filter, or get a bigger filter.
Also clean the intake tube with whatever you can use to 'get up in there'. They make cleaners specifically for filter tubes, but it is cheaper to buy a baby bottle brush, that's what I use. You only have to clear the filter tubes if they are clogged, algae growing in the filter tubes won't really hurt anything and is probably good for biological filtration.
Hope this helps!