You can do that, but it's wise to have a secondary path. Less for concern over the algae growing into the slot/screen junction than it is for concero that something might go down the overflow pipe and get snagged on the screen or block the slot.
If you have dual overflows or a herbie/bean drain, less of a concern. Otherwise you can create a bypass on the drain, but you have to allow for some head pressure to build up on the slot/screen junction instead of allowing it to just completely bypass if there is any backpressure...
If you have dual overflows or a herbie/bean drain, less of a concern. Otherwise you can create a bypass on the drain, but you have to allow for some head pressure to build up on the slot/screen junction instead of allowing it to just completely bypass if there is any backpressure...