I'm having THE hardest time keeping the edges clean of algae. I use the Mag-Float scraper for my glass tank and it get everything on the main areas of the front and sides. However. it's d@mn near impossible to keep the edges clean.
So how do you keep your edges clean? Do you just manually scrape it? Use a special type of scraper?
Mighty mag is the shiznit!
Scrapers are good for corners, also, if you wanna live on the edge you can use boiling RO water with a turkey baster to kill off the algae, it works great for coralline algae, just go slow with the bastering and keep the H2O close to the algae and away from coral.
I am pretty paranoid about magnetic scrapers after getting a piece of sand in one and scratching the acrylic.
When you do it by hand, the only part that touches the acrylic is the scraper blade, so no way to get sand stuck there.
Even the pads are safer done by hand, due to thickness. The hand-pads are very thick, so sand will simply be pushed
deeper into the pad, not pressed against the acrylic. And of course, eventually washed out, since it is common to wash
a hand pad, but usually mag-pads are left in the aquarium.
And on topic : Corners, even rounded ones, are generally a non-issue when doing it by hand.
Ahhh, someone that has not tried the "Super Algae Sock", it works great along the sand line 
I use a plastic scraper and manually get it, but there must be a better way.

Ok, I did some searching, and seems the "Super Algae Sock" is now the "Super Algae Cutter", on the mighty magnets site.
But ouch, for my 3/4" acrylic, looks like I need an "F-4" at $180.
That is for the whole magnet setup (i got the next one down). It's great, but you can also just use the algae sock on your hand like a sock puppet 
I use the Mighty Magnet sleeve by itself. Cuts algae away like nothing. Mighty Magnets are a good arm and a leg compared to a Mag-Float but definitely worth it.
http://mightymagnets.com/pads.htm#cutter
John