How Bad Is Algae Got In Tank Seam?

[seabear]

I have this fish tank for almost 20 years. There are a couple spots with algae got in the tank seam. I am not planing to repair the tank seam since I have no room to do it. Anyone know how bad is this and how long usually a fish tank can last?
http/s1052.photobucket.com/albums/s453/Ditto813/?action=view&current=IMG_3636.jpg#!oZZ1QQcurrentZZhttp%3A%2F%2Fs1052.photobucket.com%2Falbums%2Fs453%2FDitto813%2F%3Faction%3Dview%26current%3DIMG_3636.jpg

 

[deathy]

Generaly whenever I've had that itsbeen surface algae have you tried cleaning it with a sponge, just don't be rough on it.

 

[seabear]

Hi deathy, I tried but couldn't get rid of them, it seems like those got in the silicone and if you look at the picture you can see the darker spots within the silicone. The spots are slowly getting bigger in a year, I am afraid it will continue damage the seam and cause leak later. Is there a way I can kill those algae to stop the spread?
I live in an building on 5th floor, I don't want to have an accident…

 

[cynic]

What about a blackout. 4-5 days of total darkness. Fish should be fine and plants will be ok but the algae should die off.

 

[seabear]

I need to wrap paper around the fish tank in order to have total darkness, right?
If I can kill those algae is the seal going to be safe or it's still a concern because the damage was done. The algae spots is about 5mm to the joint of the left side glass.