Set up help please! 110 acrylic overflow box leaking

[CichlidZ67]

Setup help please!! I threw my live sand in and started filling last night. 10 gallons in and realized my overflow box is leaking. Acrylic on acrylic. Advice on how to seal without taking my whole build apart? I have Weld On #16. Will a bead of this messy stuff work? Finally got the wife involved and she did the fake plants and rockwork. Thought I'd have fish this weekend

 

[CichlidZ67]

Emptied the water and moved sand. I can see the leak that goes into overflow box. Poured a big gulp cup of water into the overflow. Look at bottom left corner. Water trickling under.

 

[Hari Haran]

#16 should be fine, just have the tank at an angle so it covers both top and bottom once cured like an triangle.