Filling a gap in acrylic tubing

[causeofhim]

I broke the riser tube off my sump box on my ETSS 800. I am planning on putting it back together with Weld On 3 but realised that I am missing a small piece of acrylic. The piece is about 1/8" x 1/2". What can I use to "fill" this gap?

 

[big t]

put some masking tape on the inside, and fill it w/ weldon 40. It may take 2 seperate applications but after that it will be water proof. It will probably craze it a little, but it will be fine.