What to use to hold Acrylic together?

Yes, you should use acrylic cement. A common acrylic cement brand is "weld-on".
 
You can go to any pet store and they should have this it's called All-Glass Aquarium Silicone it comes in black and clear and you can find it by the Algae scrapers works really good.
 
You can go to any pet store and they should have this it's called All-Glass Aquarium Silicone it comes in black and clear and you can find it by the Algae scrapers works really good.

Sorry for double post, I forgot to add to my previous post.

I don't think you are suppose to put silicone meant for glass onto acrylic. There is separate stuff, just don't know what. All-Glass Silicone is meant for glass.
 
Acrylic cement is not harmful to fish in any way. After joining the pieces of acrylic together it will be completely gone.
 
You can go to any pet store and they should have this it's called All-Glass Aquarium Silicone it comes in black and clear and you can find it by the Algae scrapers works really good.

Silicone does not hold to acrylic very well. The only way to join acrylic together is by the use of acrylic cement.
 
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