weld on 3 work best, i used that to build my 270gallon acrylic frag tank. my tank is been up and running for 7 months, no leak and still running strong. you can get them at craftics plastics as mention above or southwest acrylic on princeton and candalaria near SWR too. you also need a syringe bottle to apply the liquid to your acrylic. if you need some weld on 3 or the syringe bottle let me know. still has plenty left from my last project.