The most commonly used plastic pipe cement in the koi world is (pipes weld on 725 wet or dry)
it as a very fast curing time and a very good applicator,so make sure your measurements are correct before applying the cement,A small electric chop saw is ideal for getting the cuts perfect,or a good quality PVC pipe hand held saw.

Use a good ABS pipe cleaner to prepare the joint to be glued,such as Griffon solvent weld cleaner or Astore cleaner,wipe any burs from the plastic pipe and also inside any joints or unions,the cleaner will also take off any stubborn excess glue. 

The Griffon Uni-100 is a slow reacting solvent weld glue and is ideal for the most trickiest of jobs,when you need a little time to line things up ,most of the other solvent weld glues go off really quickly.all the solvent weld glues that we supply come with really good Integral brush for easy and clean application of solvent.