It has always been a problem when doing a DIY Calcium Reactor, Media Reactor or Kalk Reactor as to how to obtain easy access to the inside of the cylinder and still maintain an water tight seal. When using PVC because the male threads of any fitting are typically tapered they do not tend to tighten completely down on a female mate. You also add a lot of unneeded height to a project by adding threaded couplings that are not always very easy to get off at best. Blake demonstrated the use of compression cap that can be gotten at Home Depot that works great by allowing easy access along with no additional height added to your project. Be sure to replace the compression screw with a stainless steel screw.
Chris, we know how you are about "scratching" yourself during DIY projects, so it concerns me when I see the caution "STAND CLEAR WHILE IN USE" printed on the cap. Wonder what that will lead to !!!! Great idea Blake, I can see several applications in a cap like that.
I haven't looked at Home Depot specifically, but I know Lowe's carries these caps. The bolt is a carriage bolt. For the 4" cap, the replacement bolts were around $3.50 for two of them.
