Little did most of us know when we first entered the reef aquarium hobby that we would quickly become proficient plumbers. Between plumbing sumps, multiple systems together and simply performing water changes, the world of aquarium plumbing can quickly overwhelm newcomers and salty veterans alike. Through the years I’ve plumbed hundreds of aquariums, dozens of water changing systems and have inhaled enough PVC cement fumes to inebriate a herd of elephants. This post covers some of the ‘trade secrets’ that aid in efficiently plumbing any system with Poly Vinyl Chloride (PVC), and can help establish of plan of action prior to necessitating fifteen trips to your local hardware store.First let’s look at the various types of PVC used in our hobby. Upon inspecting PVC options there’s no doubt that you’ll encounter several wall thicknesses of tubing and fittings. The main two wall thicknesses we commonly deal with are Schedule (Sch.) 40 and Sch. 80 PVC. Wall thickness determines the maximum pressure the PVC tubing/fitting can handle. Even with high pressure rated pumps we aren’t coming close to approaching the maximum pressure rating of Sch. 40 PVC in home aquaria, so why even talk about Sch. 80 PVC? Aesthetics. A few years ago we started to witness a plethora of builds being shared on reefing forums utilizing gray Sch. 80 PVC which looked great by avoiding unsightly white PVC with obnoxious lettering printed all over it (note most Sch. 80 has black lettering however it blends into the gray). It’s important to realize that we are deterring flow by using Sch. 80 PVC, and certainly raising the cost of our build considering many Sch. 80 PVC fittings cost double or triple the amount of Sch. 40. For the most part Sch. 80 is used strictly for looks, but there is something to be said about Sch. 80 PVC valves. They’re built more robust than their Sch. 40 counterparts which will aid in longevity. We’re now starting to see more offerings of colored PVC; black is available from several suppliers (Savko being my go-to) and colored PVC options from Pimped Out Aquariums. Ultimately the choice between Sch. 40 versus Sch. 80 plumbing is a personal opinion. When planning your plumbing make sure to utilize unions wherever necessary. This allows painless removal of pumps and other equipment for maintenance, along with easing any dreaded aquarium move that may take place in the future. Over time detritus, sponges, snails, worms and other things will slow PVC flow to the point where they need to be replaced, and unions will make that task effortless. Every few months I detach unions and remove the o-ring inside to lube up with some petroleum jelly ensuring they stay pliable. I’ve never had a properly seated union leak. It’s been said before, and I’ll say it again, measure twice cut once. This can be easier said than done in practice when connecting manifolds to multiple pieces of equipment, and for this reason I always pick up a few extra slip x slip unions, just in case. Once measured, make a mark on the PVC, pick up your tool of choice and go to town. A pair of PVC cutters and my trusty reciprocating saw is kept within arms reach while on a job site. I employ PVC primer and cement on every slip connection (versus threaded), no matter the size of PVC. Many places only recommend the use of PVC primer being necessary on sizes 1.5” and larger, however I feel the benefit of utilizing primer is certainly worth the time and cost. Primer softens PVC to the point of almost fusing parts together without the use of cement. When coupled with cement you have a permanent installation that will not fail. Prior to gluing pieces together however, I always ‘round’ sharp corners of the freshly cut tubing. This allows tubing to slide into fittings without creating any channels in the fitting. Cut tubing will have an incredibly sharp 90° corner that can gouge a channel into the fitting that will result in failure. I also round corners of flex-PVC or Spaflex as it helps tubing seat and avoid pushing out of the PVC fitting. You can use a razor blade, pocket plane or file to easily round corners. I try to avoid threaded fittings whenever possible, as I feel they have a higher chance of failure compared to a glued joint, which I consider permanent. Occasionally you will run into a situation where threaded fittings are necessary, at which time I employ aquarium grade silicone over the perpetually infuriating Teflon tape or incredibly sloppy pipe thread sealants available. Of course this does necessitate ample drying time (~48 hours) so planning ahead is imperative. If I’m in a pinch on the road I’ll reach for the Teflon tape, although it has to be a do-or-die pinch. Eliminate the use of check valves unless absolutely required. It’s not if, but when will a check valve fail. I’ve seen some pretty insane plumb jobs that heavily rely on check valves that would result in water everywhere and a complete loss of livestock unless tended to immediately. If for some reason you feel the need to utilize a check valve, spring for the transparent double union (or “Wye”) units that can be visually inspected and replaced when necessary. Finally here’s a video I put together showing the various tips in practice.