With any vinyl tubing, select material with greater wall thickness
as opposed to thin wall thicknesses. This helps prevent kinking
and collapsing, the two primary downfalls of vinyl tubing. Avoid
placing heavy objects on tubing and be wary of burying it in
deep excavations. Despite its limitations, vinyl works well when
used in situations consistent with its capabilities.
As the pump flow-rate increases, the need for larger diameter
tubing arises. For diameters larger than one inch (2.5 cm), a
pond builder has two basic choices -- rigid PVC pipe and flexible
PVC tubing. They handle large-volume water circulation. Flexible
PVC tubing uses either glued or non-glued fittings. Environmental
conditions, complexity of the plumbing system, pipe lengths and
budget all influence the choice of rigid or flexible PVC.
Since pipe diameter largely dictates flow rates, picking rigid
or flexible PVC may not seem much of an issue. However, it becomes
an issue when you insert fittings into the equation. Flexible
PVC readily bends, eliminating curved fittings that rigid PVC
requires. Each fitting adds to the total dynamic head, reducing
the output of the pump at a given height. In addition, flexible
PVC comes in lengths up to one hundred feet (30.5 meters) in
the US, eliminating coupling pieces of pipe together on long
Another advantage of flexible PVC comes from its elastic structure.
In cold weather regions, flexible PVC withstands freezing conditions
that would rupture rigid PVC. While I do not recommend allowing
any piping system freeze with water in it, flexible PVC is more
forgiving. It also can tolerate heavy loads placed on the pipe,
so you can bury flexible PVC without worries of damage.
While ideal for many jobs, flexible PVC does cost more than
rigid PVC. Flexible PVC that incorporates barbed fittings to
make connections is less expensive than the glued fitting pipe.
However, the downside is thinner wall thicknesses, less selection
of pipe diameters and the hassle of switching between barbed
hose fittings and threaded component fittings. Fittings are potential
leaks if not installed correctly. Barbed fittings combined with
hose clamps are far from foolproof. Finally, the curved nature
of flexible PVC presents problems when making connections on
short, straight pipe runs. Patience and a heat gun help, but
beginners should understand some plumbing jobs might require
For many water gardens and koi ponds without complex filtration
systems, flexible PVC may seem a logical choice. Nevertheless,
in applications with multiple filters, bottom drains, settling
chambers and manifolds to direct flow to the proper destinations,
rigid PVC gains the upper hand. Plumbing a filtration system
with multiple components usually involves fitting a maximum amount
of equipment into minimal space. Short pipe runs, tight clearances
and sharp angles necessitate exacting precision, which rigid
PVC delivers. Most hardware and home centers carry a wide assortment
of rigid PVC fittings and pipe diameters suitable for water gardens
and koi ponds. Just like flexible PVC, working with rigid PVC
requires basic plumbing knowledge and skills. Do not be afraid
to seek knowledgeable help. Ready availability, ease of use and
low cost all steer many beginning ponders to the rigid PVC aisle.
Rigid PVC does have limitations. Exposed piping tends to be
difficult to disguise, especially around a pump or filter located
within the pond. As mentioned, rigid PVC may crack or shatter
under pressure of copingstones or from being buried. Ground heave
presents another concern when burying rigid PVC. Most damage
occurs at fittings. Finally, extreme environmental conditions
such as high temperature, UV exposure or extended freezing periods
may cause early failure of unprotected rigid PVC.
Despite their differences, all tubing types share some things
in common. Flexible and rigid PVC use the same glued fittings
while vinyl and non-glued flexible PVC use the same barbed fittings.
Any system benefits from check valves, ball valves, unions and
quick couplers to make maintenance and repairs simpler and to
improve overall performance. Always use the largest diameter
pipe the system might require, just in case you later add an
upgraded pump. Lastly, research suppliers for quality, warranty,
service, reputation and knowledge as well as price. Like other
pond materials, pipe quality varies greatly among manufacturers.