Skip to content


Home / Blog / Hydrostats, Coping, and Other Parts You Never Knew Your Pool Had
Hydrostats, Coping, and Other Parts You Never Knew Your Pool Had

Hydrostats, Coping, and Other Parts You Never Knew Your Pool Had

If you own a swimming pool you are pretty familiar with the basic terms for your pool. You have a pump, a filter, and maybe a heater. Your pool has walls and a floor, steps to get in, and a deck surrounding it. But some parts of your pool may be a little less familiar. Here are a few pieces of your pool you never knew about, although they may have been hiding in plain sight.

Hydrostats, Coping, and Other Parts You Never Knew Your Pool Had [infographic]

Pool Coping

Coping is a term you may not be familiar with, but if you have a concrete pool it’s staring you in the face every time you use your pool. Simply put, coping is the edging around your pool. It’s that strip of material where the edge of the deck meets the walls of your pool. When you get out of your pool on the deep end, the edge that you pull yourself up on is the coping. Coping can be a decorative feature, framing the pool. But it actually has a very important function.

The first function of coping is to cap the concrete walls of the pool. The coping covers over the upper edge of the walls,  concealing and protecting the bond beam (we’ll get to that later) and any metal that projects from the walls. The second function is to direct water that splashes out of your pool onto the deck and away from the pool. You may have noticed that the lip of your pool coping is slightly tilted back away from the pool. This directs any escaping water back toward the deck drains.

Coping Materials

Coping can be made of a variety of materials. The most common is precast concrete stones. These stones, in straight, curved, or corner sections, are typically grayish white and porous. In addition to redirecting water, they have another use. This common style of coping provides a rough non-skid surface around the edge of the pool. That helps prevent falls and makes it easier for swimmers to get in and out of the pool.

Custom and decorative coping is also available in a wide variety of styles. Coping can be made of paving stones, brick, or other custom materials. For a crisp modern look, some designs do away with coping altogether. Instead, the pool deck can be extended a few inches over the edge of the pool walls out over the water.

Bond Beam

“Bond beam” is a term from masonry. It refers to a horizontal structure usually embedded at the top of a masonry wall. It is used to provide horizontal strength where there is no support from a floor or roof structure. In a concrete pool, and sometimes in a fiberglass pool, the bond beam surrounds the top edge of the pool, reinforcing the top of the pool walls, which are mostly underground. It usually consists of poured cement reinforced with rebar.


Hydrostat is short for hydrostatic relief plug. A hydrostat is crucial for a concrete pool. Hydrostatic pressure is the upwards pressure created by groundwater. Usually, the weight of the water in a swimming pool is sufficient to counter the upwards hydrostatic pressure of the ground water beneath the pool. However, when the pool is drained the hydrostatic pressure is no longer countered. This could lead to upward pressure that could crack or damage the floor of the pool.

To avoid damage from upward hydrostatic pressure, pool builders include hydrostatic relief holes. A hydrostatic relief hole consists of a hole in the bottom of the pool with a pipe that goes down into the ground. At the base of the pipe is a gravel filling. If groundwater is exerting upward pressure, the groundwater can flow up through the hydrostatic relief hole and into the drained pool, relieving the pressure below. These holes are usually covered with hydrostatic relief plugs that are plastered into place. When a pool is drained for maintenance, the plaster is chipped away and the plug is opened to allow groundwater to bubble up if necessary.

Some commercial pools and high-end residential pools use automatic hydrostatic relief valves. These valves are spring loaded instead of being plastered into the floor of the pool. This allows groundwater to flow out into a drained pool if the upward pressure is strong enough. When the pool is filled, the weight of the water holds the valve down and sealed shut.


A weir is a term from civil engineering. On a large scale, a weir is a low dam built across a river, usually to raise the water level of the river upstream from the weir. Typically, water is allowed to flow over the top of the weir in a sort of artificial cascade.

In your pool, you’ll find a much smaller weir in the mouth of your skimmer. When a pool’s pump is working, water is drawn in through the skimmer. From there it is directed through a filter and then to a heater if there is one. After that the water is circulated back into the pool.

The weir is the small floating plastic barrier at the entrance to the skimmer on the pool side. The weir keeps the skimmer from just sucking in pool water, and instead allows only a thin sheet of water to spill over into the skimmer. Ideally, this thin sheet of water carries twigs, leaves, and other small floating debris into the skimmer. Once in the skimmer, they can be caught and contained in the skimmer basket. When the pool pump is turned off and the suction stops, the weir floats into a vertical position and prevents the debris in the skimmer basket from washing back into the pool.


Turbidity is not technically a part of your pool. Instead, it describes the state of the water in your pool. Turbidity is basically a fancy term for cloudiness in a liquid. Turbidity is caused by a large number of particles that are individually too small to be seen by the naked eye. When a high enough concentration of these particles is present in the water, the water can take on a cloudy or hazy appearance. This is similar to smoke in air, which is really a collection of tiny particles that are individually to small to see.

Turbidity in pool water can be a problem. The particles that cause it are so small that they are not captured by a standard pool filter. The solution is to add a clarifier to the pool water. A clarifier works by causing the tiny particles to coagulate into larger clumps of particles. These larger clumps can be caught by the pool’s filter. This clarifies the water.

Are There Other Things You Don’t Know About Your Pool

In the words of Donald Rumsfeld, “there are unknown unknowns…things we don’t know we don’t know.” You may know a lot about your swimming pool and how it functions, but the things you don’t even know you don’t know can get you into trouble. If your pool is giving you trouble and you’re not sure why, it may be time to call in the pros. Thankfully, the professionals at The Pool Butler know a whole lot about your pool and can help keep it in perfect condition, even if you’re not sure why it’s having problems in the first place. Contact The Pool Butler today for a free consultation. We can demystify your pool and solve your problems.

The Pool Butler