Swimming Pool Flow Meters Guide

Summary: A swimming pool flow meter is a device that tells you how quickly the water in your swimming pool is circulating through its plumbing system.

Like most homeowners, you want to find ways to save money on the maintenance and upkeep of your home. When it comes to your swimming pool, a little bit of know-how can go a long way toward keeping your money in the bank.

One piece of equipment that can keep you alert to issues with your pool and its plumbing and mechanical systems is a swimming pool flow meter.

Understanding how well the water is circulating is essential, and a flow meter is much more reliable than waving your hand past one of the returns to gauge the force of the water coming out of it.

What Is a Pool Flow Meter?

A pool flow meter is a device that tells you the speed of the water circulating through your swimming pool’s system. I refer to the plumbing and mechanical aspects of a pool collectively as a system.

Why Should You Use a Pool Flow Meter?

You should use a pool flow meter to keep the pool guy out of your wallet. The significant benefit of installing one on your pool is that at a glance, you can see if something is affecting the circulation of your swimming pool water. Good circulation is essential for a few reasons.

First, you want your pool’s water to routinely and thoroughly cycle through the filtration system. This circulation is how you ensure that the filter media mechanically filters all your water.

Larger debris will end up in your skimmer baskets, and your filter will catch smaller debris. If you have poor circulation, you will have to run your filter much longer to complete filtration.

Second, good circulation will ensure that your pool’s water receives adequate sanitization. The sanitizing chemicals you use need to be well-distributed to kill any contaminants.

It doesn’t matter if you have a saltwater chlorine generator, liquid or tablet chlorinator, Ozonator, or UV sanitizer. Good circulation helps expose all of the water in your pool to your sanitizing agents, ensuring that all water is treated adequately.

Finally, good circulation is essential for maintaining the temperature of your water. Even without a heating system, the sun’s energy will warm the surface water of your pool.

Without adequate circulation, the colder water on the bottom might never mix with the warmer air on top, leading to swimmers being uncomfortable. And if you have a heat pump, solar, propane, or gas heater, you want to ensure that the money you’re spending heats all of the water, not just some of it (for more on heaters, read my guides on the best pool heaters and best solar pool heaters).

Different Types of Pool Flow Meters

There are different types of flow meters available to purchase. To choose the right one for your pool, you need to know your pipe size and what it’s made out of.

The vast majority of pools feature PVC plumbing, so that is probably an easy question to answer. We care about pipe size because it is part of the equation that determines your flow rate.

Your pool pump sucks the water out of your pool, pulling it into the skimmer. Then it travels through your pipes and into the pump. The pump pushes the water out and into the filter.

The water in the filter is pressurized and forced through your filter media, most filters have a little gauge on top that shows the pressure reading, so you can determine when it is dirty and needs cleaning.

Finally, the filtered water passes through any ‘downstream’ equipment like heaters or sanitizers and returns to your pool. If your pipes are smaller, it will force the water to move faster.

So, there are flow meters optimized for different size pipes. There are also models specified for the orientation of the pipes you are mounting them to. If your pipe run is vertical, you need a sensor that works vertically, same for a horizontal run.

Types of Flow Meters

Flow meters also come in three different varieties: analog, digital, or inline/integrated.

Analog

The analog variety is the simplest and usually the easiest to install. You will need to drill a small hole in the top of your plumbing. Your meter will fasten over the hole with a saddle or clamp, and its float valve will pressurize from the force of the water going through the system.

By looking at the gauge’s indicator, you will see a translation of that pressure shown as your flow rate.

An analog flow meter looks sort of like an old mercury thermometer. They are relatively inexpensive, usually costing well under a hundred bucks for models up to 2″ pipe diameter. Here is an example of a good analog pool flow meter from Blue-White. This model is for 2″ pipes, so make sure to choose a different option that fits your setup. Flow Vis also makes good analog meters.

If you have a huge pool, you may have pipes of a larger diameter. Still, even a 4″ flow meter isn’t much more expensive. Most DIYers can install one pretty easily.

Digital

Digital flow meters operate similarly to an analog model. They tend to be much more accurate than their analog counterparts, and they aren’t that much more expensive. But, they are sort of rare for consumer applications. Blue-White also makes good digital flow meters.

They also require power, so you will need electrical access, and some will need to be hardwired into your system, especially if they interact with your chemical feeders.

Inline or Integrated

Integrated or inline flow meters are actually a section of pipe with a flow meter installed inside of it. A typical model features an inlet and outlet with bulb-shaped housing in between them.

You chop out a section of pipe and install this flow meter in the gap using PVC glue and perhaps some new PVC pipe. The flow meter gauge will tell you the flow rate of the water traveling through the flow meter.

How to Read a Pool Flow Meter

Reading a pool flow meter is usually just a matter of glancing at the gauge or display. Some very high-end systems might have a remote display that you can remote from a panel inside your home or even on your smartphone or computer. But those are still pretty rare.

You will likely just need to go to where the flow meter is installed and look at what it says. A digital meter will show you a number.

The much more common inline or analog models have a simple gauge with an indicator bar that shows the flow rate of your water, usually in gallons per minute. Most swimming pools should be in the thirty to forty-five GPM range, but it varies by design.

How to Install a Pool Flow Meter

The exact steps for installation vary by the type of sensor you are installing.

In the case of an analog flow meter, you’ll be drilling a hole into your pipe. The size of the hole will have to match the insert on the end of the meter closely, so follow the directions and use the right-sized bit for your drill. Then there will likely be a clamp that holds the flow meter in place.

An electric flow meter is more likely to require a threaded installation. So, you will again have to drill a hole following the manufacturer’s specifications.

An inline flow meter is something most DIYers can also handle installing, though it certainly seems much more intense. You’re going to have to cut out a section of pipe large enough to accommodate the install.

Where many DIYers run into trouble is that they either cut out too small of a section and can’t fit the meter in, or they chop out too much pipe, and there isn’t enough play to glue it back into both ends of your new flow meter.

So, a better approach is to remove more pipe initially, and using additional slip fittings or unions, rebuild the run of pipe from one cut to the new flow meter and out the other side. This strategy gives you a lot more play to make your final connection.

Where Should Your Pool Flow Meter Be Located?

There are two big things to remember when installing a pool flow meter. The first is that it should be someplace easily accessible. If you need to take a reading, you don’t want to crawl on the floor or stand on your head. Locate it somewhere on the top of a pipe that you can see easily.

Second, make sure that the location of your meter is after your filter. If you install your flow meter in an area of the plumbing before the water is filtered, it can become clogged with debris making it inoperable.

How to Troubleshoot a Pool Flow Meter

The most likely cause of a problem with a flow meter is that it became clogged with debris or stuck in one position. To remove a clog, you need to access the flow meter.

An inline model will have a series of screws that hold the lid on. Simply remove the screws, and inspect the float, or flapper, and housing for any debris.

Make sure that the float moves freely. If this is a brand new install, make sure that you installed the meter in the right direction. There is usually an arrow to indicate which way the water needs to move through the flow meter.

An analog or digital flow meter will need to be unscrewed or twisted out of the pipe for inspection and cleaning. Remove the clamp, pop it out of the pipe, and look for debris clogging the float.

A digital flow meter might have a filter screen, as you might find on a washing machine hose. Make sure that screen is clean as well.

Sometimes, your equipment can also be affected by buildup, scale, or mineral deposits from your pool water. The best way to prevent this is to make sure that your pool water is always well balanced.

A swimming pool can sometimes feel like a big, open-air chemistry experiment. But by keeping your pH, total calcium hardness, and total alkalinity in the appropriate range, you can minimize the risk of buildup from the dissolved solids in your pool water affecting your equipment.

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Bottom Line

A pool flow meter is a good tool for a swimming pool owner. By monitoring it, you can remain alert to issues that might be affecting your swimming pool’s circulation.

For instance, if you think the water moves more slowly than usual, you might assume your filter is dirty. So, you backwash or clean the grids and guess that everything is OK. But, with a flow meter installed, you don’t have to guess.

You will see if cleaning the filter media fixed your flow issue. If your flow rate doesn’t return to normal, you can take the following steps: check your pump’s hair and lint basket for debris, make sure there isn’t any obstruction in your skimmers, double-check your valve positions, et cetera.

If you have a multi-speed pump, a flow meter can also help you fine-tune the operation of your system to save energy and save you money. And with the price of chlorine sky-rocketing, we need every bit of savings we can get!

Have questions? Drop me a message and I’ll be happy to help.

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