| Is there a big difference between filters for | | | | correct amount of water through the system to |
| aboveground pools and inground pools? They both | | | | adequately filter the water. It's not all about |
| filter water right? Besides, the manufacturer's | | | | Horsepower. In fact, most pool systems operate |
| specifications tell me that this filter can filter a | | | | with too much horsepower! And that's a waste of |
| swimming pool up to 20,000 gallons. So why | | | | energy and money. Think of it this way: all pipes |
| should I have to pay more than double the price? | | | | or hoses (depending on their size or diameter) can |
| The short answer is yes, but let's not be penny | | | | only handle a certain amount of water flow - let's |
| wise and pound foolish. | | | | say it's 100 gallons per minute (gpm) for example. |
| Those are typical, reasonable questions that many | | | | You or pool guy decide that a new pump is |
| pool owners ask. Let's look at some of the major | | | | needed. "Let's use something a little bigger that will |
| differences between filters for aboveground pools | | | | give you 'better' suction," he says. Now a pump is |
| and inground pools. But first we'll look at the | | | | installed that pumps 125 gpm - great! Not so fast! |
| similarities. | | | | Your pipes can only handle 100 gpm. Do you have |
| The similarities between inground and | | | | better suction? Maybe. Are you using more |
| aboveground pool filters are pretty simple. The | | | | energy to run the larger pump? Definitely. Roughly |
| first similarity is that there are 3 types of pool | | | | 25% more energy. Not only that, but the filter |
| filters - Sand, Diatomaceous Earth (DE), and | | | | doesn't seem to filter as well as before. That's |
| Cartridge. The second similarity is that they work | | | | because the water is being pushed too quickly |
| essentially the same - a pump draws water from | | | | through the media (especially true of sand filters) |
| the pool through the skimmer, then the water is | | | | - the filter system has to run longer because the |
| pumped through the filter tank and its media | | | | dirt can't be as easily trapped. |
| (sand, DE or cartridge) and returns to the | | | | But that's just one part of the flow discussion. |
| swimming pool clean and filtered. | | | | The other part is something called "head." Head is |
| The differences deal with pool plumbing or piping, | | | | how high the pump has to pull or push water up. |
| necessary flow and finally size. Let's discuss them | | | | Most inground pools have their filters above the |
| in order. | | | | water level. Sometimes within a foot or two (less |
| Pool Plumbing. The biggest difference may seem | | | | than 1 meter). Sometimes, it can be 10 to 15 |
| like pool size and gallonage. But in reality, it's more | | | | feet. The pump has to draw all of that pool water |
| of a function of pool plumbing. Most aboveground | | | | 15 feet up to the filter. Think of this way: is it |
| pools have their filter system right next to the | | | | easier to hold a glass of water over your head |
| swimming pool. Plus, the filter and pump & | | | | and pour it into your mouth or to use a straw to |
| motor are generally located below the water level. | | | | sip (suction) it? Plus then there are solar heating |
| In other words, the filter system is usually on the | | | | panels (often installed on the roof of the house or |
| ground with the hose from the skimmer feeding | | | | pool shed) and fountains or other water features. |
| directly down into the pump and the filtered | | | | Size. Finally we come to size. Pool size. Filter size. |
| water returning up to the pool's return jet - | | | | It's all important. Can an aboveground filter |
| gravity feed. Most aboveground pools have no | | | | system filter 20,000 gallons of pool water? Yes. |
| more than 6 to 9 feet (about 2 to 3 meters) of | | | | But is an aboveground filter system able to |
| hose on each side - a total of 12 to 18 feet. | | | | properly push water through 100 plus feet of |
| Inground pools on the other hand can and do | | | | piping and create enough circulation in the pool to |
| have many more feet of piping and plumbing. On | | | | push water down 6 or 8 feet in depth and back |
| top of that, there are usually multiple skimmers or | | | | up again? Or how about doing all of that plus |
| other suction lines - sometimes working in | | | | getting the water 25 to 30 feet in various |
| tandem, sometimes not. Then there are multiple | | | | directions? Inground pumps are made to do all of |
| return fittings or "eyeballs" or jets. Here's an | | | | that pushing and pulling of water. Aboveground |
| example, my swimming pool (with only about | | | | pumps can't. |
| 16,000 gallons) has a skimmer, lower suction, and | | | | How about filter size? Inground pools typically |
| 2 return fittings. Each wall fitting has its own | | | | have 20,000 to 40,000 gallons of water. All of |
| pluming line. Even though the filter sits just 15 feet | | | | that water needs to be filtered 2 to 3 times daily |
| from the pool, let's look at how many feet of | | | | for best performance (see our ezine article on |
| pipe there are for each line. The skimmer and | | | | Proper Circulation: "Circulation - First Key to Good |
| lower suction are relatively close to each other, | | | | Pool Care" for more information). A larger filter is |
| so they each use about the same amount of | | | | needed for the larger volume of water. |
| piping - roughly 40 feet each line or a total of 80 | | | | As a necessary aside, larger aboveground pools ( |
| feet going into the pump. The return fittings are | | | | 27 ft round and larger, and 18 x 33 oval and |
| on opposite sides of the pool. One return line is | | | | larger ) should consider utilizing a properly sized |
| about 30 feet from the filter, the other is about | | | | inground filter system. After the first season, |
| 50 feet - another 80 feet. My pump & | | | | many large aboveground pools experience water |
| motor has to pull and push water a total of more | | | | quality problems due to inadequate filter systems. |
| than 160 feet or TEN times the distance of an | | | | Unfortunately, these pools are "hampered" by the |
| average aboveground pool. Plus we haven't | | | | problem of having only one skimmer and one |
| mentioned heater, valves, elbows and other | | | | return cut-out. Ask your local pool professional to |
| fittings used in inground pools. | | | | configure your system correctly. Will it cost more |
| Necessary Flow. Understanding flow is the "great | | | | initially? Yes, but you will be much more satisfied |
| mystery" of the pool industry. Very few people | | | | in years to come. |
| practice it well. Simply stated, FLOW is putting the | | | | |