you can tell if your main drain is working by perhaps putting a leaf on it. If it sticks, its working. In any case though, the main drain is not why your pool is having a problem. It has nothing to do with your pool turning green.
Swimming pool main drains don't actually drain anything. Rather, a swimming pool's main drain, if it has one, is a suction device. A pump is located underneath or near a swimming pool equipped with a main drain and it's used to pull water down into the drain.
For proper water circulation, it is best to position the flap so that it is about 2/3 closed. This will allow for more flow through the main drain than through the skimmer, which will promote a "bottom-to-top" circulation throughout the pool.
Turn on the water supply to the hose where the drain king is attacked and allow it to run for a couple of minutes. Stand back and watch the debris get blown back into the pool. Once the water runs clear, you can shut off the water to the hose and your clog should be all gone. Reattach the main drain cover.
During normal operation, water flows to the filtering system through two or more main drains at the bottom of the pool and multiple skimmer drains around the top of the pool. The main drains are usually located on the lowest point in the pool, so the entire pool surface slants toward them.
Many pools do not have them. They are not required. They might add slightly improved circulation and can be helpful for removing debris, but there are ways to counter these without the floor drain.
When constructing a new swimming pool, if you are going to use a main drain it is required that you use two. This is due to safety regulations to help prevent Main Trap Entrapment. Main drain entrapment occurs when the suction is so great through a single main drain that a person can become stuck on or in the drain.
A pool's main drain can become clogged with debris. Your swimming pool's main drain requires regular maintenance. Although the rest of the pool's parts, such as the filter, may seem to be working just fine, the drain is always at risk of getting clogged.
Put your hand over the inlet (where the basket is located on the side of the pool, not the pump) to feel if there's enough suction. Your hand should be sucked up against the inlet fairly quickly if the pump is set to its highest mode. If it's barely pulling, you likely have a clogged filter or a leak in the line.
Also, do not try using a plumber's "snake." A snake typically doesn't work on pool pipes because pools use 90-degree elbows and house plumbing uses 90-degree "sweeps," which allow the snake to round the corners. Also, a sewer-line snake should not be used on a pool for sanitary reasons.
So, if you see that you pressure quickly drops to 2 psi, it's likely that there's a leak in the main drain line somewhere between 4′ – 5′ under the water level of the pool. If there is a leak in the section of the line at or above the water level of the pool, you'll see a quick drop to 0 psi.
A diverter valve is typically installed in the bottom of the skimmer box below the strainer basket. A pointer on one side of the valve indicates the setting. Rotating the valve so the pointer is directed toward the pool diverts all suction force away from the skimmer to the main drain.
Or, as was the case in this wading pool incident, an open drain can suction organs out of the body. In 1993, Valerie Lakey, 5, was playing in a wading pool at a recreation club in North Carolina when she became caught in the uncovered drain's vortex. The pull was so strong that she was disemboweled.
Swimming pool builders often install overflow drains near the rim of the pool that prevent flooding most of the time. If you don't have an overflow drain, or if it is clogged, it is possible for periods of unusually heavy rain to overflow your pool.
There are ways to tell if the swimming pool filter is bad. If the water turns cloudy, then you know that your filter is not functioning properly. Leaking multi-port valves, broken or bad laterals, valve failure, tank failure, and pressure issues are some of the other indicators that the pool filter is bad.
If water is slowly coming into your pool pump, check the skimmer door to make sure it isn't stuck. Also, make sure your pool's water level is halfway up the skimmer. If the skimmer door and water level look good, you may have a clog in your skimmer line.
A dirty filter can clog, causing a sudden spike in the water pressure. The pressure can also spike if the filter is under more strain. The filter is strained when it's damaged, or the water quality has become too low for it to work effectively.
For testing only the main drain pipe for instance, cut the main drain and skimmer pipes (all of them), so you can move the suction manifold pipes out of the way. Then push on a SlipXFPT female adapter onto the cut pipe(s), and screw your pressure testing stick into the FTA fitting.
The main drain is the primary way that water is drawn from your pool into the pump and filter. The main drain is located on the bottom of the pool in the deepest part. Most pools have one, but larger pools may have multiple main drains.
Most pools have two main drains, but a small pool may have only one. The drains are positioned at the pool's deepest point.
To be safe a pool drain must not be “blockable.” This means one person should not be able to completely block the drain. One way to fix this issue is by installing at least two drains 36″ or more apart.
The two drains must be located between 3 feet and 6 feet apart measured from the centerline of the drain covers. The main drain piping must be manifolded at the hydraulic center.