Main drains are an essential component for water circulation within an inground swimming pool. Drains provide circulation in the deep end of the swimming pool, ensuring water clarity, proper distribution of water chemistry as well as maintaining a constant water temperature throughout the swimming pool.
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.
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.
Use small submersible electric pump and garden hose, or b). Start a siphon with your vacuum hose / head on the pole, or a siphon using garden hose(s). Pumping the water far from the pool's edge is best, so as not to oversaturate the soil supporting the pool. Monitor the draining and the discharge.
You need a main drain in your pool because that's where the hydrostatic relief valve will be installed. It is also the best way to achieve proper filtration and circulation of pool water.
The main drains are usually located on the lowest point in the pool, so the entire pool surface slants toward them. Most of the dirt and debris that sinks exits the pool through these drains.
Pools without main drains are becoming more popular since most cleaners can provide the ability to pick up debris at the bottom of the pool and circulate water at the same time. I still like to use main drains, especially with VS pumps because it allows a larger volume of water for the high speed end of these pumps.
Your water should only be drained so it sits just below the skimmer and jets. This helps make sure that no water can get into the pumping system. You may also need to drain a few extra inches of water, depending on the type of pool cover you're using.
If the level of groundwater is high (which, in some cases, can be all the time. In other cases, this could be only after heavy rainfall), the pressure can cause the pool to heave out of the ground. On average, a pool should be drained and refilled once every three to five years unless there is an emergency.
Splitting a Pool Drain for Safety
This means that the drain pipe is T'd off to two drain covers instead of a single drain. This practice is known to reduce the risk of serious injury or even a fatality, since if one drain is blocked (i.e. by a person's body), the other drain “takes over” releasing the blockage.
A main drain is responsible for aiding in the circulation and filtration of the pool water. Having a properly working and dedicated main drain line can also allow you to fully drain your pool if necessary. Main drains on older pools are often attached to the skimmer lines back to the equipment.
The use of two main drains allows the water flow to be diverted equally between two intake ports and suctioned through a new domed, slotted anti-vortex cover. In many cases the drains are also spaced several feet apart, lessening the intake flow.
Slowly close the Main Drain valve about halfway, this is the optimal setting for vacuuming. Make sure the skim-vac did not come loose over the skimmer basket and is sealed securely over the basket. Push the pole/vac/hose into the pool and release all the air out of the hose.
More suction may be needed at the skimmer than the main drain to effectively remove the floating debris from the surface. Therefore, you would want more of a skimmer opening than a main drain, about a 70/30 split – skimmer/main drain.
The two main drains must be at least 3' apart, but no more than 6' apart.
Timeframe – Never keep your pool drained for more than a day or two. This can cause the ground surrounding your pool's foundation to shift and change, which can cause extensive damage to your pool and the area around it.
The best time to drain the swimming pool
Too cold or too hot weather can seriously affect an empty pool and cause cracks in the liner. Most homeowners decide to do it in the spring so that the pool is ready for summer activities. It's also OK to do so in early autumn when temperatures are still mild.
Low water level
The most common reason why bubbles blow through the return jets is that the water level is too low.
The best way to prevent pool overflow, however, is to have a swimming pool overflow drainage system in place. Slot Drain Systems offer a pool overflow drainage system that is installed around the rim of the pool. This drainage system helps manage and prevent water overflows in and around pools.
With the pool system off, open your backwash valve (or drain line if you have one). Close off all skimmer lines with a plug or the valve(s) on the suction side of the pump. Ensure you'll be drawing water from only the main drain (if equipped). Turn on the pool pump to begin lowering the water level.