Swimming pool Q&A.(The Orlando Sentinel)

Q. I am having a pool built and noticed that there are two round brackets in the floor of the pool. My neighbor told me they are main drains. His pool, built three years ago, has only one main drain. Is this a new innovation?

A. No, your licensed pool builder is up on industry technology. Several isolated incidents in commercial and residential pools and spas highlighted the need for design modifications of the drain. Individuals had hair and other body parts trapped in the drain because of broken or missing drain covers.

Recent safety innovations have allowed the pool industry to offer products with dual intake ports and in your case, main drains. These devices remove the dirty water from the bottom of the pool and take it to the filter for sanitizing. The clean water is then sent back through return lines. Two ports lessen the suction power of the intake circulation/filtration system, without diminishing overall intake water pressure.

In years past, the cover of a single pool or spa drain was in a grate or domed, slotted design. This design would allow the full force of the water going into the main drain to create a tornadolike vortex. 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 ...