skimmers and main drains

[doc]

I am having a 18x36 vinyl pool installed and the company never uses main drains. I am curious to know if I should request one be put in? Also, how many skimmers are needed for a pool this size? thanks

[Me...]

I know some people leave them out as a cost savings and others are hell bent against them as being unsafe. Unsafe is idiotic installations, drains with no covers or massive flow through a single drain. If you install dual drains and have separate main drain and skimmer lines run back to your equipment room you will have a MUCH better system.

[finny]

Thank you for the reply. How many skimmers should there be , two? or is one enough?

[Me...]

Generally it is recommended to use 1 for every 400 sq.ft. of surface area, so your pool theoretically could use 2. You also have to take into consideration the surrounding area and how much debris will blow into the pool. Again there is a flow that will need to be pulled through them so a pool with low flow will not work 2 skimmers very well while keeping some flow through the main drains.

Your pool could be around 25,000 gallons if it has a deep end. 2 skimmers and 2 main drains would want something like a good solid 60 gpm so I would be looking at a 30" sand filter and a GOOD 3/4hp pump. Something like a Pentair Whisperflow. Vinyl pools would be more difficult to use floor fittings in so 3 well placed wall inlets would do nice, possibly 4, and plumb it all in 2" pipe. You could also look at a 2-speed pump to use low most of the time, high speed when needed.

That would be an excellent pool however 1 skimmer, 2 drains, 24" filter and 1/2hp pump might still be ok but I would still use 2" plumbing.