Installing AGP below concrete slab indoors


In The Industry
Aug 17, 2020
Hello Pool geniuses. I am looking to install an above ground pool below grade in a warehouse type building. 30 x 60 Pool. 48 inches deep. Will cut through the slab and insert pool in the donut hole.

Thinking about the ground beneath the pool. Should I put in a concrete base and cover with a liner of some sort? If so, what should I be thinking about? Or should I just user a dirt base with a plastic liner to catch any overflow. I don't want a muddy mess. In either case, I anticipate using a sump pump to remove excess water. I think the walls of the cavity will have to be concreted in.

What should I think about for pump and pipes. It may be difficult to "tunnel under the slab in order to run piping. Is it worth cutting a trench in slab to run piping? Not sure exactly how much diameter pipe I will need. Pool volume is about 54k gallons. I suspect I might have to have dual pump/filters..

The AGP I looked at has support framing that extends 18" from liner. I anticipate the need to periodically inspect and monitor the outside of the liner..

Or is all this a silly idea? Is there a better way to build the hole, use the much less expensive pool liner and avoid these engineering headaches?

Obviously I am looking for the best solution in order to minimize the capital outlay. One day maybe I will go gunite and move ahead, but capital is tight right now.

Thanks for the ideas.


Mod Squad
TFP Expert
LifeTime Supporter
Jul 10, 2009
Houston, Texas
Hi, welcome to TFP! I'm not quite sure I can picture what you are going for. I would use plain sand under the pool, with gravel around the pool wall. You don't want anything that will catch and hold water next to the pool wall. You want any splash out to be able to soak into the ground so the pool doesn't rust from constant moisture exposure. Your pool should do fine with one pump and filter. A two speed, 1.5 -2 hp pump would suit your needs. You run it on low for everyday filtering, and on high to vacuum and mix in chemicals. Water filters best at low speeds. As for filter size, we recommend the largest you can comfortably afford. The larger the filter, the less often you clean it. Since you are building indoors, a cartridge filter would waste the least water for cleaning. I don't see any advantage to trenching in the pipes vs just running them on top of the slab, other than the aesthetic.
Which pool are you installing?