inward bulging of side walls on rectagular metal frame pool

Hi,

I have recently set up an Intex 10' x20' rectangular metal frame pool with a vinyl liner on my backyard, (concrete surface) and started pooring water into it, I am almost half way and have noticed that the side walls (20') are starting to curve towards the inside of the pool so I stopped filling more water into it. I am wondering if this is normal or if this means that the concrete surface is not really leveled, which I think is the case, I am assuming the raining water needs to flow somewhere.

Should I be concerned or would you say once the water reaches the required level, it will realing the side wall frame.

Thanks

Sacto

The only large metal fram pools I'm familiar with are the Intex ones used for dock diving competitions. On those, the sides bulge outward and the posts sort of curve inward. These pools don't have solid sides though, just posts.

my old intex kinda got a small waterdrop effect while filling- the bottom edges pushed out as water built up in the pool, making the top diameter slightly smaller than the bottom- if this is what you're talking about, it's normal
Make sure the posts are straight, and the pool is not leaning one way or the other- all sides are sloping inward slightly from bottom to top, not all leaning left/right...