LetterBee wrote:
Wifey has just bought a 10foot circular paddling.swimming pool. Its 36
inches deep but gets filled to 30inches. As you can imagine, thats a lot of
water.

Let's do the numbers, rather than imagining. 10ft = 3m, NADI. Call the
30ins 0.8m (NADI, again). Area of your circle is pi * 1.5 * 1.5 (that's
pi-rsquare, r being half of d), or 3.2 * 2.25 = 7sqm NADI. 7sqm * 0.8m
gives us 5.6 cubic metres, and (since a cubic metre of water weighs a
ton - or tonne, with the precision we're working to) that's between 5
and 6 tons of water.

Now, wood's pretty strong, especially in compression; but I wouldn't
want to support 5+ tons of fun on "four corner posts". Since you only
want to raise the decking a few measly inches, I'd be looking to
construct a base of tannalised (preservative-impregnated) timbers of the
right thickness - maybe sthg as crude and widely-available as 4x4
fenceposts would do? - resting either straight on the ground, or on
paving slabs bedded into a small depth of concrete, with a couple of
ground fixings to encourage the whole thing to stay in one place (not
that it's going to go far, when filled). As the attraction of an
unheated, uncovered, cracking-after-a-season-or-two paddling pool will
fade after a season or two, I wouldn't aim for a structure of great
permanance...