More Fountain news - Gotta love physics!

[GoneOffShore]

So, I've been constructing a fountain in my back garden with the help of my neighbor and had reached an obstacle: The concrete base was poured, most of the wooden forms had been removed, but there was a problem. When we constructed the forms we were in a bit of a hurry and neglected to provide for a way to get the piece of plywood on the bottom of the fountain pool out. The side forms were easy - undo the screws holding the braces and pry them away with a crowbar.
So, there I was with a beautifully square concrete basin with a piece of plywood submerged under two inches of water and no way to get it out. I first tried the crowbar - not the best idea as there was no real place to rest it and pry up the plywood. Also there was the suction factor as I had agitated the concrete to insure a beautiful flat base. There was also the copper pipe which was inserted into the concrete to accommodate the tubing carrying the water up to the fountain outlet.
I drilled a couple of large diameter holes in the plywood and burned out a drill bit doing it. Then I inserted the crowbar. Nothing budged.
Okay, change the plan. Lag screws. Large diameter lag screws! Bought them, screwed them in and then we had five days of rain. The plywood and the bits of wood at the bottom of the basin absorbed the water and swelled accordingly. And my plan to put eye bolts into the plywood and have some friends lift the plywood out with nylon ropes fell by the wayside.
Today I decided to remove the plywood. Of course, because of the rain we've had the basin now held about eight gallons of water. I hooked up the new pump and got a lot of the water out. Then, using the magic of physics, I partially refilled the basin with a garden hose, left the end submerged in the pool, turned off the water and unscrewed the hose from the tap. I then dropped the hose into the yard drain using the hose to siphon off the remainder of the water in the basin. It worked beautifully.
Then there was the problem of the plywood in the bottom of the basin. I took the lag bolts and screwed them into the plywood. I kept turning one of them and suddenly there was the sound of the air being sucked into the space between the plywood and the concrete. The plywood lifted, slightly. I moved to one of the other screws and screwed it down into the wood. More sucking noises and the plywood lifted further. The third screw was turned into the form and at last it lifted the plywood away from the concrete!
Now I have to wait for the concrete to finish curing and I can set the granite tiles into the basin.
We'll have a fountain very soon.

[Kingshakabobo]

1. When I read your original thread I wondered if you used a release agent.....

......to make separation easier. The concrete was already poured so I didn't bother. We used to spray diesel fuel on the forms to facilitate easy release.