Easier to just empty, dry out, coat the bottom/reinforce seams then let cure then test fill again. There's no applying pressure to the bottom to see if it changes flow.
Working on draining rest of water below the bulkheads out now.
Hello Pete, too bad, but only a small leak. Keep it going.
For draining the rest out, I'd take out the cap of a bottom drain, stick a 1 inch hose through, make sure it stays at the bottom (maybe with 2 stones taped to it) and syphon it out.