Looks like the Settling Tank is ok...found that the bottom had quite some space below, so I washed in 3 bags of sand to support.
Filled up all rivets and another ring at the bottom-drain with silicone, waited a couple of hours and started to fill first a bit, then step by step until now. I'm at 60%, just above the connection of the two antenna.
So now we will wait, at least there's no water leaking at the connection anymore, and filling seems to have been much faster than before, another show that most leaks are now plugged.
Will hope for Monday to have not much loss of water. Mr.T. is doing fine, but I'm very anxious getting him over. Too hot and windy for his current small pond.
With luck, we're able to make his pond smaller next week, roll out the liner and fix the bottom-drain.
Let that dry, then start filling for testing the bottom-drain and settling-tank.
If ok, then we'll start preparing to move Mr.T.
Took the Bottom-drain Dome out of the mold. Bit of work to smooth it, then paint it and ready to go on.
Hole is just big enough for male PVC adaptor for the air-diffuser. So it will be a matter of measuring the exact hight, then glue the diffuser and adaptor. Add tape and then stick through the dome, screw it in the drain-adaptor...finished.