So, it does work, but not exactly as I had thought.
I ended up implementing it with no hatches at all, and a 5x7 repeater attached to a gear assembly powering the pump stack. Also, 1/7 water unfreezes then refreezes to 1/7 water. You need at least 2/7 water as the seed to get it to multiply. Finally, I had it going down a short 1 tile wide pipe, through an angle, into a cistern 1 z level lower. After a while, the water dropped to 1/7 and the top ice layer had to be opened up again, and the water had to be reseeded to 2/7. However, the flow rate is rather impressive. It took me 3 windmills to power it.
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In summary, I was able to multiply water using the freeze/thaw cycle. This is how I did it.
Cross Section:
___
___*|~~~~
| %% |
|_%% |
|~|
There is one tile of "seed" water (
~), exposed to the air, and some non-flowing magma (
~) (I had 6/7).
The * is a gear attached to a
minecart repeater, and further down, 3 windmills. Make sure that the gear is over the walkable tile of the pump, so that the water doesn't flow on to the gear and freeze everything up.
The %% is a magma safe pump stack. The top pump should be built first. You need to build some of the machinery on top first, to hang the pump off of.
The pump stack/repeater combo sends pulses of magma under the water, melting it regularly, and allowing it to refreeze. and the water flows away down the hallway. The seed water (
~) must be at 2/7 in order for the water to multiply.
If the seed water drops to 1/7, you need to break open the newly formed ice floor on top, and pour some more water in.
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The following is an idea that may help prevent the water dropping to 1/7.
______
___*|~~~~_^|__
| %% | |~~ -> Cistern
|_%% |
|~|
The ^ is a pressure plate set to 6/7 water, and it is attached to a hatch cover -
_.
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edit: Just tested, and it works wonderfully. Flow rate is really good too. Not quite like piercing an aquifer or a river, but it's not too far off. It does reduce FPS somewhat, but I have no idea how to reduce that to a meaningful number.
If you want to see it in action, save is at
http://dffd.wimbli.com/file.php?id=6936 I have no idea on the status of the fortress, as I mostly just ignored the dwarves. It does use a tileset. I had invaders off and pop cap set to 30. And it is modded a bit, but the mods aren't really relevant, and shouldn't be noticable.