In regard to the first post:
It's also a good Idea to run a smal air pump with an air stone at night. Plants will actually use Oxygen at night when there is no light, and CO2 in the day when there is light. When I get my CO2 setup it will be as such.
I just got a sweet timer from the LFS. They had two models. One had a timer on each end and an inverse swtich for each timer. Meaning that for each timer you had a "yellow" zone and a "green" zone. when the green zone turned on, the yellow turned off and visa versa. I got the cheaper model with just one timer and two outlets for a green zone and two outlets for a yellow zone as well as four always on outlets. Here is a picture:
I have his little brother:
As for the Solinoid switch I got a brand new one off of Ebay for $5 plus shipping. There are two kinds, "normally closed" or "normally open". Pic your poison I guess.
Here is supposed to be a good supplier
ASCO Valve - 2-Way
On a side note.... I have been looking at computer controlled timming schemes using x10 technology
though it seems to be down right now, weird). These badboys can be turned on/off and dimmed all using software on your computer. There are two different software packages I've been looking at, one Windows Based(http://www.draquarium.com/)
one Linux Based ( http://misterhouse.sourceforge.net/)
I installed DrAquarium and it's setup to do a simple water change and chemicals check reminder via Email, but this little gem is supposed to let you control everything from sunrise/sunset and moonrise/moonset times to Emailing you when your pH gets to high. the built in x10 plugin lets you control anything you plug into the wall. I can't wait to get my CO2 setup so I can program it to come on/off along with my lights.