Stewie,

There are battery operated air pumps for aquariums (aquaria?). Might be good to check them out (link below). They're not very expensive, however, you'll have to spend for the battery on a regular basis.

Ed

Here is a link that might be useful: Air Pumps

If you go to this website www.futuregardens.com they sell a valve, call (smartvalve) that works off off gravity.There no eletricity involve.

Check out link below.

Here is a link that might be useful: {{gwi:1003994}}

Smartvalve looks good. Would this stop the roots drowning? Only problem is im in scotland, so buying from the states could be a problem.

well stewie, if you arent in the usa you can always take this info to your local vendors for similar items. or buy it over the internet since its obvious you already have some type of access.

im doing NFT on my roof. its a 30 degree pitch.

there are units available now with solar battery chargers built in. can run both an air pump & water pump with them. c-p