Doesnt have to be huge, looking for a minimum flow rate of 4-5 liters per minute, capable of lifting water minimum of 2 meters (3 would be better), designed to run 24/7 and most importantly run off 12 volts. Preferably under £20. I've been searching online but only found one so far that comes anywhere near spec. Most of them are 240v, which is not an option.
My best mate's quite straightforward water pump (run off the mains) for his average sized outdoor pond containing a modest variety of fish, cost just into three figures - and he thought that was reasonable.
thats not an issue. Purpose is to run a water clock, hence the 24/7 nature. 12 volts for safety and someone else is looking at powering it via a battery and solar cell. I was given the ballpark figure of £20 as its being done on a shoestring, but I suspect the power source may be a bit costly. But thats not my department thankfully (I'm just designing and building the clock. If it works ok I may just post a picture. but dont hold your breath<g>). For reasons that are somewhat involved, 240 volts is simply not an option.
Just build one of these. It'll obviously pump enough flow, and the height looks fine. It might overshadow the water clock, but I am sure the result would be most impressive. No 240 volt problem, either.