Rather than pollute and sidetrack Behjold's thread any more I have decided to start up a new thread here. Further to Simon's suggestion I've been looking at buying clear PVC pipe to make up a reactor and pricing things up a little further and I reckon I can do a reactor as the drawing below for about Â£25! That would include a half metre length of clear PVC, Grey PVC socket and bend at either end (they don't do the clear fittings in metric measurements!), 2 threaded reducers (to bring the 1.5" threaded sockets to 1/2" threaded) and 16mm or 12mm hosetails that fit into the 1/2" reducers, and a 16 or 12mm reducing tee with a 4mm connection for the CO2 line. I am quite happy to assemble them if people would like them but to get them at that price we'd have to have 10 people! Otherwise it will cost more per section. If people want a longer reactor then they could have that for a bit more. I could also change the design in any way people want to fit in with their ideas or send you the bits for you to make it up yourself. As I'm not going to charge for any labour though that won't make it cheaper!!!! This won't include postage so that may up the price a bit, but I can't imagine a hollow plastic reactor will cost much to send! I could also get some plastic Bioballs if people want them in the reactor, though I don't think I'll bother as I don't think they helped in my last reactor at all. Let me know on this thread guys if anyone would be interested. Once I know whether there's demand or not then I can look at whether it'll be viable.