Posted: 28/08/2014 at 18:15
Hi David. The walls of decent hosepipe are often reinforced and would, I think, be too tough to puncture neatly at the point where you insert the micro bore tubing (which then connects onto the drippers). You can get droppers which insert directly into the supply hose but these also rely on a tidy insert hole.
A ragged hole in the hosepipe would almost certainly leak - which would both waste water and reduce flow to the droppers. I, therefore, don't think your idea to recycle the old hosepipe would work very well - better to use the 13mm hose sold by Hozelock or Gardena. You can buy mini taps which you set into either the 13mm tubing to shut off a whole section of your irrigation system and I think you can also get mini, mini ones for the micro bore tubing so you can turn off individual bits of the micro tubing.
If you are going to go down the irrigation route it really is worth spending some time planning exactly how you want it to work so you get all the bits you need. You can change it once it's set up but it's easier to get it right from the start.
If you're going to go down the timer route I would also advise spending a bit more for one that gives you really flexible watering patterns. The cheapest will give you (say) 15 mins every day which is fine for containers. But I found that for irrigating beds and borders I was better off having the system running for longer (say 45 mins) but only every 3 days.