ehh.. 1/2" is pretty small. Probably will still work if you only have 25 sites but you will probably have to run your pump for like 8-12 minutes.I just built a 20 foot row for 25 sites using 1/2" tubing to 1/4" tubing. I haven't hooked it up to the 1500 gph pump yet, but i'm wondering if it is even going to work. I know I should have used 3/4", but will this setup work for now? I don't want to redo everything.