irrigating a pyramid planter

I doubtless foolishly bought a pyramid planter for strawberries a couple of years ago. And of course the problem is that I can't water whatever is in it properly. I was thinking about cutting the top off and inserting some sort of piping down the centre to better enable me to water it, but not sure what to use. Should I used a hard pipe with holes in it, or a soaking hose? I was hoping to avoid emptying it (it took me several hours to fill it) but not sure if I can get round this. 
I am attaching a picture of what I think it looked like before filled (not surprisingly no longer on sale.) and one of just after I filled it.