$5!! Could have been cheaper had I bought 'by the foot' instead of a 10' roll!!
the hose is 1/2"ID and 5/8"OD clear hose and then two 1/2" 90 degree bends and one 1/2" plug fitting. I took a razor blade and pinched the hose and cut tiny wedges out to create the holes. Difficuly level of this DIY is probably about 2/10 if that. I used a hairdryer to heat the hose while lying it flat to get it mostly straight since it had been in a roll at the store. The flow is alot better and the deadspots I had collecting crud in my little caves have disappeared now that the lower horizontal section flows right through the caves from the back to the front.
I was going to cut a notch in the wall of chamber 4 but didn't have to because the lid still closes normally with the hose going over the top and into the display.