Minimum distance between NO tubes

[gophia]

Is there a minimum distance that I have to respect between NO tubes in a canopy. I have a custome built hood that I currently have 4 NO (15W) tubes on a 15 gallon and was planning to add 1 maybe two more.

[Leopardshark]

i really don´t think there´s a minimum distance to be respected between each other. I had 4 NO´s in a canopy in an old tank and I had no problem placing them very close to each other.
Marco

[slipknottin]

Far enough apart that you can get enough leverage to turn the bulbs so you can remove them later.

[gophia]

Thanks for the replys. I was just worried that the heat produced from one bulb might affect the other bulb, i.e. over heat the other bulb and cause it to blow.