Coconut spawning caves

[CatBrat]

Hi,
At the the moment I am keeping 5 Bristle-nosed plecos (2 males and 3 females) which I hope to start breeding. Recently while looking around home I came across some old coconut shells with large holes drilled into them. We had used them as homes for rats about 7 or 8 years ago. They are still very solid and in very good conditinon.
I was wondering if these would make good spawning caves and is there any special I need to do about cleaning them befor use?
Any advice would be a great help.

Cheers CatBrat.

[brett_fishman]

boil them.
or
bake them.