Which paired test?


I have a little slightly complicated analysis which I want do describe
in form of another similar but clearer example:

I have 15 different stones (different material, different size). Each stone
can be identified (e.g. has a number).
Now I have an experiment where I through each stone into a tank filled
with 1. Water, 2. Saltwater and 3. Oil. from 1. 5 cm height and 2. 30 cm height.
I measure the time (t) each stone takes to sink in the different settings (liquids x height).

What statistical test do I need to analyse if the liquid and/or the height has any effect on t. Of course there is already variation in t due to the size of the stones but I am not interested in differences between the single stones.

I want to do my analyses with R. So is there anything like a paired ANOVA resp. is that a statistical tool for such analysis?