Okay, geremyh, this is what you're going to do. You're going to make 50 or so prototypes to test your product. 10 to be bisqued to a low cone. Say, cone 010. Then 10 bisqued to cone 06-04. Then 10 bisqued to cone 02. You're then going to make 10 with paper pulp in the clay, 10 with perlite.
For each 10 prototypes, you're going to test 3 in loam soil, 3 in sand, and 3 in heavy clay. Hook each prototype up to a plastic hose or pipe similar to your design and hook up that hose/pipe to container with measurement marks on it. Test the flow that way, with an average of the three of each type being your significant number. The final one of each will be for destruction testing for durability.
After this, repeat the experiment with your decorative glaze added. Maybe only the worthwhile ones to save money/time. The cone 010 will likely have to be excluded--you're going to have a tough time finding a cone 010 glaze.
I think as a courtesy to us, as we have freely offered up information to you, you should publish the results of your experiment here. No design details, just the results of your experiment which betrays nothing proprietary.
Then, I think you should apologize for misrepresenting yourself. In your initial post, you said you were a "super amateur" looking for help with "gifts." On your last posts, this is a business venture. If you're a business owner/CEO, dishonestly asking for free R&D isn't cool. If the reverse is true, and you're just an amateur, lying about your professional status to save face isn't cool either. I apologize for being a little stern, we're an honest group filled with goodwill here, dishonesty would kill the convivial spirit. I like the people here a lot.