<p>Carlo,<br>
I also do c-41 at home, but I have a very different set-up. I have a thermostatically controlled water bath, with a pump to swirl the water around the bottles and stainless developing tank. The thermostat holds the temperature between 38 and 39 C. I use inversion agitation every 30 seconds and return the tank to the water. I am using Unicolor powder chemicals, and have used Arista and Rollei with no apparent difference. I start development at 3 1/2 minutes for the first roll, and add 5 seconds for each successive roll. I have no trouble getting 12 rolls per liter with consistent results. The benefit of inversion agitation and heat conductivity of the stainless tank may be the most important factors. Good luck.</p>
<p>Best regards,<br>
Chris</p>