Why We Added a Belt Between White and Blue — Marvin Castelle & Coach Kay of 10th Planet Torrance, CA

This is a conversation about what it means to go from being a student in someone else's room to being the person who sets the culture, the pace, and the standards for your own. Professor Marvin talks honestly about the learning curve of gym ownership, how it humbled him in ways that jiu-jitsu competition never did, and why he thinks running a business is harder than anything he's faced on the mat. He describes the difference between making a game plan in jiu-jitsu, where it often works, and making one as a business owner, where it usually doesn't. Chapters: 00:00 From Fighting to MMA to 10th Planet Black Belt 11:13 Bay Area Striking to 10th Planet Torrance Ownership 23:01 The Humbling Journey of Running a Jiu-Jitsu Gym 35:43 Creating a Safe and Accountable Mat Culture 50:49 The Grey Belt 58:30 Balancing Technical Drills, Eco Training, and Grit 01:15:57 Cross-Training, Gym Loyalty, and Lifelong Grappling 01:35:38 How to train with Prof. Marvin & Coach Kay A significant part of the conversation focuses on teaching. Marvin explains how his own intensity, shaped by years of training at 10th Planet HQ under Eddie Bravo, had to be recalibrated once he was responsible for a room full of people with different goals, fitness levels, and emotional thresholds. He talks about losing students early on because the energy in the room was too high, and the specific adjustments he made to his voice, his class structure, and his expectations depending on whether he's teaching beginners, intermediate students, or his advanced competitors. He describes it in layers: beginners get calm and measured instruction, intermediate gets structure and accountability, and the advanced class gets a more militant pace. He's candid about the fact that this didn't come naturally. Coach Kay's story is its own thread. She started jiu-jitsu at eight years old, had to quit when the school closed, and came back as an adult through a winding path that included gymnastics, kickboxing, and a series of gyms across the Bay Area and Southern California. She talks about what it was like training as a woman in rooms that weren't designed for her, and how Marvin's decision to create a dedicated women's class at 10th Planet HQ gave a group of female practitioners something most of them had never experienced: consistent, competitive training with other women. That class ran for months and drew women from 10th Planet schools across Southern California. It changed the trajectory of several people's training, including her own. They also get into Marvin's decision to add a gray belt between white and blue in his ranking system. His reasoning is specific: too many white belts get promoted to blue before they have the tools to survive what blue belt demands, and the result is either injury or quitting. The gray belt gives students time to build a foundation in leg locks, escapes, and live training intensity before they're expected to hold their own against seasoned blue belts. He walks through how it works, what he expects at each stage, and why he believes his blue belts are stronger for having gone through it. The conversation also covers the ecological and constraints-led approach to teaching, how it intersects with 10th Planet's existing drill-based culture, and where Marvin sees its limits. He's open about what he thinks works, particularly for kids and for building movement quality, and where he thinks it falls short, especially when it comes to deep technical positions like leg lock configurations that are difficult to arrive at organically. He and Coach K both talk about how Eddie Bravo's classes at HQ used live drills and positional sparring long before the ecological framework had a name in the jiu-jitsu world. Throughout, both of them come back to the same tension: how do you build a gym that's tough enough to produce real skill and soft enough to keep people coming back. They don't pretend to have it solved. They're working on it in real time, with a young gym, a new baby, and a community they're still learning how to lead. — Train with them: 10th Planet Torrance — 10ptorrance.com Monday–Thursday and Saturday Instagram: @10thplanettorrance Professor Marvin: @marvincastel10p — Grappling Monthly is an independent editorial media brand covering the people, gyms, and stories behind Brazilian jiu-jitsu and the grappling arts. Subscribe: youtube.com/@grapplingmonthly Instagram: @grapplingmonthly Substack: grapplingmonthly.substack.com #bjj #jiu-jitsu #martialarts