Kimchi Fermentation at exactly 18°C – Conclusion

I rigged up a small thermostat controller for the fridge to keep the fermentation consistently at 18°C instead of room temperature. After 72 hours, the acidity was noticeably mellower than in my previous attempts with fluctuating 20–24°C. The gochugaru came again from the Asian market in Neukölln, 45g per 1kg of napa cabbage, weighed precisely. Only problem: the jar bubbled over a bit, next time I'll use a bigger Weck jar with more headspace. Does anyone have experience if 18°C is generally recommended or rather lower for more crunch?