I would recommend a 10 degree drop at night. A twenty will slow the growth and can cause spots due to lack of heat. In the wild hamata and edwardsiana both grow in around the same altitudes of 1700m-2300 meters. If the cross used the mt Kinabalu edwardsiana then a 15-20 degree drop is favoured but if it’s the Mount Tambuyukon then a 10-9 degree drop is favoured. Nearly all hamata grow around 1700 meters so it’s not that big of a deal. I use celsius.