Ich benötige Ideen um dieTemperatur im Zelt zu senken

You can move the dehumidifier out of the tent and treat the air in the room where the tent pulls fresh air in from. This then allows the heat to dissipate a bit instead of being trapped into the tent. Also you should be running an extractor fan to take out the old air and bring in new air. With this setup it treats that main room where the tent is located like a lung room. This is how I grow. I work on the air going into the tent and then just adjust the extractor fan to pull more of it in faster or slower based on tent needs. 30c is not to bad on its own and if your RH is down to 50-60% then its fine. It will creep up even higher some days. its bound to happen, let it do what its going to do unless you have air condition in your room where its pulling air in from. its an added cost and not worth it just for the weed, but got your own enjoyment of the space yes and weed plants as a secondary if you can afford it.