Are there any fleamarkets soon in Brussels?

We have a lot of stuff, clothes, kitchen equipment, decoration... that we do not need anymore but is still in good shape. I can't be bothered to take pictures of everything and sell it online therefore I would like to sell it during a fleamarket. Can you recommend any fleamarket that is happening during summer where private persons can sell?
Do you have any experiences with these?

Thanks a lot in advance