I’ve been using this gravel Pisces Midnight Pearl Aquarium Gravel https://www.amazon.com/dp/B075NWC8TP/ref=cm_sw_r_cp_api_glt_fabc_0QBGFW5ZHSJ86ADKAQXR?psc=1 And it works great, good if you want a grey+brown toned natural look. They are also pretty easy to clean, no color getting off when rinsed, I just rinsed them two or three times and they were clean to go.