I am not sure who would have recommended that you always keep the soil of Anthurium clarinervium moist. That is the problem, its too much water.
In nature, Clainervium grows on Karst formation in only a very thin layer of poor soil, effectively as a lithophyte. It sends roots into he cracks in the rock formation, and when water from rain filters through, it takes up that water.
Adding lava rock, LECA, Pumice, Perlite and bark as amendments would be beneficial.
