Are you growing this as a houseplant, or outdoors?
I personally do not use diluted fertilizer on the anthuriums I have in the ground, or the ones in pots hanging in the greenhouse. I used to use full strentgh Miracle Grow, which is 15-30-15.

However, in recent times, (ie this season) I have strayed away from MG and am using a special order fertilizer called Peter's Excel 15-5-15 Cal/Mag.

Why, you ask? Because the soil here (ahem I mean the SAND here) is so darn nutrient deficient, I found that some of my anthuriums (and palms and other plants) in the ground were having micronutrient deficiencies and MG wasn't correcting it. Rather than having to use a separate micronutrient spray or powder application, I use this fertilizer which is a water soluble just like MG but also has more of what my plants need.

I do have 3 anthuriums in the house as houseplants, and on them I use the same type of fertilizer, only once a month instead of every 7 days.

I personally don't think anthuriums are fragile plants. Mine are pretty tough, I grow many different species as well as the hybrids of "flamingo flower" type anthuriums. The more important thing to be thinking about than fertilizer is humidity, warmth, and correct light.

Anthuriums are mostly epiphytic in nature and the roots will always want to get out of the pot eventually. Good air circulation is key in the house.