pearling is always a good thing. as seattle aquarist said, pearling means there is increased photosynthesis, which means the plants are growing. the added doses are probably giving the plants what they need to do more growing. deficiencies would be more like holes in leaves, curled leaves, misformed leaves, plants not growing and/or dying, etc. think you're on the right track! but always be careful, what's loved by the plants may not always be loved by the fish/shrimp/etc in your tank. finding a good balance is key.