Fertilizer is a chemical. Too much of just about any chemical can be hard on a tender plant.
The common miscreant is nitrogen. Nitrogen is expressed in fertilizers, particularly chemical based fertilizers (as contrasted with compost), as ammonia. Ammonia is very harsh on anything that is uptaking oxygen, like roots.
I have never seen a phosphorous burn, but its probably possible.
The most common way that fertilizer will burn a plant is by nitrogen burning the tender parts that are exposed to it. In land based gardens, that would be the roots. In water based gardens, that would be anything exposed to the water.
What I have seen is that the leaves curl, and the curled edges die, crinkle, and wither. This is the same for both land based and water based gardens.
In extreme cases, you can actually see the fertilizer deposited on the leaves of water lilies as a salt.
