has anyone tried or used Hydra Crystals for algae in pond
Use the money you would spend on repeat applications of water treatments and invest in a UV light.
Save the money on both and solve the problem of excess nutrients.
I'm going to assume that since the pond gets algae blooms after storms, it takes run off that flushes nutrients in, thus creating the nutrient overload.
Rain water is supposedly "pure" but it is mostly not. Raindrops form around tiny bits of dirt and dust and whatever else the wind picked up, and that comes down too. Storms can carry all sorts of debris with it. That includes the fertilizer someone spread on their lawns and fields.