Sorry about the dye color. There are some old threads about people dying their ponds. In my recollection, it took many of them a few "experiments" to get the dye tints and concentrations correct. Keep good notes, so you can replicate your treatment and schedule when you finally get it right.
Is your posted picture DURING your algal bloom? It doesn't look bad to my eye since I can see your rocks a fair distance below the surface of the water.
I don't see any reason to worry about accidentally fertilizing the pond, unless there is some unknown issue? Yes the algae took up your fertilizer more quickly than the rooted plants. However, when the algal bloom is over, the resulting organic remains will provide some fertilization effect to the rooted plants.
It may be that getting your lawn/ground cover established is your most important task. You do NOT want a big rain washing sediment into your nice pond.
I do like your pond contours and your rock edging!
P.S. Your water loss rates might not even be a leak at this point. A 1/4" loss over 3-4 days is probably pretty close to your evaporative losses. The greater losses at full pool might be due to a slight leak, but could be just due to your topsoil imbibing some water and your grass utilizing it.
