Considering the test results, most likely, photosynthesis can be ruled out as a cause for the high pH. That does not infer excess lime is the issue, it just means, most likely, photosynthesis is not the cause.
Ammonia exists in two states, depending upon pH and temperature of the water, ionized ammonium (NH4), or un-ionized ammonia (NH3). I am not sure of your temperature but your pH isn't dangerously high, independent of temperature.
It may be wise to limit your feeding until you do have a good rain, just to keep ammonia levels low and there is a drop in pH.
https://www.patroutintheclassroom.org/docs/default-source/resources/how-to-calculate-your-unionized-ammonia-levels1-(2).pdf?sfvrsn=ba831777_2
