What deficiencies are you seeing from the photos?
A Mobile Nutrient deficiency which can be caused by any one or more of the following nutrients:
Nitrogen (N)
Potassium (P)
Phosphorous(Phosphate (P)
Magnesium (Mg)
Chlorine (CL)
Molybdenum (Mo)
visually it can be very difficult to isolate just one nutrient. But with 50 fish NPK seems unlikely. And since tap water is treated with chlorine, a CL deficiency seems unlikely. That leaves Mg and Mo. But Mo is typically only needed in very small quantities 0.001 PPM while Mg is needed are at a minimum 1.0 PPM. So Magnesium is the most likely mobile nutrient in my opinion.
How much water do you change out during the water change and how many gallons is in the tank? it is highly unlikely that water evaporation is entirely the cause of your high GH reading. I do a 50% water change once a week. Anything less than that can result in an increase in hardness.
According to your utility water quality report your tap water likely has about 4PPM Mg, 22 PPM Ca, Cu well above what is needed, with no Zinc, Boron, and molybdenum, detected. So in my opinion Magnesium, Zinc and Boron and Molybdenum are the most likely ones deficient in your tank.due to your low fertilizer and tap water levels. Iron and Manganese were also not detected but your fertilizer is not deficient in those two.
Note there is a lab water test that can be done on your tank and TAP water. It is call and
ICP-OES water tiest . It costs $30 per test. and you get results in within one week of mailing in your water sample. It will detect every nutrient I have mentioned down to 0.001 PPM. Except it won't detect Mn (dose to iron interference) and it also might not read Cl correctly. It can eliminate guessing the cause of the deficiency. This test is a popular tool for salt water tanks and much of the advice is salt water focused. For tresh water ignor their advice and just look at the numerical results.
Where are you getting all the minerals to add to your tank? It's safe to add Epsom salt to my tank?
On line. I can get most in small quantities at 99% purity levels though
LoudWolf.com. You can find all at Amazon.com but often the smallest size available is typically 1 pound. And
Nilocg.com has a limited but useful selection.
It's safe to add Epsom salt to my tank?
I have used all the ingredients I have listed in my tank including Epsom salt (99% purity). Preferably you want pure products that don't have any coloring, dies, or potentially toxic additives. And you can used the
Fertilizer calculator I mentioned earlier to calculate how much to add to your tank to reach a target level.