Help! Chemical Balances

[Aquaholic]

Hey everyone I need some help, I have a hagen KH/GH test kit and i was testing the GH. The test at the start is pink and then supposed to turn a yellow with a certain amount of drops, the problem is the solution goes from pink to purple never getting to a yellow/lime color.

All my other levels are:

Calcium: 450
amonia: 0
PH: 8.3
nitrites: good (cant remember exactly)
nitrates: 10 ppm
Magnesium: not tested
Alkaline: not tested
Phosphates: 0

All my fish (less one, box hasent recovered from getting stuck on filter, trying to save him) are doing well, i seem to be finding some hermits dead sometimes, bout 1 every 4-5 days(i think there is an over aggresive hermit in there). I also have 2 stars, sand and lactina, both fine.

I dont know what to think.

Help me, I'm weak and frustrated.

Thank you