In my 58 litre/12 gallon, tank, I have 1 young Shubunkin Goldfish. He seems fine, but when I test the water, the PH is 8. Is this too high? Ammonia and Nitrite are 0, Nitrate are 10. I use the Freshwater Master Test Kit, not Dip-Sticks which I know can be unreliable. I have 3 plants, some...