Ok so I set my tank up 7 days ago. its a 100L freshwater tropical with heater, top filter with the carbon/bioballs/ceramic rings. It has painted gravel, 3 plastic ornaments and an airstone and 3 live plants. Ive got two fish in there.
My ammonia, nitrites & nitrates are all 0.
My pH though is 8.0.
my tapwater pH is 7.0.
My water hardness (i looked it up on the water supplier website) is 16 mg/L which i believe is soft.
So any reasons why my pH is high? I was told it could be from the type of gravel as painted gravel is often cheap quartz and that raises pH.
My local aquarium said to add 30% change with rain water (only once off and not to keep changing with rain water): it lowered my ph to 7.4.
But why is there such a difference between tap water and my tank and what should I do? change the gravel?