If you are on municipal water you can get the numbers from the water treatment plant, perhaps they are posted on their website, others have been. I have very hard water with 23dGH and 21dKH but find that it tends to go lower in the tank depending on a few factors. Witha 7.8 I would assume (but don't know) that your water is on the hard side... maybe over 10dGH (GH is more important to know that KH but the test kit that measures one also measures the other). I chose fish that had ranges that included those levels assuming that I cold lower it somewhat by using reverse osmosis water as necessary to cut the hardness.I am looking to get a few different fish for my 75g tank. They all can live within the same temp and ph. But, The Kh for these fish are at different levels. As my name suggests I am a fish noob. I have not tested for Kh ever. Will this stop me from integrating the fish I want?
Fish are as follows:
Roseline barb (denizen) kh 4-10 ph 6.5-7.8
Rainbow kh 9-19 ph 7-8
Cardinal tetra kh 2-6 ph 5.5-7.5
Rio **** L135 kh 6-10 ph 6.5-7.4
Singapore shrimp kh 3-10 ph 6.5-8
I have no idea about what kh are and what kh levels in my tank are. Living in Colorado my ph is naturally around 7.8.
To say that fish are adaptable is a pretty board statement that needs some clarification. The ranges that are given are ideal ranges for the fish and some tank raised generations of fish can tolerate wider ranges but tolerating and thriving are two different things. So it comes down to a personal decision as to which conditions that you prefer to keep fish in, tolerating or thriving... of course there is also a third option, just keeping them alive... but I don't think that one applies here.