Also, if it is a brand new setup, you'll have to let the tank and the filtration system cycle. Meaning, the bacteria has to be established inside the tank as well as in the filters. This can take anywhere from 3 to 6 weeks or so to be safe, unless you use additives that make this process go faster. There are a few ways to properly cycle a new aquarium if you look online. I hope this helps.
I agree with Mr white
You need to wash new gravel thoroughly. It might be OK but a quick drain and wash couldn't hurt before adding fish.
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