Oh, that's because of the potting soil mix. It's leaching tannins into the water. Just give it a 1-2 weeks or so, keep doing a lot of water changes and the tannins will go away in time. If you have any seachem purigen in hand, use some, it will help clear things up quick.
20 gallon - Sulawesi Golden rabbit snails/Japanese Trapdoor snails/RCS/Marbled crayfish tank
55 gallon - Rainbowfish Dutch scape low-tech planted tank
250 gallon - Community Tiger Oscar/Red hook silver dollar/Silver dollars/PB Jack Dempsey/Clown loaches/Tinfoil barb/Roseline sharks/Bala shark Monster fish tank