A couple weeks ago I switched my 10 gallon tank with a betta to sand bottom and a peice of Mopani wood from the LFS. Ever since then, the water has had an orange tint to it that won't go away. I've changed water three times. And every time for a couple days, it looks nice and clear and then goes right back to the orange. Is there something I can do to change this? I'm assuming it has something to do with the wood and/or sand.