Yellow water can be caused be organics that have been decomposed in the water. Drift wood can also cause this too, as previously stated. I once had this problem oddly enough after a long time of researching the only things I could find that could clean the water of being yellow was either carbon, or water changes. And both work well. But with the carbon you need to use lots or it will only last 3 days try both. As for the cloudiness that means bacteria bloom and could be attributed to you changing "all" the water which is never a good idea. The bacteria are multiplying at such a high rate to compensate for your water change, that they are visible by the naked eye. If the water parameters are healthy for the fish jsut leave it alone for a while beacue you did a water change. You may want to take out the driftwood but I still have mine and my fish love it even if it does make the water yellosish,,,carbon works great try that. The lighting does sound alittle off unless you have plants what kind of lighting equipment do you use? and What kind of bulbs are you using?