NO! DO NOT replace the sand. DO NOT add a heavier grade. Add a raw cocktail shrimp from the deli counter or fish store. This will aid in getting your cycle going. As the bacteria coat the grains of sand the sand becomes heavy enough to settle. I could not see my LR
for about a 4 days when I added my sand. Then I could only see the outline of the rock for a few more days. It took about a week for the sand to settle. At that time I removed my power heads, took them apart and soaked them overnight in white vinegar. That helped to remove the buildup and several rinses finally got them clean enouhg to go back into the tank.
Today I can create a major sand storm and it will clear within an hour. A minor one clears in a few minutes.
Of course if your power heads are too strong then it might never clear.