I used the Vodka dosing method in my first sumpless tank. It, in combination with 'Nitrate Destroyer' effectively removed my nitrate problem. However, both require a skimmer.
Vodka makes the protien strings longer, making bigger bubbles and increasing the effectiveness of the skimmer.
Nitrate Destroyer is a bottled bacteria that will consume nitrate and convert it to nitrogen. They have very short lives and do not reproduce in an oxygen environment so daily dosing is required. Corals and other filter feeders will consume bacteria. Skimmer will as well.