Currently there are 3 ways of dealing with nutrient export. Water changes which is pretty straight forward, a probiotic system, and utilizing plants to remove excess nutrients.
These include but not limited to Zeovit from KZ, NeoZeo from Brightwell, Ultralith from Fauna Marin, VSV Dosing ( Vinegar, Sugar, Vodka ), Prodibio and etc. Pretty much all the probiotic systems work on this simple principle. Feed the bacteria phosphate + nitrate + carbon + oxygen, let them grow and multiply. Use a skimmer to export excess bacteria out of the system, effectively removing the nitrate and phosphate the bacteria consumed out of the tank.
Zeovit - A system of utilizing Zeoliths in a reactor. Water is slowly fed over the rocks to grow a chain of different strains of bacteria on the rocks. As the bacteria grow and multiply, they exhaust phosphate and nitrate and carbon from the tank to multiply. The excess is removed from the skimmer. Thomas Pohl, the creator does not release info into what chemicals and bacteria is used in his system, so if you use this system, you are almost locked into it.
NeoZeo, Ultralith, - Are basically copies of zeovit. They work on the same principles.
VSV Dosing - This is the basic probiotic system. It utilizes the bacteria strains inside the system already to deplete nutrients. It just adds the last element needed for the bacteria to take off. Vodka, sugar, and vinegar are all different forms of carbon bacteria can use. Usually a bacteria culture could be added to jump start the bacteria population. Many users have tried Brightwell's Microbacter7 with great success. Caution should be paramount when dosing carbon. It can easily be overdosed with disastrous results.
- Vodka - - It is important to use a basic vodka without too much other additives. The main ingredient we're looking for is ethanol ( C2H5OH ). A decent vodka could have as much as 95% ethanol content. Ethanol is a fairly simple compound that can be broken down to release the carbon used for probiotic bacteria reproduction.
- Sugar - ( C6H12O6 ) Most likely glucose. Another simple carbon source. Different bacteria will favor either sugar, vodka, or vinegar. It is often recommended to mix it up a bit for different strains to proliferate.
- Vinegar - ( CH3COOH ) Mostly composed of water and 4-5% acetic acid. Another simple carbon source that can be easily broken down.
Biopellets - The new and upcoming star of the show. Vodka made easy. This is a solid pelletized form of carbon. In theory the bacteria will colonize the pellets and multiply on the pellets. It is important to keep the pellets tumbling in a reactor. This way excess bacteria is knocked off for the skimmer to remove as well as not promote anaerobic bacteria to form. I have had good luck using MB7 in conjunction with biopellets.