From what I understand, removing Nitrates is near impossible..
Heres what I have picked up over the years..
The large display tanks found in Las Vegas casinos, do not do ANY water changes.. They have huge sand filters, which somehow have a source of bacteria that actually breaks down nitrates. I have no physical evidence of why or how this happens, but I understand they never change the water, and the nitrates sits at around 200ppm at all times..
Nitrates are used VERY little by plants, but infact it is Ammonia/Nitrite that is consumed by plants in the prior stages of the nitrogen cycle. Some plants and algaes do use more Nitrates than others, but the 'less nitrate' effect that most people see in a planted aquarium, is the ammonia/nitrite being consumed in an earlier stage.
Chemicals can be used to chemically 'bind' Nitrates, Nitrite and Ammonia. These are sulfur based chemicals, such as AmQuel and Prime. Keep in mind, They are just 'locking' the Nitrates into a less harmful substance, and not actually removing them. So when you chemically bind your Nitrates, that leaves less 'clean' water open to saturate the new incoming nitrates, thus leading to a higher concentrate of both regular nitrates and chemically binded nitrates.
Sulfur Reactors, often used by large public aquariums. Even though they are not very reasonable for a domestic usage, I have seen some people who have learned and installed these into their large home tanks. They are huge reactors (look like calcium reactors for SW), that are full of sulfur.. The water slowly flows through the sulfur, and it chemically binds the Nitrates within the sulfur, not allowing them to be released into the tank (Like AmQuel).. Eventually the Sulfur will become exhausted, as it's effect is very similiar to zeolite with ammonia. The problem with these is when doing maintenance, if you happen to do anything incorrectly or leach any contents of the sulfur reactors into the main system, you could poison the entire tank.
I have seen a few other 'miracle' filtration systems like the Aqualizer and other misc gadgets, but I think it's all speculation. This bakki shower sounds very interesting, as I would like to hear more about it. I am starting to believe there is a bacteria that does eat/breakdown nitrates, but it's very hard to harbor this bacteria and keep it alive. Perhaps the massive sand filters that are operated on such a huge scale, have enough oxygenation and surface area to generate this 'de-nitrate' bacteria, but I have no clue. I would love to hear more scientific reports on the matter..
I would go with a planted refugium, if I were you.. It's inexpensive and cost-effective, and if done properly it could also be functional as a grow out tank or display tank. I have pictures of how to create one, and would be willing to help you with any ideas..
Hope that helps,
Miles