We discussed the nitrogen cycle before and how it produces nitrate or nitrogen gas. Now let’s talk about how to remove that from our tanks.
As discussed previously, water changes is a simple way to remove nitrates from the water. By removing old water and replacing with new water we reduce the levels to safe ranges. For smaller tanks this might be the only step you need.
For larger tanks where doing a bi-weekly water change is harder to accomplish, something to consider is carbon dosing. This process puts a source of carbon into the tank that feeds bacteria to, in turn, consume the nitrates in the tank. Some sources of carbon include vodka, vinegar and Red Sea’s NO3PO4x (also called NOPOX) and have to be dosed daily either manually or with an automated dosing pump. A more laid back approach is the use of biopellets, which allows you to set it up and leave it for months on end but doesn’t allow the same control over how much you dose compared to the daily dosing products. The only drawback is carbon dosing has to have a protein skimmer in order to catch the bacteria and remove them from the system. We’ll talk more about protein skimmers in another section too.
Algae Turf Scrubber
Another way to remove nitrates and combat algae is with algae! Algae is a very fast growing organism that consumes nitrate as well as phosphates. By growing algae in a special and dedicated area we can compete with algae growing elsewhere in the tank. You can buy a premade algae scrubber or make your own. There are two types of scrubbers. One is an upflow scrubber that utilizes airflow to move water up a screen and the other is, you guessed it, a downflow scrubber where water flows down over a screen. Both types need light to grow algae and every now and then the screen is cleaned off, removing nutrients from the tank.
Most commercially available scrubbers are downflow models. They use a simple pump to get water above a screen and let gravity pull it back down. A simple design to make your own is to use a cheap fountain pump, a little pvc and a sheet of plastic bought from most hobby stores. Using a simple home depot light reflector and a small cfl bulb you can light both sides of the screen for maximum growth.
Upflow scrubbers are popular for the DIY crowd and tend to be fairly cheap. You need a container to hold your screen in place and an air pump with tubing. If you had a freshwater tank you might have an old air pump laying around already. Basically the idea is the air pump puts air into the bottom of the screen and as bubbles rise, water moves with it. I will say unless you have some magic air pump, there will be extra noise here. The container helps to hold the screen in place and allow air bubbles to pop inside it, thereby containing salt creep.
Have any other ways you like to reduce nitrates? Comment with your favorite method!