Nitrogen Cycle Shortcuts, Tips and Tricks

Water Change Done Right, Nitrogen Cycle Made Easier

Dr. Thomas R. Reich PHD and his many books

Dr. Thomas R. Reich

In an established and well maintained healthy aquarium, the nitrogen cycle processes waste and keeps levels of ammonia, nitrites, and nitrates at a safe minimum. This process is helped in the closed aquarium environment by occasional partial water changes and the immediate removal of any waste material from the aquarium, whether that be dead fish, plants or excess food.

Here are some of Dr. Reich’s tips and tricks for both starting the nitrogen cycle in a new aquarium, as well as for maintaining a healthy nitrogen cycle in your aquarium for years to come.

Borrow a Cup from a Friend

The point of establishing the nitrogen cycle is to establish good bacteria within the aquarium system. This “good bacteria” is what breaks down the bad nitrites into the more manageable nitrates. It also starts a process called denitrification. In deeper, compacted substrates and other areas of zero oxygen (sometimes in the filter or under at least two inches of good aquarium gravel) anaerobic bacteria strip nitrate of its oxygen atoms and release nitrogen gas (N2) in the process. The N2 is then consumed by live plants.​

When you start a new aquarium, ask a friend with a healthy, well-established aquarium for a cup of gravel from deep on the bottom of the substrate. Yes, this looks very dirty. But it is full of anaerobic bacteria, that which we discussed above. One small cup (unwashed) put on the very bottom of your new aquarium and then covered with at least two inches of new aquarium gravel and filled with aged water (see the third tip below) and you will cycle your aquarium in less than three weeks as opposed to three or four months the traditional way.

Always Have Live Plants to Improve Nitrogen Cycle Effectiveness

Live plants make aquariums healthier, allow you to have larger populations of fish, give your fish something to snack on and hide in, and improve the beauty of any aquarium. More importantly, they consume nitrogen and exhale oxygen.

One of the key roles played by water plants in nature as well as in your aquarium is in the nitrogen cycle. The fish’s waste, in the form of ammonia, is broken down by beneficial bacteria first to less toxic nitrite and then to nitrate.​

High nitrate levels are not recommended and occur even after the nitrogen cycle has been established. To reduce the amount and frequency of water changes nature gives us live plants. Not only do the plants “breath” the N2 and exhale oxygen as explained above, but live aquarium plants also consume nitrate as fertilizer to assist growth, which reduces the nitrates in the water, makes the plants bigger, so they “breath” more N2, exhale even more oxygen and eat even more nitrate.

The addition of live plants to an established aquarium will also reduce algae, since the live plants will eat the plant food (nitrates) and breath the N2, more efficiently than the algae. In many cases, a well-planted aquarium has no algae problem having starved out the algae entirely.

Proper Preparation of Water for Water Changes

This is the most simple tip of all, no chemicals, no wild apparatus, though many chemicals and devices are needed for Discus and other specialized varieties of fish. But for a good, well-established community aquarium do the following:

  1. Acquire one or two empty five-gallon water jugs
  2. Fill the jugs with tap water and set in a corner out of sunlight and uncovered. The area you place the filled five-gallon jug should be in the house, not in a garage where smoke or gasses could dissolve into the water.
  3. Let the uncovered jug or jugs of water sit for at least 48 hours, but up to two weeks are ok. (Longer than two weeks and the water could go stagnant, or become stale.)
  4. Drain out no more than 25 percent of your aquarium's water and replace it directly from the “aged” jugs. "Aged water" means tap water aged 48 or more hours.