水族馆氮气循环

称其为循环、硝化、生物循环、启动循环、磨合循环或氮循环。不管你用什么名字，每一个新建立的水族箱都会经历一个建立有益细菌群的过程。较旧的水族箱也会经历细菌群落波动的时期。不了解这个过程是导致新水族箱中鱼类损失的最大因素。学习它是什么，以及如何处理氮气循环中的关键时期，将大大增加你成功养鱼的机会。

废物问题

与自然界不同，水族箱是一个封闭的环境。所有由鱼儿排泄的废物，未吃的食物，和腐烂的植物都留在缸内。如果不消除这些废物，你美丽的水族箱会在短时间内变成一个粪坑。

事实上，在短时间内，一个新的水族箱确实会变成一个有毒的粪坑。水可能看起来很清澈，但不要被愚弄。它充满了毒素，很像一个化粪池。听起来很可怕，不是吗？幸运的是，一旦有鱼加入，能够将废物转化为更安全的副产品的细菌就开始在水族箱中生长。Unfortunately, they grow slowly and there aren't enough bacteria to eliminate all the toxins immediately, so for a period of several weeks to a month or more, your fish are at risk. This is the period of new-tank cycling.

However, you need not lose the fish. Armed with an understanding of how the nitrogen cycle works and knowing the proper steps to take, you can sail through the break-in cycle with very few problems.

Stages of the Nitrogen Cycle

There are three stages of the nitrogen cycle, each of which presents different challenges.

Initial stage

The cycle begins when fish are introduced to the aquarium. Their feces, urine, as well as any uneaten food, are quickly broken down into either ionized or un-ionized ammonia. The ionized form, Ammonium (NH₄⁺), is present if the pH is below 7, and is less toxic to fish.

Warning

The un-ionized form, ammonia (NH₃), is present if the pH is 7 or above, and is highly toxic to fish. Any amount of un-ionized ammonia (NH₃) is dangerous, however, once the levels reach 1 mg/L, the fish are in grave danger. Ammonia usually begins rising by the third day after introducing fish.

Second Stage

During this stage Nitrosomonas and Nitrospira species of bacteria have multiplied enough to oxidize the ammonia, thus eliminating it. However, the by-product of ammonia oxidation is nitrite (NO₂^-), which is also highly toxic to fish.

Warning

Nitrite levels as low as .10 mg/L are toxic and could be lethal to some fish. Nitrite usually begins rising by the end of the first week after introducing fish.

Third Stage

In the last stage of the cycle, Nitrobacter bacteria convert the nitrite into nitrate (NO₃^-). Nitrate is not toxic to most fish at low to moderate levels. Routine partial water changes will keep the nitrate levels within the safe range. Established aquariums should be tested for nitrate every month to ensure that levels are not becoming extremely high.

Water Additives

Now that you know what is happening, what should you do? Simple steps such as water testing and changing the water will help you manage the nitrogen cycle without losing your fish.

使用鱼店的氨气结合剂也可以解毒新建立的水族箱中产生的氨气，保持鱼的安全。每加仑水加入一到三茶匙的水族箱盐将减少亚硝酸盐对鱼的毒性。

从水族店获得细菌启动剂添加到你的水族箱中会加快循环过程，将其从4至6周缩短到一半的时间，甚至更短。这些产品添加了异养细菌，可以打破
分解废物，有些甚至添加有助于氮循环的酶。