The “Old Aquarium” Syndrome

Just when you feel that everything has settled down and that your aquarium is doing
extremely well, disaster strikes. And you don't know why! The water seems crystal clear,
there has been no fish loss and your plants also look very healthy. Then, how does the
sudden loss occur?
This is called the "Old Aquarium" syndrome. In a closed aquarium, the balance in the
aquarium is dependent on many factors. The closed aquarium is actually precariously
poised when it comes to equilibrium. Everything in the aquarium affects the other things
in one way or the other. Even water evaporation causes the impurity level in the water to
rise as only water evaporates. This leaves behind the dissolved wastes as well as any salt
you have added to the water.
When you take the above into account, you will notice that there will be a continuous
decline or accumulation of various elements in your aquarium. But the fish, once it gets
habituated to your aquarium, will adjust to these changes and initial signs of stress may
go unnoticed too. Lack of proper maintenance will add to the potentially dangerous
situation, and this will prove disastrous to your fish in the long run.
Most of the times, the problems will start snowballing when you add new fish. Often,
people blame the store for giving them infected or stressed fish. In reality something
totally different is happening. The fish in the store were used to a more stable and
probably healthier environment. When they are introduced into your aquarium, they will
be shocked and stressed by the harsh conditions in your aquarium. The older inhabitants
in your aquarium have already adjusted to this, albeit slowly. The shocked fish will be
susceptible to diseases and once an infection has developed in your aquarium, it will
catch on like fire. All the fish will soon show signs of stress, affected as they are by the
negative conditions in your aquarium.
Rising nitrate levels show the first indications of the "Old Aquarium" syndrome. If left
unchecked, the pH level in your water will drop drastically. This will in turn affect the
beneficial bacterial growth in your aquarium. Ammonia will start building up in your
aquarium. Even at this stage, noticeable signs of danger are not seen in the aquarium,
except in the basic water parameters. When the pH level in your aquarium is below 6.0,
this high level of ammonia will not affect the balance in your aquarium. But the pH level
may go up due to additives used, or due to evaporation etc. Then, the ammonia becomes
toxic.
There is only one way to remedy this: frequent water changes. Regular maintenance of
the aquarium will keep the "Old Aquarium" syndrome at bay.