Nitrogen vs. Ammonia

Question
Hello.

I have been cycling a tank that had already 1 year old cultured: Live Rock, Salt Water and Sand. I had to replace the Bio filter with a new one (normal hang-on filter). I've noticed some weird changes. When I replaced my filter I understood my tank might go through another cycle; however I felt optimistic about the pre-seeded items already mention in the tank. My question is it's been two weeks now and although I've noticed a short spike in ammonia, my nitrite levels read 0 and Nitrate is perfect. I've asked my local pet store thugs and they told me my tank was done cycling because my nitrite reads 0 and nitrate levels are perfect for inhabitants. Any light shed on this subject would be helpful. Thank you.

Kevin

Answer
Hello Kevin,

Anytime you make changes to the tank, add/subtract/move rock or sand, you will possibly create a 'mini-cycle'.  IT is important to understand that there is nothing called a cycle, but rather a cycle is a description of what is going on.

What is going on is, there is an increase or decrease in biological organisms that need to change to accomidate the new conditions.

When something changes, you are probably adding nutrients/'food stuff', which will force an increase in biological organisms.  (even if you remove rocks, you are increase food stuff in the process)

AFter the organisms grow in population, there will be a shortage of food stuff after they digest all that you stirred up.  Once they starve, some will die out, and in that process, create more food stuff, so there will be again, more food stuff.

That is a cycle.  (it/food goes up and down, organisms go up and down.)

It is important to understand that the test kits only test for specific elements or condidtions.  There is no test kit labeld, CYCLE, or ORGANISMS...  so there is no way to test to see if the cycle is complete.

You are basically looking at 'symptoms' of organisms growing or dieing, (the ammonia, and ability to process nutrient..And that process is like watching a pendulum.

You might get lucky and see the pendulum at the bottom, or center of the swing, and assume the cycle is complete, but to be sure, yo uwould need to take it slowly.

If your case, changing that type of filter should create too much havoc, and you should be okay after a short period of time.

If you do see any signs of ammonia increasing during that process, you can do a couple water changes during that time to help minimize ammonia poisoning.


Hope that helps.