Help with my unstable tank cycle

Question

i have recently cycled my tank and yesterday morning i tested the nitrite and it was 0 ppm and in the night time i tested it and it was 0.25 ppm. and it repeated today again. what can i do to fix this problem? please i need help.

Answer 1

keep cycling it. its probably not fully done

Answer 2

Your tank is cycled?  What were your readings for the past week?

When did you notice your ammonia spiking?  Having a nitrite of .25 and then a 0 isn't an unstable tank.  Most tanks will jump ammonia included between 0 and .25 depending on a few things.  Rarely do new tanks hit the 6+ mark for ammonia unless you are adding bottled goo or overfeeding an empty tank.

How many fish were added, were the fish over fed, were plants added to the tank.  Ammonia and nitrites will spike with the addition of items like fish, plants and inverts.  This is normal.

Did you do a water change recently or did you just get done with the cycle?

If your nitrites are remaining under .25 chances are it is just now coming out of cycle.  Give it a day or two to stabalize.

Answer 3

Need more info to help you...

Did you add any more fish?  How long did you cycle (from start up to now)?  Have you checked for ammonia?  What are you using to test with - strips?  Drop kits?

I recommend the liquid drop kits for testing - strips can be far less accurate.

In case you need more info about cycling (since you didn't mention anything about testing for ammonia...), here's some info from one of my previous answers:

(sorry if this is too much info...)

All tanks need cycling! Like every living thing, waste is produced through breathing and excretion from digestive processes. In layman's terms, fish produce waste products from breathing and pooping. All fish do this. A cycled tank has the right balance of good bacterial colonies present that convert the fish waste product (ammonia, harmful to fish) to nitrite (also harmful), then nitrite to nitrate (safe up to a certain level). Without these good bacteria, waste products build up in the water and cause damage to fish gills and internal organs. Think about a fish swimming around in it's own pee/p**p - yuck.

Okay, the process... There are many methods and experts won't agree on which is the best. The best method for YOU is the one you can do in its entirety, from set up to cycled without causing harm (or death) to fish.

You can choose to cycle with fish, but you risk damaging or killing your fish if you don't watch the waste levels closely and take corrective steps. Cycling without fish is a great way to achieve results without endangering fish, but it can be more difficult. Either way, patience is necessary to see the process through. It can take well over a month to properly cycle a tank.

Cycling with fish - get a few small fish and introduce into your tank. Test daily for ammonia and nitrite for the first couple of weeks. You must perform tests with liquid drop kits or test strips, although test strips aren't as accurate. If you are cycling with fish, I recommend the liquid kits. You'll see a gradual increase in ammonia first, then after a time a gradual increase in nitrite. Both of these can be reduced with frequent partial water changes. Make sure you use some sort of water conditioner because chlorine will kill any beneficial bacteria colonizing in your filter media, and your tank will never cycle. Both ammonia and nitrite will reach their maximum and then you'll begin seeing nitrates. Gradually, your ammonia and nitrite levels will reduce to zero. A tank is cycled when ammonia and nitrite levels are zero and you have nitrates (the end product of your bacteria colonization).

Cycling without fish would require you having access to at least a handful of gravel from an already cycled tank or some filter media from an already cycled tank. The cycling process will proceed as above, but you'll need to find some sort of ammonia to "feed" the developing bacterial colonies. Some recommend distilled ammonia being added every other day or so. Some recommend "feeding" your tank with fish food, a little bit a day. The uneaten food will fall and begin to decay, producing ammonia.

There's lots of info on the web - do your research.

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If you had no nitrites one day, and then some the next, you may be in "mid-cycle".  You are not completely cycled unless you have no ammonia, no nitrite, and there's evidence of the end product, nitrate.

Answer 4

impossible to answer without more info. have you added any fish? how long has your tank been set up and how long has it "cycled"?  Did you see ammonia, then nitrite, then a nitrate spike? if not you havent fully cycled. depending on the size of the tank, adding fish can cause another mini cycle.  

Answer 5

you haven't cycled your tank it is just starting the cycle process

if you have fish in the tank you better be testing for ammonia it will kill the fish before the nitrite does

you say you cycled your tank I am guessing this means you set it up and let it run for a while well the bad news is that is not cycleing a tank

the cycle process will have an increased ammonia and nitrite level sometimes as high as 6.0 and then they will drop down to 0 when the cycle is done

if you have fish in the tank you want to test the ammonia level daily if it goes above 1.0 do a partial water change do not touch the gravel

this process can take as long as a month before the tank balances out and finishes the cycle process

if you try to fix the readings with chemicals you will more than likly just cause the cycle to take longer and prevent it from ever finishing