High nitrites

[lflores]

Hello everybody!
I stated a Freshwater aquarium like 5 weeks ago.
I did fish-cycling. At the two weeks of having the tank running, I added the first fish. I use the API master kit to test the water ranges. It was very high ammonia, and low nitrites.
When the ammonia went down, I added another fish, (both of my fish are marbled mollies, and recently added a Chinese algae eater) and the nitrites were down, and ammonia down.
All of a sudden nitrites spiked all the way to 5 ppm. The ammonia is still at the lowest level. For a whole week i performed a 25% water change in the tank. Nitrites keep showing 5ppm.
I don't know what to do. The Tank has been running for about 5 to six weeks, I am not completely sure. Today I tested for nitrites and it is still very high.

Tank Specs:

10 gallon
Fluval C3 filter 5 stage filtration (has not been cleaned to preserve beneficial bacteria)
10 pounds of Gravel
Thermostat, set at 80F
Air Bar, Under gravel.
Three plants,
Natural Rocks from Kenucky.
2 Marbled Mollies
1 chinese algae eater

The fish look just fine, any of them has red gills. But i am worried about the nitrites they are suffering aren't they?
Please help!
I appreciate it!

OX

 

[Berylla]

Water change 50% every day until your reading are 0 ammonia 0 nitrite and 10-20 nitrate. Your tank is not cycled yet. If your fish looked stressed change the water a couple of times a day.

 

[lflores]

Thanks Berylla, Will do.
I am just wondering why they wont go down. They have stayed like that for the past week.
Ill let you know how they go in a week or so.

 

[threnjen]

It just takes a long time to build the bio filter. Fish in can take many many weeks.

 

[librarygirl]

Hi and welcome! Adding the CAE while the tank was cycling probably wasn't a good idea and caused the spike. Do more frequent water changes (at least 1-2 a day of 50%) until nitrites go down. Also check your tap water just to make sure it doesnt contain nitrites or ammonia, etc. Just FYI, the CAE doesn't really belong in a 10 gal. It can grow very large and usually get very aggressive and destructive as they mature. I would try to rehome it if you can.