Help! High nitrates and nitrites

[rkeehn547]

Tank
What is the water volume of the tank?
20 gallons
How long has the tank been running?
6 months
Does it have a filter?
Yes
Does it have a heater?
Yes
What is the water temperature?
76 degrees
What is the entire stocking of this tank?
8 neon tetras
5 harlequin rasboras
1 molly
1 platy
4 peppered corys

Maintenance
How often do you change the water?
Twice a week
How much of the water do you change?
5 gallons on Sunday, 2 gallons on Thursday
What do you use to treat your water?
Tetra Aquasafe
Do you vacuum the substrate or just the water?
I vacuum the gravel each water change
*Parameters - Very Important
Did you cycle your tank before adding fish?
Yes
What do you use to test the water?
API freshwater master test kit
What are your parameters? We need to know the exact numbers, not just “fine” or “safe”.
Ammonia: 0 ppm
Nitrite: 0.25 ppm
Nitrate: Around 100 ppm
pH: 7.8

Feeding
How often do you feed your fish?
Once a day
How much do you feed your fish?
About a pinch
What brand of food do you feed your fish?
Tetra freshwater flakes and Omega One freshwater flakes
Do you feed frozen?
No
Do you feed freeze-dried foods?
No

Hello, today I woke up and noticed that my neon tetras were violently chasing and nipping each other. The other fish seemed stressed too. I tested the water and found that I had 0.25ppm nitrites and 100ppm nitrates! My tank has been completely cycled with no ammonia/nitrites and my nitrates never get above 40ppm. It may seem like I have too many fish for my tank size but I do water changes twice a week and the nitrates stay under 40ppm. I don’t know why my nitrates would be so high all the sudden and why I have nitrites in the tank. I added some aquarium co op root tabs a few days ago but I don’t think that would cause it. What would be causing this? Thanks

 

[LowConductivity]

Who really knows. Could be the root tabs. Could be water changes too small. I'd probably start upping the volume of water changes (50%/week minimum), if the increased volume doesn't help, next step would be to increase the frequency (2x/week 50% water change)

 

[StarGirl]

I agree on the too small of water changes. Even changing it twice a week you are still only removing 7 gallons a week. With a heavily stocked tank it is slowly building a little every week on you. Also when you change 50% a week it keeps your tank water closer to your tap water and there is less of a shock to your fish when you do a water change.