Question: Why won't my tank cycle??

My tank has been up and running for just over a month I think but I just can't get the levels right, ammonia -0.25 nitrite-5 and nitrate 20, my tank is 4 ft (140l) I have sand bottom, an air stone , 6 different plants all growing 6 big rocks one wooden hide and one feeding bowl and 3 axolotls I feed them 2 earthworms a day as if I don't they start picking on each other I keep the water temp at aroung 17c -19c also the filter is an Aquael fan filter 2+ which says its for up to 200l tanks I have mine on full but facing the back so no current I am doing 30-40% water changes twice a day clean poo up wen I see it I've swished the filter once since having it on as I didn't want to break the cycle and I've wiped the glass inside the tank twice I only have the light in when feeding, I just don't no why it won't work for me , please does anyone know why it won't cycle?.

What kind of dechlorinator are you using? If you're using any that 'bind ammonia', your tank will never cycle on its own.

Wiping the glass is probably a major culprit. Bacteria live on the surfaces of your tank, especially the glass. Wiping all the bacteria off doesn't help your cycle.

I'm using tap safe it worked on my warm water fish tank so thought it would be ok on this one it says its safe for cold and warm water

Have you tested your tap water to.see if that has traces?

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Hi yes tested and has traces then tested with tap safe and it was perfect I think I need to stop worrying at it will sort it self out my axolotls are fine

Maybe the filter doesn't have enough biological filtration to support the bioload.

I think I found the problem I brought a new filter for my fish yesterday and put it on pull power and was looking at my axols pump and it just wasn't pumping the same so I checked it and it had sand clogged in the mechanism and I just couldn't clear it so I cheated a bit I didn't want to lose any of the good bacteria so I swapped the sponge with the new fishes one and took it back to the shop for an exchange then when I got home I put the old sponge in the new filter and the new sponge back in the fish tank, I'm hoping this works, it's all working like it should and I get to keep the good bacteria.

Jennadenny said:

I think I found the problem I brought a new filter for my fish yesterday and put it on pull power and was looking at my axols pump and it just wasn't pumping the same so I checked it and it had sand clogged in the mechanism and I just couldn't clear it so I cheated a bit I didn't want to lose any of the good bacteria so I swapped the sponge with the new fishes one and took it back to the shop for an exchange then when I got home I put the old sponge in the new filter and the new sponge back in the fish tank, I'm hoping this works, it's all working like it should and I get to keep the good bacteria.

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Wait, what?

You took your filter (that you got sand in) to the shop that sold you a completely different filter, and exchanged it?

All becomes clear.