Nitrite spike

Question
My ehiem filter broke a month ago and so, to save money, I had it all completly replaced by the company with a brand new filter. I felt this was my only option as a thought a new filter was better than no filter at all. However, I feel like a complete fool now.

I am aware of nitrite and ammonnia spikes but I have never suffered from them before. The new filter has been running fine with no issues for about 2 weeks now but I currently have a nitrite spike between .5-1.0 mg/l (I only have dip tests so can't be very accurate) and I know it is due to the new filter not having the correct bacteria colonies in it yet. Nitrate and ammonia are at 0

I have already lost all my amano shrimp and my fish are gasping and hanging near the surface (this has all happened whilst I was at work today as all were normal and alive this morning). I have since done a 30% water change and added an air pump to try relive the fishes stress. I am planning on doing 2 30% water changes a day and not feeding them for the next few days to try and prevent any excess waste.

I guess my question is.
How long can is this going to last and how can I help them?

I had read that adding salt will help but I have loaches
I have read that new filter media will help but that just seems ridiculous
I have read that I have to do 3, 30% water changes a day but again that seems to me like the filter will never gain it's proper bacteria colony if I do that
And I have read to add a product called Stabilizer? but I don't think that is even available in England.

I am worried that turning off the tank lights tonight (I say tank lights, they were short-circuited when I was changing the two filters over and had to be sent away for repairs, so at the moment I have a desk lamp shining in the tank) will raise the CO2 too high and kill the fish so I'm going to leave the lights on tonight to try and keep O2 at it's maximum levels. I think i'll do another water change before i go to bed too.

I hope you can give me some good advice.

Rachel

Answer
Rachel,

What is happening is the filter is cycling. DO NOT do more than one water change a day. You can do a 30% today. Check the nitrite level daily and if it is up do another water change. Do this every day until the levels are back to zero. If the fish are gasping at the surface, that means they do not have enough oxygen in the tank. Adding a couple of air stones to the tank will help this problem. You should not add salt to the water with the loach's in the tank. New filter media will just start the cycle process all over. Just keep the ones you have going. It is always harder to cycle the tank with fish init but it can be done. Adding any kind of stabilizer will be a waste of time and money because they do not work. You will want to turn the light off since it is a desk lamp if left on too long you will add algae to the mix. It is ok to turn off the light at night. The main thing is to keep the water clean and oxygenated. Let me know how everything is going tomorrow.