Help! Sudden Ammonia Spike! What Can I Do?

I have had a 46 gallon bow front since October, and I've never experienced a problem. I've always fed every 2 days, and I keep about 20 small fish in it. Recently, there was a small ammonia spike. I did a partial water change, and them put an aerator in it. All the fish were acting normal (except my angelfish, who has some sort of parasite). The next day, the ammonia had gone down from .5 to .25. I didn't have time to do a water change the next day. Today we tested it again. It's at 4. This was a big shock for me, being that it spiked so quickly. Seriously, .25 to 4 in a night. How can I get rid of the ammonia? The fish are still acting normal (ammo lock works well). I just need to know how I can get rid of the ammonia as quick as possible. I will put more ammo lock in and do a water change today.
Possible causes:
Lots of pest snails in my tank
Overstocking
Overfeeding

There is nothing dead in my tank, and I have no plants.

 

Do you have a filter that has been cycled in this tank? I would try to use prime to control the ammonia but it is not a permanent fix.

 

Do you have a filter that has been cycled in this tank? I would try to use prime to control the ammonia but it is not a permanent fix.

Yes, my filter is cycled and has been running for about a month now since my main filter broke. I'll try prime.

 

In the meantime, lots of water changes, those ammonia spikes are going to end up being fatal.

 

Prime helps up to a certain point but it is just a bandaid as is ammo lock. As I am sure you know, getting to the bottom of the problem is going to be the best fix. A properly cycled tank with enough media to hold sufficient BB should never register any ammonia.

You said that your tank has been up since last October but your filter broke and you have been using the new one for a month.

Did you move all the filter media from your broken filter over to your new one?

 

Prime helps up to a certain point but it is just a bandaid as is ammo lock. As I am sure you know, getting to the bottom of the problem is going to be the best fix. A properly cycled tank with enough media to hold sufficient BB should never register any ammonia.

You said that your tank has been up since last October but your filter broke and you have been using the new one for a month.

Did you move all the filter media from your broken filter over to your new one?

No, but we had the filter cycled already. Who knows, though. Might be re-cycling...

 

Sounds like your cycle is resetting and starting all over again. Otherwise the BB should take care of the ammonia. Have you thought about BB in a bottle? Not sure of the brands, but have read others saying it helped them

 

No, but we had the filter cycled already. Who knows, though. Might be re-cycling...

That is most likely what is happening. MinI cycles are kinda common when the filter media has been disturbed but usually complete quickly.