Established tank fell out of cycle and hasnt reestablished after 2 months?

[Jac2694]

Situation:
About two months ago i did a large water change to my 55 gallon tank that has been established and running for almost 7 years. I cleaned the tank a little too well and removed too much beneficial bacteria from my tank and it fell out of cycle. I lost many of my fish due to an ammonia spike that at one point was reaching 5ppm. The filter that I have on the back of the tank is an emperor 4000 with the two biowheels. The filter has been dying out on me as of late with the biowheels stopping completely and drying out, which with the large water change is why I assume the tank fell out of cycle. Knowing that the biological filtration capacity of the emperor 4000 is low, I went and bought a canister filter by Ehiem that supports more customization for different types of filtration. I started the cycle pretty much from scratch about too months ago. I currently have one full grown blood parrot, two Krib cichlids and a pleco left. Im am running both filters at the same time currently, trying to establish the new Eheim filter during this cycle while still running my old filter.

Current Day (2 months later):
The tank is still not cycled and water quality remains cloudy and smelly. I constantly monitor the water to make sure that the ph is always at 7.0 because I know that the proper PH is needed for the nitrification cycle to occur. I have been adding Nite-out II every other day to the water to help the cycle re-establish and for a while it was doing the job. Ammonia had steadily declined and nitrates started to go back up. But now it seems that my cycle has halted. I'm not sure what the issue is. The ammonia never goes above .5 ppm and usually hovers around .25ppm. My nitrites always read 0 ppm and my nitrates are currently between 20-30 ppm. What can I do to help get the cycling process moving again for that remaining .25ppm of ammonia to dissipate?

Current water readings as of today:
Ammonia: .25 PPM
Nitrite: 0 PPM
Nitrate: Between 20-30 PPM
PH: 7.0

 

[hobby5]

Welcome to TFF!

Can we have a picture of your tank?

Are you sure your tests are working properly?

Anything rotting in there?

As the old filter is not doing it's job I would remove it completely. To help your tank and your fish (!) frequent (daily) and large water (80%) changes are mandatory till ammonia is down to 0 and the smell is gone.

Don't feed for the next days.

If you can get some filter mud of a running tank.
If you can get some floating plants.

Common pleco? Too big for a 55 gal.

 

[StevenF]

The bacteria don't just grow in the filter. They grow everywhere in the tank. I wouldn't worry about the filter on your tank unless there is no water flow. I had a water pump fail in my tank a couple of years ago during vacation. I had no ammonia and no loss of fish during the week and a half it was not working.

You probably have a water chemistry change of some sort in your tank. Or something could be dying in the tank (plant or fish). Also check the products you add to your tank Fertilizer, dechlorinator, etc. Perhaps on of them has gone bad. It also wouldn't hurt to list those here. Check with your water utility and ask if any changes have been made in the last couple of months. Perhaps that had to add more chlorine or changed water sources. Or perhaps you have too much organic material built up in the substrate. If so deep vacuuming of the substrate may be helpful. Do you know your GH KH values?