After seven months of trying to get my tank to cycle with fish in, I repeatedly had high levels of ammonia and nitrates, never any nitrites. I was never able to work on my stocking list because every time I would check my water my levels would be sky high. For months I did water changes, added prime, added beneficial bacteria, pretty much everything that I was recommended. I did lose about a dozen tetras, no idea where they went. They disappeared several months ago and assuming that their bodies must be in the tank causing my spikes last weekend I decided to do a 90% water change and clean my canister filter based on recommendations from several different groups. At the same time I removed my pea gravel because I was told it might be causing my spikes due to debris falling under the gravel and not being cleaned up by the filter. I replaced with black diamond sand. When I cleaned my canister the water was pretty clear, I rinsed the bio foam from the top basket with aquarium water, I rinsed the ceramic rings in the middle basket with aquarium water and my third basket had been empty and at the recommendation of fish store I added clear Max and zero carb media to the third basket. I left the roughly 1 dozen danios in the large tank and moved my single ram over to an uncycled 10 gallon. When I put him in the 10 gallon I put 30 to 40% water in from the large tank, and kept the rest of the water that had been sitting in that tank for six months. Upon checking water samples yesterday, I found that my ammonia, nitrates, and for the first time nitrites were all off the chart in both tanks. I treated with prime and my understanding was that it would bind all three, and that I would see the result in a retest. I understand that it only last for 48 hours, and that water changes and more retreat would be necessary. However, this morning when I tested the water, my levels were just as bad if not worse than yesterday. It is only been about 14 hours since I put in the prime. 125g yesterday 10g yesterday 125g today 10g today I completely forgot that my daughter has a 10 gallon tank with a betta, a snail, and an algae eater. So I tested her water today... It has been recommended that I move some of the media from her tank into my 125 gallon. I have already pulled out two of her artificial plants and drop them in, but it has been suggested that I pull her filter off the back of her HOB and float that in my tank for a week. If I do that, will I be endangering the cycle in her tank? Is there something different I should be putting in my tank right now? I have the following in hand plus Seachem Stability. I am getting ready to take down the filter once again and add more ceramic rings to the second basket and also fillthe third basket with rings and remove the clear Max Anzio card as recommended from another. It has been suggested that I did not have enough rings to build beneficial bacteria. When I turn off the filter I will also be removing the intake and checking it as well as hose for missing fish. That is the only place I have not yet checked for the missing dozen. It is also been suggested that I add a sponge filter to the tank. I will be doing a 20% water change after I add ceramic rings. Am I missing anything? Is there something else I should be doing? I cannot figure out where this Tank has gone wrong.