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Discussion Starter · #1 ·
Hi all, Looking for some input with some issues with the nitrogen cycle of my tank. Sorry, this is a long post, but I tried to include all the details in case I'm overlooking something important.

If you don't care to read the details, My filter has been cycling for 6 weeks. There have been fish in the tank for 3 weeks (added after I thought the fishless cycle was complete) and I've been doing daily 50% water changes and 5x dose of prime to try to keep them alive. I keep getting nitrite spikes and trace amounts of ammonia. The PH in the tank is 6.4 (due to buffering substrate) and the tap water PH is 7.4. I temp match the water change water, but I'm wondering if the ph swing could be killing my beneficial bacteria.

I have a heavily planted 29 gallon tank. I began the fishless cycle in a 30 gallon tote that was also used to water log a piece of driftwood. The filter ran in the tote for 3 weeks while I maintained an ammonia level of 1-2 ppm. By the end of the 3 weeks, the ammonia was dropping to 0 in 48 hours, I never saw nitrites, but only started testing for them during the last week after ammonia had been dropping consistently, so I assumed I missed the spike. By the end of the 3 week time frame I was reading around 10 ppm of nitrates. At that point, my plants had arrived in the mail so I added ADA aquasoil amazonia ver 2 (which is supposed to leech ammonia) and did the daily water changes (as recommended by the manufacturer). After the first week of daily water changes, I saw my ammonia dropping and my nitrates increasing, but still no nitrites. I completed the 2nd week of water changes every other day, still seeing 0 ammonia and nitrites, and nitrates would rise to 10 ppm before each water change. At this point I figured the soil was still leaching ammonia, but the beneficial bacteria had established enough to take care of it, so I added 7 neon tetras and 2 ottos. I monitored water parameters daily for 3 days and still saw 0 ammonia and nitrites, so I added 5 more neons and 6 corys. The same day that I added the additional neons and corys, my nitrites spiked, I immediately did a water change and continued to monitor the water, Over the next 3 days I lost a neon each day, but got 0 ammonia and nitrite, so I assumed the spike was just a blip and the fish deaths were due to neons being fragile (they came from a different shop than the first batch). Since water parameters were still good, I added 10 more neons for a total of 18 neons, 6 albino cories and 2 ottos. Since then my nitrites have risen to 0.25-0.5 and trace amounts of ammonia every day for the past week.

As mentioned above. I've done a 50% water change and a 5x dose of prime every day to keep the fish alive, and have not lost any more fish since adding the last group, but the nitrites still return every day.. Could the difference in PH between tap and tank water be killing the beneficial bacteria? Am I stunting the cycle by changing the water every day?

Thanks to anyone who took the time to read this, I appreciate any advice.
 

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You already know what the issue is - you rushed before the initial "cycle" was complete.

That pH swing isn't the source of the problem. It's just that everything you need isn't yet established. Adding Amazonia kind of started everything over because of the amount of ammonia it releases.

If it were me, I'd remove all the livestock and bring the tank up to 3ppm ammonia every day. Once it can process that in less than 24 hours, nitrites have disappeared and you have consistent nitrate readings, the tank is ready.

If you can't remove livestock, you'll just have to keep up with water changes and dosing Prime until everything settles down. It can take a while for new tanks like this to stabilize.
 

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Discussion Starter · #3 ·
Thanks, you're right, now I know the tank wasn't completely cycled. I thought it was but I was obviously wrong. I just wanted to make sure that the difference between the low PH in the tank caused by the aquasoil, vs the higher PH in the tap water that is used during water changes wasn't harming the beneficial bacteria (or some other issue with how I'm caring for the tank that was stopping the cycle).
 
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