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did my cycle crash?

3K views 5 replies 4 participants last post by  HUNTER 
#1 ·
so I'm on day 18 of my fishless cycle dosing ammonia. The tank is a 55 gallon with a 1xT5HO Hagen Glo fixture and Rena Filstar XP3 filter. The temp has been steady at 82F. I've been planting some here and there as I slowly get more plants, but it is not heavily planted.

For the last 10 days my nitrites have been reading off the chart (with API liquid test kit) so I was doing water changes daily to bring them back down to a readable level. During this time, I was dosing ammonia to keep it around 2-3ppm, and the nitrates were increasing slowly. I would do a water change in the morning (if the nitrites were not readable) but by the afternoon they would be off the chart again. The ammonia would always be down to either 0 or 0.25ppm after 24hrs.

Yesterday, we added an air stone to break the surface tension in one corner of the tank and planted some jungle val. I also skipped dosing ammonia because I wanted to give the nitrite>nitrate bacteria a chance to catch up (and I didn't do a water change).

This morning the water parameters read:
Ammonia: 0.5ppm
Nitrite: 0ppm
Nitrate: 5ppm


I would have assumed that the cycle had finished since the nitrites fell, but I'm a little concerned because the nitrates so low and the ammonia isn't at 0. I dosed back up to 2ppm a few hours ago and figured that I would check the parameters tomorrow morning and see what happens. Is this a common thing to see at the end of a fishless cycle, or did something happen that crashed the cycle?

edit:
well, I realized after I typed that out that I didn't include the pH values. normally the pH was hovering around 6.8-7, but now the pH is up around 7.8. I have no idea what happened, since I haven't added anything extra recently, the bubble stone is on a very low setting, and there is still a piece of driftwood in there that helped it stay slightly acidic. I guess this is where the problem occurred and it crashed, so I have to start the cycle again?
 
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#2 ·
I too was confused about the kind of ph rising in my tank. One of the experts in this forum suggested that it could be because of CO2 loss.
Ph would be low as soon as water change and would rise to higher value (real ph of your water) in 24-48hrs. CO2 gassing out is probably happening. It was true in my case.
To confirm, keep your water in a separate container and measure ph.
 
#3 · (Edited)
You shouldn't do water change during cycle especially theres no fish, you're just delaying the cycle. Nitrite is the longest to go away and yes, the reading will be off the chart and suddenly drops down to almost zero when there's enough bacteria to consume it. If you have enough plants, they'll consume it as well. Also, when the ammonia drop to zero, dont add anymore ammonia, you can put little fish food to maintain the ammonia eating bacteria.
 
#5 ·
I was doing water changes based on Diana's advice in this thread http://www.plantedtank.net/forums/showthread.php?t=186129


google this
api test kit gives false reading?
What do the search results make you think about the cycle
Thanks for the hint. It does seem as though a false positive could be responsible for the ammonia reading this morning (as I have seen this in my other tanks periodically), but I was more confused by the nitrates. I know I was doing water changes, but I thought the nitrates should have been higher. Now I realized I screwed up a conversion in my head and it is most likely fine.

I tested the water again a few minutes ago (out of curiosity) and the ammonia was just over 1ppm and the nitrites were back up around 2ppm, so it doesn't seem like anything is severely compromised. Hopefully tomorrow I'll wake up and find both the ammonia and nitrite to be 0.

thanks for the help!
 
#6 · (Edited)
Doing water changes while fishless cycling will just prolong the process. Once you reach the target liquid ammonia let say 5ppm, then just wait to do it's thing. Nitrite will always be off the chart and the nitrate is not going to be accurate as well. If you do water changes to bring down ammonia or nitrites, it will not establish the proper amount of bacteria and everytime you put fish food or any source of ammonia, it will register. Cycling is a long process that no one wants, unless you have tons of plants. People always wonder when they see high readings during cycle, it suppose to be like until it's populates bacteria. If you're still reading ammonia and nitrite, you'll still have few days or weeks but it'll happen. No more water change until the first two are zero, then check your nitrates and do water change to bring it down to where you want it.
 
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