Cycling tank and ammonia won't drop to 0

Hi,
I have been doing a fishless cycle on my tank for about 5 weeks. I thought the cycle was almost complete about a week ago, but my ammonia will just not drop to 0?
2 weeks ago, I had my first big nitrite spike, about 1 - 2 ppm. Then, within 2 - 3 days, there was no nitrite at all, and only 5ppm nitrate. I was assuming this was because there are no fish in the tank, and it is quite densely planted, so the plants sucked up a lot of nitrate. However, almost a week later, still no 0 ammonia. A week ago, I added some more plants and wood and my ammonia went from 0.25 to 0.5, I think from some pest snails that came on the plants pooping and new biofilm forming on the wood. Within a few days, back to 0.25. A week later, still 0.25! I have no idea what is going on. I tested my other tank to see if the test kit was faulty but got normal 0. I have done several large water changes, sucked up all the debris and biofilm I could find, cleaned the filter, trimmed dying plant leaves...
My tank is 33gal, and I was going to move my solo female apistogramma to the new tank when it dropped to 0, along with the small HOB filter to maintain the bacteria on it and ensure that nothing spikes after adding the fish. I've heard that 0.25 isn't dangerous to fish, and I am really tempted just to move her, but I don't want anything bad to happen. What should I do?

 

Hi fyrefish
Welcome to fishlore.

I can’t tell you what to do, but I can suggest what I might do in that situation.

A chart that mentions the safe level of ammonia at different temperatures and most importantly at different levels of PH


Some people on this site have mentioned this chart is even a little cautious or conservative and the safe level may even be a little higher?

You write of another tank.
Why are you doing a fishless cycle and not seeding your new filter in the other old established tank?

It was I think a mistake in a tank that is building colonies of bacteria to “ sucked up all the debris and biofilm I could find, cleaned the filter, trimmed dying plant leaves...” I believe all those jobs removed or disturbed the new colonies of bacteria.

If it were me I would not touch any hard surfaces until the cycle was firmly established.

What is done is done, so I suggest you just have to wait longer without cleaning the new tank.

You could rinse the filter of the old established tank into the new tank as well as add any old dirty ornaments into the new tank even if only for a month or two.

 

Did you use liquid ammonia to cycle? If so, how many PPM do you raise it to when you add it, and how long does it take to drop down to .25?

 

How are your plants doing? If they are decaying a bit as they settle into your tank, that could be causing the ammonia spike

 

Kinda like FishDin, I was going to ask what ammonia source you used to cycle this tank. You mention pest snails, but don’t say how many are in the tank.

Have you tested your source water for ammonia, nitrite and nitrates?
What are you using to test your water parameters?

 

I am using API master test kit. My tap water does not contain ammonia. My ammonia source is from fish food, but I haven't added any for a while. I think it's been coming from the pest snails. I have no idea how many there are, but there are a lot of babies every day. I would estimate up to 50, though it would be impossible to tell. They are breeding so much because of the large amount of biofilm on the newer wood I think, I don't know where else they would get food, as I said before I haven't added any food for a while and there is so far barely any algae. The plants are doing alright, anubias growing a few new leaves, swords getting a big larger, and the crypts spreading out a little more (I think, its hard to tell they grow so slow). There has been a little bit of algae and biofilm on the leaves, but the snails are beginning to eat that up too. As for ammonia dosage, I only added up to near 1 ppm, as there is only going to be a single small apistogramma in such a big planted tank, so i was going to let biological filtration naturally establish for when I add more more fish.
I tested my water tonight, and while not 0, the test is definitely less green than last night. According to the chart posted above, my tank's pH and temp is well within the 'safe' ammonia zone, so, after installing a DIY lid today I added my medium sized mystery snail to the tank, he seems active and happy eating the biofilm along with the bladders. My original plan was to move the HOB filter with the fish to preserve to bacteria, as I will take down the current tank when the fish moves. However, the new lid doesn't have any space for the filter, so I will just take out the media and put it in the tank when the fish moves. I will test again tomorrow, if there is no ammonia spike and it is either the same as today or lower, I will move the fish and add the media. I am also moving the cave/hide from the old tank with the fish, which has a very rough, textured surface, so I expect it will have some bacteria on it too. I know I could have probably safely added the fish today or earlier, especially considering how small of a bioload it will have on the big tank. I just want to take it slowly, and not make any mistakes.

 

UPDATE:
All is going well!
I added her into the new tank 3-4 days ago, and she is settling in nicely, and thanks to the cycled filter media I am getting nice clear yellow. She has claimed a 'cave' under some driftwood, which surprised me as she didn't go for her old hide, though she still seems to use it. I will get some pictures soon when she fully colours up. I am quite eager to add more fish, as she kind of seems bored by herself despite the much larger tank and likes to watch what I am doing from the corner. My plans for this tank are a school of corys (maybe 6) and a school of tetras, species still undecided though likely neons, as I really like their colour and are a lot cheaper than cardinals and other tetras, and especially since I plan on getting about 15 neons will put the least strain on my wallet. I will wait until at least a week has passed since adding this fish, and make sure the cycle seems stable. I was originally planning on adding tetras first and corys last, because I heard corys prefer more established tanks and can be fragile. However, the tetras would be a larger bioload at a time (I think) and buying like half at a time isn't really a good option as my lfs is not the most convenient place to visit. Any recommendations for stocking this tank would be appreciated, and some suggestions aswell as I am not 100% sure about the corys, I picked them mainly because they are quite cute and readily available in my area.

 

UPDATE:
All is going well!
I added her into the new tank 3-4 days ago, and she is settling in nicely, and thanks to the cycled filter media I am getting nice clear yellow. She has claimed a 'cave' under some driftwood, which surprised me as she didn't go for her old hide, though she still seems to use it. I will get some pictures soon when she fully colours up. I am quite eager to add more fish, as she kind of seems bored by herself despite the much larger tank and likes to watch what I am doing from the corner. My plans for this tank are a school of corys (maybe 6) and a school of tetras, species still undecided though likely neons, as I really like their colour and are a lot cheaper than cardinals and other tetras, and especially since I plan on getting about 15 neons will put the least strain on my wallet. I will wait until at least a week has passed since adding this fish, and make sure the cycle seems stable. I was originally planning on adding tetras first and corys last, because I heard corys prefer more established tanks and can be fragile. However, the tetras would be a larger bioload at a time (I think) and buying like half at a time isn't really a good option as my lfs is not the most convenient place to visit. Any recommendations for stocking this tank would be appreciated, and some suggestions aswell as I am not 100% sure about the corys, I picked them mainly because they are quite cute and readily available in my area.

Congratulations on the cycle!

Because I think your tank was cycled for a relatively low bioload (the highest level of ammonia mentioned in your posts above was 0.50 ppm), I’d suggest you add fish slowly.

 

My addition to Dunk2 statement is to do a few extra water changes each week for a couple of weeks or more. Sure you can use the test kit as well or instead, but my opinion is the eight minutes it takes as you wait for the results is wasted time if you end up doing a water change anyway. Just change more water more often any time you add more fish the any tank regardless of how old the tank is. That’s what I do always. Having burnt my way through 3 API liquid test kits at $80 Australian each I now reached for the fresh water bucket before testing tank water in a tank that you know you have added to the bio load.

in short
As the tank is new definitely test it if you have time.
If you are short of time smashing out a partial temperature matched conditioned water change never did any harm .

 

Oh, I will definitely be testing a lot, every day if when add more fish. If I see any ammonia, I'll probably do a water change. But what should I go for first, corys or tetras? Are there other fish that would be better suited to this tank? I'm probably going to go for corys first, because they will have a smaller bioload. The species will depend on what my lfs has of course, but I will try and avoid panda corys as I have heard they are fragile and don't do well in newer tanks.

 

Just a side-note: 0.25 is the usual value of a "false" positive when water containing chloramine is treated with a de-chlorinator. While yes, it is actually a positive (as ammonia is indeed present), it is chelated and thus not in a state that is toxic.

 

That's pretty interesting... I am fairly confident only chlorine not chloramine is present in my tap water but I will keep that in mind for future situations.
EDIT:
Hang on, nevermind I decided to check my city website again and chloramine IS being used to treat tapwater. That could very well have been what was happening, as I was also frequently water changing.

 

Classic. But at least this time it took only 11 posts.