No Nitrite after 4 months (Fishless Cycle)

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DougA

Aquarium Advice Apprentice
Joined
Oct 21, 2021
Messages
13
I am starting a 20 gallon tank fishless. I have been trying to get it cycled for 4 months, but still cannot get any nitrite reading.

My readings are:

pH 7.6
Ammonia 4-6
Nitrite 0

I have performed water replacement several times, and each time I condition the water. I've also added a starter product. Six weeks ago I noticed that pH had dropped to 6, so I brought that back up to its current reading.

What else can I try? Thanks.
 
Is there a reason you are doing a fishless cycle? We get a lot of traffic on this forum and by far i see more issues with people not being able to complete fishless cycles as opposed to fish in cycles.

On the face of it, your ammonia could be a little high.

If your pH is dropping that could be a sign of low carbonate hardness. Low KH would cause your pH to crash and your cycle not to work. You are seeing both of these symptoms.

I presume you have a filter with filter media in it?

Are you seeing any nitrate in your tests?

Why are you doing water changes during a fishless cycle?

How did you raise your pH?

What starter product are you using?

What temperature are you running the tank at?

From another of your posts you have another tank, or is this the same tank starting over?

If you have 2 tanks have you tried to put a little filter media from your established filter into your uncycled one to seed the new filter with beneficial bacteria? If this is the same tank what happened to make you start over?
 
I agree it could be a kh issue or just a lower temperature prolonging the cycle time.

What type of water source are you using? City water in some places is very soft, near that of distilled water, which is not exactly ideal. The cycle relies on the nutrients in the water as well as the balance of the whole system. Low kh will cause rapid and wild ph swings as well as slowing or crashing the cycle.

If you are on city water you should be able to get a water quality report from them so you have an idea of what your putting into the tank. Ideally if your serious about being in the hobby for a while, get yourself set up with some test kits. They’re not lab results by any means but they can be extremely helpful in situations like this

What have you been using for an ammonia source?

Personally I think if you’ve got the ability to closely monitor the tank for the first 6-8wks, I would suggest just starting over with a fish-in cycle. I’ve had great success doing fish-in cycles even with a severely overstocked tank (ideally start with one or 2 small fish). It really just comes down to how much work you want to put into it till it cycles

If you’re going to keep going with what your doing. I would suggest a 50% water change then re test the ammonia. If your still reading 4+ In an hour, do another 50% water change. Get that ammonia under control and it should also help get some buffering capacity back in the tank
 
No nitrite

Is there a reason you are doing a fishless cycle? We get a lot of traffic on this forum and by far i see more issues with people not being able to complete fishless cycles as opposed to fish in cycles.

Answer: I read that a fish in cycle can be stressful and can kill the fish.

On the face of it, your ammonia could be a little high.

If your pH is dropping that could be a sign of low carbonate hardness. Low KH would cause your pH to crash and your cycle not to work. You are seeing both of these symptoms.

I presume you have a filter with filter media in it? Answer: Yes

Are you seeing any nitrate in your tests? Answer: Nitrate = 5

Why are you doing water changes during a fishless cycle? Answer: To keep Ammonia down

How did you raise your pH? My tap pH is high so I replaced tank water with conditioned tap.

What starter product are you using? Answer: Cannot remember

What temperature are you running the tank at? Answer: ~78

From another of your posts you have another tank, or is this the same tank starting over? Answer: Same tank, started over.

If you have 2 tanks have you tried to put a little filter media from your established filter into your uncycled one to seed the new filter with beneficial bacteria? If this is the same tank what happened to make you start over?
Answer: This is my only tank.
 
A fish in cycle, if done properly, can be done reasonably safely. Its much more likely to get your cycle completed as well. The sorts of issues you are seeing is very common with fishless cycling, and if i had been trying for 4 months with seemingly no progress whatsoever, i would want to see something swimming around in my tank and would go fish in.

If you are going to carry on with your fishless cycle, i would raise the tank temperature to 82.5f until your cycle is complete before dropping it back to whatever your fish needs.

I would recommend Dr Tims One + Only or Tetra Safestart. Do a redose.

Ditch the fishfood, and use an aquarium specific ammonium chloride product as an ammonia source. That way you can more easily dose to the level you need.

If your tap water is low on KH (check with your water company), then put a piece of cuttlefish bone in the tank or filter as this will be a steady source of KH in your water.

What happened to make you start over?
 
Fish-in cycle definitely has its risks, but can be done very safely even in the worst case scenario if you have the time and ambition to tend to the tank. I fish-in cycled a 36gal with over 30 comets in it, not ideal by any means but it was manageable with controlled feedings and 25% daily water changes

Like mentioned, fishless cycling has more than proven to be quite troublesome. There’s people that have been trying to cycle tanks for 6+ months and just can’t get it to go!

If you’re going to continue trying to do a fishless cycle, as stated above:

multiple water changes to correct the high ammonia levels

correct low kh (if that’s the case). Cuttlebone is quite often used

raise water temp, ~82° will help speed up the process

dose with a pure ammonia to be able to dose more controllably (take caution if you’re going to use a store brand ammonia as some will have scents added or surfactant which is basically soap)


Personally I would bail out on the fishless cycle at this point. I’d be wanting to see something in the tank by now. If I was you, I’d do a massive water change several times, get the water quality back to normal and go pick up a couple cheap ‘disposable’ feeder fish (feeder comets are 4/$1 here for the larger ones). I’d pick up 2 comets and plunk them in there and start fish-in cycling with them. If they die, yea it sucks but it wasn’t a big financial loss like losing a $50 fish if the water quality gets out of hand on you
 
No nitrite

I will change to a fish-in cycle. I do think my local water is low in kH, so I will buy a Cuttlefish bone and put it in the tank. I'll get the water reconditioned, use specific ammonia and the Tims or Safestart, and use just one or two starter fish. I cannot control the temp with the heater I have, so I'll need to leave that alone.

Thanks for the advice. I appreciate it.
 
Do not add ammonia if you are doing a fish in cycle. Your fish will be the ammonia source. Do you need advice on doing a fish in cycle?

Also, dont do a fish in cycle with fish you dont intend to keep or at least have a plan of what to do with when your cycle is complete.
 
Thanks

After my last post I realized that I should not use the ammonia with fish-in. I have read up on the fish-in cycle so I think I'm good with the process.
 
I finally obtained the following values from the lab that manages my county water:

pH 8.5-9
kH 9 ppm
gH 15 ppm

I added cuttlebone to my filter but I still had another pH crash, so I've put a second piece in there to see if that makes a difference.
 
Are you sure the KH and GH numbers are measured in ppm? That's really low, especially alongside such a high pH. They look more like the numbers you see for dKH and dGH.
 
Lab values

The lab told me ppm, without my first using that measurement term. Those values would seem to correlate with the tests I took with the API GH and KH test kit. KH is supposed to change from blue to yellow, as drops of the solution are added. Mine starts at almost clear on drop 1 and darkens to yellow. No blue. GH should move to green. Mine begins at very light (almost just tinged) green, and then the green darkens.
 
Thats an unusual combination of water parameters, (high pH, low hardness) but not impossible. Such low KH will effect your cycle though. 7ppm KH to cycle out 1ppm ammonia i think.

Are you seeing the cuttlefish bone increasing the KH?

How is the cycling going? Did you switch to a fish in cycle?
 
Cuttle bone

I added some cuttle bone but it did not help the kH and gH. So, today I added more of it to the filter.

I am doing the cycle fish-in. I have two Rasboras. They are active and seem to be doing well, but must be under stress due to the pH swings.

Thanks
 
Update and question:
i finally have a cycle started after about a month of adding cuttlebone, and trying to carefully monitoring pH. That is the good news.

However, I notice that whenever I do a water replacement of more than 10% my pH crashes (7.8 to 6). Can that be caused because my tap water KH and GH are uncommonly low, and even 20% water replacement can lower buffering to the point where it cannot maintain pH? If so, how can I raise the KH and GH level on the water I add to prevent that problem?
 
How long after your water change is your pH crash? How long does it take the pH to get back up? Possibly just disolved CO2 in your tap water that acidies the water, and as it offgasses the pH returns. I really doubt such small water changes could cause sufficient KH drop to lead to a significant pH drop.

What is your tap water pH straight from the tap? What is the pH after 24 hours standing?

Are you testing for KH now?

You have fish right? Are you seeing any issues with your fish after a water change?
 
Dropping pH

How long after your water change is your pH crash? Answer: Within hours.

How long does it take the pH to get back up? Possibly just dissolved CO2 in your tap water that acidies the water, and as it offgasses the pH returns. I really doubt such small water changes could cause sufficient KH drop to lead to a significant pH drop. Answer: I have not just left it to see if it comes back up. I did not know that could happen. I've been concerned that if I did not bring it back up with pH Up or a water change that the acidity of the water would stall the cycle.

What is your tap water pH straight from the tap? What is the pH after 24 hours standing? Answer: Per the county water lab it should be 8.5-9.0. I just tested it and it is about that now. I typically bring it down with pH Down prior to adding it to the tank. I try for 7.8. I know that is still a bit high, but given that it starts out so high I don't try to bring it down further, to avoid accidentally going too far down.

Are you testing for KH now? Answer: Yes, about once a week. After the cuttlebone had been in there its been about 5 for each. Per the county water lab it comes out of the tap at kH 9 ppm, gH 15 ppm

You have fish right? Are you seeing any issues with your fish after a water change? The fish seen fine after water changes. No change in behavior.
 
The test of 5 for KH? Is the dKH or ppm? The API test chart starts at 18ppm so i assume its dKH. Thats significantly higher than the the 9ppm (0.5dKH) you previously reported and a 20% water change even with 0dKH water would only drop it to 4gKH. Thats fine.

I really think you are mixing these 2 different units of ppm and dKH.

Its not the acidity that causes cycles to crash, its lack of KH. Your KH at 5 gKH is fine.

If you are seeing pH drops immediately after water changes, and you are adding pH down to your new water, it could be the pH down causing the pH crash.

Are you adding pH down to new water, then pH up to raise it again after it drops? I would be really interested to see what your tap pH is after its had chance to degas and stabilise. Fill a bucket with water and test it after 24 hours.

If the fish are fine i wouldnt worry.
 
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