Fishless Cycling Problem

If some ammonia has gone, it must have gone somewhere. In fish tanks there are two possibilities.

When a tank has live plants, they use ammonia as fertiliser so as they take it up the reading drops.

When a tank has no plants, there must be another reason. Something is eating the ammonia, usually the ammonia eating bacteria. They turn the ammonia into nitrite.
1 ppm ammonia -> 2.7 ppm nitrite so if you've lost 0.5 ppm ammonia that would have made 1.35 ppm nitrite. But your nitrite is zero.
Just supposing you had enough nitrite eaters to turn that 1.35 ppm nitrite into nitrate. 1 ppm ammonia -> 2.7 ppm nitrite -> 3.6 ppm nitrate. So your missing 0.5 ppm ammonia would have been turned into 1.8 ppm nitrate.
This is a bit trickier because our nitrate testers aren't good enough to pick up a rise of just 1.8 ppm.

Are you using API liquid testers, and does your nitrite tester goes a nice sky blue after the 5 minutes with not even a hint of purple?



I think the way to go is to add 3 ppm ammonia and see what happens. If that drops to zero, it should make 8.1 ppm nitrite, which is off the top of the scale. That nitrite would be turned into 10.8 ppm nitrate, and a rise of nitrate that size should show up when testing. Just make sure to shake the one nitrate reagent bottle and test tube as per the instruction or you'll get a false reading.

I must say the Nitrate seemed slightly darker today, so might be nearer 5ppm than the 2.5ppm I quoted. And yes, bottle and tube shaken as recommended. Using API testers, Nitrite is blue, no hint of purple at all. Should I try shaking the Nitrite bottle just in case?

I usually shake all the bottles a bit, but shake nitrate #2 very hard and long.


Since it is known that Tetra Safe Start contains the right species of nitrite eaters, there is the possibility that you might not see any nitrite. The proof is going to be if your nitrate increases as ammonia drops. But to see any increase in nitrate you'll need to add more than 1 ppm ammonia as that won't make enough nitrate to be certain of an increase.
I'd go with adding a 3ppm dose of ammonia next, then when that drops another 3 ppm unless nitrite does start to rise. If the ammonia is going straight to nitrate, that should make enough to show up on the nitrate test.

But if you do start to see nitrite, go with instructions as too much nitrite will stall the cycle.

Alkalinity is what water companies call KH. At over 100 ppm yours should be OK, you can always add a bit more bicarb if it does start to fall.

The chemical name of bicarb is sodium hydrogen carbonate, and the sodium bit is the problem when there are fish in the tank. Natural water sources don't have much sodium in them so fish have not evolved to cope with it, certainly not fish from soft water areas. We need another way to stop KH falling.

I have KH 3 german deg/54 ppm and I keep things stable by weekly water changes of at least 30% to top up the KH. I find this works fine for me.
Alternatives would be to use crushed aragonite in a bag in the filter - this contains both calcium and magnesium rather than crushed coral or limestone which only contain calcium. But if your pH is 7.0 or over, not much will dissolve. And it is possible to use too much.
Another option would be to use remineralisation salts designed for use with RO water. You wouldn't need much, just enough to boost your KH slightly. The downside to this is that you would have to add exactly the same amount per litre of new water at every water change as swinging GH would not be good for the fish. Doing emergency water changes if you were near the end of the pack of remin salts would be impossible;you'd have to keep an unopened pack in the cupboard at all times. And it would work out expensive long term.

I'd stick with water changes once you have fish and see if that is enough. You can always try one of the other options if water changes alone aren't enough.

Test done today. Ammonia seems around .25 to .50ppm, nitrites are o ( but could be down to using Tetra start Safe) and Nitrate seems to be about 5ppm, which is slightly up. Picture attached.

Hi Sue, just 1ppm to start. Light wise is either daylight or halogen. The Ammonia green is always hard to read as there seems to be subtle changes in the colour and always hard to discern.

To compare the test tube to the chart, place the tube against a white area on the chart and hold it up so you are looking straight through the side of the tube. Have the light source behind you shining over your shoulder.

You are looking for the shade of green (in the case of the ammonia tester) rather than the intensity of the colour. A chemistry lecturer at university once told us that the human eye is a pretty good judge of wavelength (ie the shade of the colour) but a poor judge of the colour's intensity.

@barneyadi I did notice one thing with the test samples you have shown. The water miniscus in some is still below the mark even after you added the drops so the result will be too 'consentrate' in some by perhaps 10%. I don't know if this will equate to a 10% reading error as I don't understand the chemistry behind the tests but it certainly won't help the accuracy.
I also know that the tubes themselves are not particularly accurate and trying to pour water out of a test tube and hit the mark isn't particularly easy either, and the line is quite thick..... I gave up with this method and use a 5ml syringe to squirt water in it's much easier, accurate and more consistent. Have a word with your local Nurse Gladice Emmanuel and see if she will let you have one.
Another trick I have suggested before is to get an image of the test strip on a tablet or phone and use the clean white background of the image to light the sample from behind You will also note that the reading card colours vary themselves so can images you can find on the Internet that were based on pictures so be sure to pick a good one.

Anybody,
I have seen this same type of question a couple of times, do you think a sticky post with images explaining would be useful? Don't worry I will keep the photometers method out of it

Well with nothing happening was going to start a fish in cycle, but have decided to give it one last chance. Have redirected the airflow to maybe get more oxygen in tank, plastic plants are swaying so there is a difference. Been out today and purchased some different ammonia from Homebase, 9.5% to see if that will help. So will let you know what happens.

Does anyone think a lack of oxygen might have stalled my cycle?. Have turned filter tube straight up towards surface now and surface is bubbling and rippling. Could an airstone or bubble bar help as well?

 not looking good, 24 hours after adding ammonia and no drop at all. Will give some more time and see what happens, but looking likely I will have to try a fish in cycle.