Sudden nitrite drop

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Darter217

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My nitrite has dropped to zero 7 days after my second dose of ammonia but my ammonia is still reading at 3ppm. Is that normal or has my cycle crashed?
 
That does sound a bit odd.
Did the nitrite drop to zero from a high level all at once or did it slowly go down to zero? And which tester are you using?
 
That does sound a bit odd.
Did the nitrite drop to zero from a high level all at once or did it slowly go down to zero? And which tester are you using?


Nitrite was around 2ppm 2 days ago so that was a very sudden drop. I'm using the API freshwater test kit.
 
I've looked at my cycling record from a few years ago and mine dropped from over 5 to zero between day 40 and day 42 (testing every second day), but my ammonia had been zero since day 28. So nitrite can drop to zero suddenly but it's the ammonia reading that is puzzling.

Have you checked your pH? In Scotland you will most likely have very soft water and if the pH had dropped very low it will affect the bacteria.
 
I've looked at my cycling record from a few years ago and mine dropped from over 5 to zero between day 40 and day 42 (testing every second day), but my ammonia had been zero since day 28. So nitrite can drop to zero suddenly but it's the ammonia reading that is puzzling.

Have you checked your pH? In Scotland you will most likely have very soft water and if the pH had dropped very low it will affect the bacteria.


During the first stage of the cycle my ammonia was pretty slow to come down so in guessing it'll be the same during the second stage. Also because it was at 4ppm instead of 3 but for the second dose I manages to get it down to 3ppm.

I've monitored my PH every now and again and it's stayed consistent at 6.8 so I don't think that's too much of an issue. During the first stage of my cycle the nitrite rose way before the ammonia dropped enough to add the second dose.
 
That pH shouldn't have stopped the bacteria, but it is quite low for cycling - near 8 is the optimum for bacteria growth. It does mean that your cycle will be slower than one in a hard water area though.
Keep an eye on the pH, and give it a few more days.
 
That pH shouldn't have stopped the bacteria, but it is quite low for cycling - near 8 is the optimum for bacteria growth. It does mean that your cycle will be slower than one in a hard water area though.
Keep an eye on the pH, and give it a few more days.


I will do, I think my cycle is just slower then average as the first phase took quite a while too. So I'll just give it time.
 
That pH shouldn't have stopped the bacteria, but it is quite low for cycling - near 8 is the optimum for bacteria growth. It does mean that your cycle will be slower than one in a hard water area though.
Keep an eye on the pH, and give it a few more days.


Tested today and my PH has crashed right down to 6.0 so I'll need to find out why that happened?
 
It's because you have very soft water so you also have low KH. Nitrite is acidic and KH stops the pH dropping but when there is very little KH, it gets used up then there's nothing to stop the pH falling.

There is something you can do just for during cycling. Add bicarbonate of soda. This will add KH to the tank. But it will also add sodium which is not good when there are fish in the tank so once the tank is cycled you'll need to drain the tank down to the substrate to remove it. You may already have some bicarbonate of soda in the kitchen; if not it's in the home baking section of the supermarket.
Use 1 x 5 ml spoonful for every 50 litres tank water. Take a bit of water out of the tank, dissolve the bicarb in that then pour it back into the tank. Wait half an hour then test pH again - it should have gone up. Test pH every time you test the rest to keep an eye on it.


At the end, once you've done the huge water change and got fish you'll be doing weekly water changes of over 50% and this will replenish KH. But with your soft water you need to keep soft water fish so even if the pH drops with fish in the tank the fish will be fine.
 
It's because you have very soft water so you also have low KH. Nitrite is acidic and KH stops the pH dropping but when there is very little KH, it gets used up then there's nothing to stop the pH falling.

There is something you can do just for during cycling. Add bicarbonate of soda. This will add KH to the tank. But it will also add sodium which is not good when there are fish in the tank so once the tank is cycled you'll need to drain the tank down to the substrate to remove it. You may already have some bicarbonate of soda in the kitchen; if not it's in the home baking section of the supermarket.
Use 1 x 5 ml spoonful for every 50 litres tank water. Take a bit of water out of the tank, dissolve the bicarb in that then pour it back into the tank. Wait half an hour then test pH again - it should have gone up. Test pH every time you test the rest to keep an eye on it.


At the end, once you've done the huge water change and got fish you'll be doing weekly water changes of over 50% and this will replenish KH. But with your soft water you need to keep soft water fish so even if the pH drops with fish in the tank the fish will be fine.


I don't have any at the moment but I'm going out in the morning to get some. Thanks for the advice.
 
It's because you have very soft water so you also have low KH. Nitrite is acidic and KH stops the pH dropping but when there is very little KH, it gets used up then there's nothing to stop the pH falling.

There is something you can do just for during cycling. Add bicarbonate of soda. This will add KH to the tank. But it will also add sodium which is not good when there are fish in the tank so once the tank is cycled you'll need to drain the tank down to the substrate to remove it. You may already have some bicarbonate of soda in the kitchen; if not it's in the home baking section of the supermarket.
Use 1 x 5 ml spoonful for every 50 litres tank water. Take a bit of water out of the tank, dissolve the bicarb in that then pour it back into the tank. Wait half an hour then test pH again - it should have gone up. Test pH every time you test the rest to keep an eye on it.


At the end, once you've done the huge water change and got fish you'll be doing weekly water changes of over 50% and this will replenish KH. But with your soft water you need to keep soft water fish so even if the pH drops with fish in the tank the fish will be fine.


Do you have any other ideas about the nitrite dropping to zero and the ammonia staying high? I just want to know if I can continue my cycle after adding the baking soda without starting again.
 
I would add the bicarb and see what happens over the next couple of days. I know that a very low pH stops bacteria multiplying, but I don't know if that is both bacteria or just one of them. It is possible that low pH affects the ammonia eaters more than the nitrite eaters. Increasing pH by adding bicarb will hopefully allow the ammonia eaters to start again. If it doesn't we'll need to think of something else.
The worst that will happen is that you'll have to drain the tank and refill it, adding bicarb, then dose 3 ppm ammonia and go from there.
 
I would add the bicarb and see what happens over the next couple of days. I know that a very low pH stops bacteria multiplying, but I don't know if that is both bacteria or just one of them. It is possible that low pH affects the ammonia eaters more than the nitrite eaters. Increasing pH by adding bicarb will hopefully allow the ammonia eaters to start again. If it doesn't we'll need to think of something else.
The worst that will happen is that you'll have to drain the tank and refill it, adding bicarb, then dose 3 ppm ammonia and go from there.


I added it today and the PH is now reading at 7.2, I'm also due to test ammonia and nitrite tomorrow. I'll give it a few days but are you okay for me to come back to you on this thread if the problem persists?
 
Yes, post as many questions as you need to :)


My tap water KH is 3 dH and when I did my first fishless cycle years ago using the old "add ammonia every time it drops to zero" method (which makes a lot of nitrite) I too had a pH crash. Bicarb solved the problem. So when I did another a few years later to see how the new method on here works, I added bicarb at the start and had no problems.
 
Yes, post as many questions as you need to :)


My tap water KH is 3 dH and when I did my first fishless cycle years ago using the old "add ammonia every time it drops to zero" method (which makes a lot of nitrite) I too had a pH crash. Bicarb solved the problem. So when I did another a few years later to see how the new method on here works, I added bicarb at the start and had no problems.


Thanks for the help mate. Im going to test ammonia today, won't bother with nitrite as it's gone down to zero and the first snack dose (dose 3) is meant to be added when ammonia drops to zero. I'll come back to you if things don't improve soon.
 

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