Cycling & PH Help

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Robbo80

Aquarium Advice Apprentice
Joined
Apr 2, 2025
Messages
22
Location
Uk
Hi guys, just after a bit of advice. I've just set up my aquarium and started the cycling process. I'm currently on day 5. I'm a bit worried about low PH and my cycle stalling. I live in a soft water area.

My results so far are

DAY 1 (Before Ammonia)
PH=7.8
AMMONIA=0
NITRITE=0
NITRATE=0
AMMONIA ADDED

DAY 2
PH=7.8
AMMONIA=2.0ppm
NITRITE=0
NITRATE=5.0ppm

DAY 3
PH=7.2
AMMONIA=1.0ppm
NITRITE=0.25ppm
NITRATE=5.0ppm

Ammonia added after test

DAY 4
PH=7
AMMONIA=2.0
NITRITE=0.50
NITRATE=5.0

Day 5 Results
PH 7
Ammonia=2.0ppm
Nitrite=1.0ppm
Nitrate=10ppm

Just for reference I am using Dr Tims Ammonia and FritzZyme TurboStart 700 and my tank is 240 litres (I think about 55 gallons US)

It was a bit tricky to read today's (day 5) results. PH is still either at 7 or just coming to 6.8, it was really hard to tell.

Interesting to me is the Ammonia was difficult to read, at the very least it's not changed from yesterday at 2.0ppm but it could have even rose a little to 4.0ppm. It was very hard to tell matching the chart colour. I expected the Ammonia to drop as before. It went down from 2.0ppm to 1.0ppm the day after adding Ammonia last time.

I purchased a API GH & KH test kit and my tap water i think is reading at 0 KH (test went straight to yellow with no blue) and GH is 5 = 89.5.

Looking at my results do you think my cycle will stall? I'm seriously thinking of getting some crushed coral, but then I hear other people say to use something like baking soda. I don't like the idea of constantly having to add chemicals. There is a vast wealth of information but some of it is contradictory.

Should I do a 30% water change to try and keep PH up tomorrow?

Any help or advice is most welcomed. I'm a relative novice to fish and aquariums, I'm trying to research and gain knowledge but need a bit of a nudge.

Many thanks
 
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If your KH is zero, then your aquarium won't cycle. The process that turns ammonia to nitrite to nitrate uses up KH and once it's gone the nitrogen cycle stops functioning. There is some conversation that maybe in low pH, KH environments that the nitrogen cycle gets its carbon from other sources like disolved CO2, but if this is the case it's much slower to establish.

Your profile says you are UK based, so its not likely your KH is zero, but it could be low, particularly if you are north west, south west Scotland or Wales. You should be able to get your tap water parameters from your water company, which will be more accurate than any test.

It's a bit weird that your KH is low, but pH is high. Low KH usually causes low pH, so that's something worth double checking with your water company.

Low KH will get used up pretty quickly, so your cycle may start, then stop again until KH is replenished with a water change, then start to establish again. But never really get going. It takes about 7ppm of KH to cycle out 1ppm of ammonia, so if you have say 1 degree of KH (18ppm), that would get used up by cycling out about 2.5ppm of ammonia. While doing a fishless cycle you are dosing far more ammonia than a tank full of fish will produce, so the KH gets depleted much quicker while cycling than it does during normal operation. It may be that once you are actually cycled you can keep the KH positive just by regular water changes, but that really depends on how low your KH is and how heavily stocked your aquarium is.

IMO you have a couple of options.

You can forget about cycling altogether. Let the KH deplete, which will lower your pH. The nitrogen cycle will stop functioning, but at pH below 7 your ammonia is non toxic ammonium. Just let the ammonia build up between water changes, and keep fish that do well in acidic, soft water.

Or, address the low KH which will also stabilises the pH. Crushed coral will slowly disolve, raise your KH to some degree, stabilise your pH and keep your cycle functioning. Crushed coral will also raise general hardness (GH). Mixing baking soda in the water will similarly raise KH and stabilise pH, without affecting GH. Baking soda will add sodium into the water too, which isnt always a good idea if you want to keep fish that suit low disolved solids. Alkalinity Buffers will also raise KH without affecting GH.
 
If your KH is zero, then your aquarium won't cycle. The process that turns ammonia to nitrite to nitrate uses up KH and once it's gone the nitrogen cycle stops functioning. There is some conversation that maybe in low pH, KH environments that the nitrogen cycle gets its carbon from other sources like disolved CO2, but if this is the case it's much slower to establish.

Your profile says you are UK based, so its not likely your KH is zero, but it could be low, particularly if you are north west, south west Scotland or Wales. You should be able to get your tap water parameters from your water company, which will be more accurate than any test.

It's a bit weird that your KH is low, but pH is high. Low KH usually causes low pH, so that's something worth double checking with your water company.

Low KH will get used up pretty quickly, so your cycle may start, then stop again until KH is replenished with a water change, then start to establish again. But never really get going. It takes about 7ppm of KH to cycle out 1ppm of ammonia, so if you have say 1 degree of KH (18ppm), that would get used up by cycling out about 2.5ppm of ammonia. While doing a fishless cycle you are dosing far more ammonia than a tank full of fish will produce, so the KH gets depleted much quicker while cycling than it does during normal operation. It may be that once you are actually cycled you can keep the KH positive just by regular water changes, but that really depends on how low your KH is and how heavily stocked your aquarium is.

IMO you have a couple of options.

You can forget about cycling altogether. Let the KH deplete, which will lower your pH. The nitrogen cycle will stop functioning, but at pH below 7 your ammonia is non toxic ammonium. Just let the ammonia build up between water changes, and keep fish that do well in acidic, soft water.

Or, address the low KH which will also stabilises the pH. Crushed coral will slowly disolve, raise your KH to some degree, stabilise your pH and keep your cycle functioning. Crushed coral will also raise general hardness (GH). Mixing baking soda in the water will similarly raise KH and stabilise pH, without affecting GH. Baking soda will add sodium into the water too, which isnt always a good idea if you want to keep fish that suit low disolved solids. Alkalinity Buffers will also raise KH without affecting GH.


That's some excellent info thank you. I am from the UK in Birmingham but I believe the water is from Wales. I will give it some thought but leaning towards trying to carry on fishless cycling.

I might research to see if there are any fish that would thrive in my current parameters. Would be much easier i guess. I've got my heart set on some Pearl Gourami's so if they do okay it's a matter of finding other suitable community fish.
 
Severn Trent same as us? Yes their water into Birmingham is supplied from Wales, so it will be very soft and the pH is on the higher side. Must have some unusual mineral content to have low KH/ high pH. I'm not sure how that works.

A general figure from Severn Trent for KH in the Birmingham area is about 40ppm or just over 2 degrees. You can narrow that down to your postcode online yourself if you wish. Get the Hardness Clark figure and multiply by 14 to get KH roughly in ppm. Roughly 18ppm to 1 degree of KH, whichever is your preferred unit.

Regardless of actual number, that KH is low and will deplete quite quickly. If you are wanting to cycle the aquarium rather than just let everything get acidic, I would get that up higher. With the high pH, I'm not sure that crushed coral will actually disolve to any meaningful degree, you would have to give it a go and see what happens. You might find that as the KH depletes, and the pH drops, that the crushed coral balances everything out and keeps things stable. Would be interesting to know how things go.
 
So im on day 22 with my fishless cycling. I've managed to keep my PH levels at 7 or above. But im wondering how my cycle is actually going.

I've dosing upto 2.0 using Dr Tims Ammonia. My Ammonia levels go to 0 every morning when I do my checks. Nitrites are high, between 2 or 5, or even possibly higher. I find it hard to distinguish the purples. The strange bit is my Nitrates too. They remain quite lowish. I get the odd day when the test goes red and the highest ive had is 20ppm which was 2 days ago, but then they do drop back to what I see is 5ppm. I've added a picture of the last 10 days test results

Am I cycling OK? I do have some plants. Some Water Sprite, Frogbit (i think im going to have only this or water sprite not both), hygrophila polysperma, Java Fern, Anubias and some Moss balls. Could the plants be the reason for the low nitrate readings?

Many thanks.20250420_191451.jpg
 
Your low nitrate is more likely down to those nitrite to nitrate microbes not yet establishing. You are 3 weeks into what could easily be a 3 month process, and it's a bit early to see the nitrite turning into nitrate.

The nitrate you are seeing is more likely a false positive. Nitrite in the water causes a false positive in the nitrate test, or a higher positive test if there is both nitrite and nitrate present. I did find the specifics on this, but can't find it again, but like the ammonia test is a test for free ammonia and ammonium combined, the nitrate test is a test will show positive for both nitrite and nitrate ions with nitrite throwing off the test result. So its only when the aquarium is cycled, and the nitrite is zero that the nitrate test is useful. When there is nitrite in the water, put your nitrate test away as you can't rely on the result. It just confuses you when it doesn't do what you expect. Are you seeing lower nitrate when the nitrite reading is also lower?

It could be the plants, some of them will suck up a lot of nutrients, but my bet would be on your cycle not having established enough to start producing nitrate yet to any meaningful degree. If you are still seeing low nitrate when the nitrite is zero, that's when you can say they are eating up the nitrate.

I wouldn't worry about progress. You appear to be right where I would expect to be after 3 weeks.
 
My nitrites have been quite high for a while and I don't think they have dropped at all yet. As mentioned, I do struggle between the last 2 purples on the api test.

So you think im OK as I am. Carry on dosing upto 2ppm on the ammonia?
 
I think you are doing fine. The 2 options I would consider going forward.

1. Test daily and redose ammonia to 2ppm whenever it drops to zero. If the nitrite goes beyond your tests ability to read (5ppm using the API liquid drop test), change water to get it readable before you redose ammonia. This prevents nitrite getting so high you have no idea where it is.

2. Test daily and redose ammonia to 2ppm whenever ammonia and nitrite are zero.

Either way, when you can dose 2ppm and see ammonia and nitrite at zero 24 hours later you are cycled.

Ive done both in the past, #1 is the more common route because it keeps the ammonia to nitrite microbes fed and growing, but an advantage of doing #2 is you more clearly see what progress you are making with the nitrite to nitrate stage as you arent continually topping up ammonia and nitrite. If both ammonia and nitrite drops to zero in a week, then after redosing ammonia it then takes 5 days to drop to zero you can see the progress. Id be inclined to give #2 a try and see if the nitrite is dropping.

For info, every 1ppm of ammonia turns into 2.7ppm of nitrite and then 3.6ppm of nitrate (assuming nothing else is acting on the process, like your plants). So your daily 2ppm of ammonia should be increasing the nitrite by about 5.5ppm. After 2 days, you should have more than 10ppm of nitrite. If you don't, either the plants are consuming some of the ammonia before the nitrogen cycle can get to it, or some of the nitrite is going to nitrate. Or a bit of both.
 
That sounds like great advice. I do have a feeling that my nitrite levels are off the chart. I've been dosing virtually every day.
 
Id probably change water until you can get the nitrite to a testable level, then redose ammonia, then see where the ammonia and nitrite goes. You never know, if the nitrite is stupidly high it may already be dropping and you would have no way of knowing until it dropped enough to show on your test.
 
I'll help with a visual (y) This is the entire nitrite cycle in graph form. 1745182102385.jpeg As you can see, it takes longer for the nitrites to rise and fall as it does for the ammonia to do the same. Breaking that down, it means the microbe that that convert ammonia to nitrite grows faster than the microbe that converts nitrites to nitrate. As Aiken explained, with some test kits, you get a false nitrate reading when you have high nitrites so the way to know if you are getting a true reading is if the nitrates are rising while the nitrites are falling. So in a completely cycled tank, ammonia and nitrites are converted to nitrate in under 24 hours. Until then, you need to wait it out. The timing issue is going to be determined not only by the pH but the carbonate ( KH) present, temperature and phosphate level. Ideal parameters for optimal reproduction of the microbes are as follows: pH: 7.3-8.0, KH: greater than 80 PPM, Temp: 25-30 C and phosphate levels above 0. The only thing I know that will totally stop nitrification is the pH but anything above or below the other ideal parameters will just lengthen the time frame for completion.
Hope this helps. (y)
 
It does thank you very much. At this point I think im going to try patience and see what the numbers are over the next week. If there is no change or nitrite is still sky high ill probably do a significant water change.
 
It does thank you very much. At this point I think im going to try patience and see what the numbers are over the next week. If there is no change or nitrite is still sky high ill probably do a significant water change.
A couple of the challenges many face these days is that some water companies add nitrates to the tap water so it confuses people and they think it's coming from the tank and when you get false positive results for nitrates when the test is really picking up nitrites. :facepalm: So the key is rising nitrates not just the presence of nitrates. That's the sign the tank is cycled. (y)
 
Pretty chuffed this morning. Tested my water and the nitrite was looking lighter at around 0.50ppm. Nitrates are either 40 or 80ppm. Think I can stop panicking now. Thank you guys

1000009165.jpg
 
I carried on as normal with the dosing. I was going to give it a week as normal and then do a water change if nothing had changed, but it looks like nature is taking its course.
 
Wow so quick. A few more days of the same and its considered cycled right?

I know i need to do a water change before adding fish to get the nitrate down a bit. Im not in a position to start stocking until the end of the month. Would i keep dosing ammonia until i do the water change a day before adding fish?

1000009182.jpg
 
Yeah, if you keep zero ammonia + nitrite after adding ammonia for a few days then consider yourself cycled.

If you are talking a few days before you add fish, then it's going to be OK to stop adding ammonia, but longer than that I would keep dosing.

You want to get the nitrate down to maybe 10ppm before adding fish. Looking at your nitrate level that's going to be a near 100% water change. What you might be better off doing is a 50% water change every couple of days before dosing ammonia so it comes down gradually between now and when you get your fish. It will also confirm that a water change isn't going to effect your cycle. It shouldn't, but its worth checking since you have time. Good practice doing water changes without fish too.
 
I'm at the point now where i think I can add fish tomorrow. Ammonia and Nitrite both been coming back at 0 since the 23rd April. Did a 80-85% water change last night and after testing the water 30 minutes ago, my Nitataes are somewhere between 10-20ppm, though there is 5.0ppm in my tap water.

Should I add 1 final dose of ammonia, maybe half a dose today?
 
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