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Ph profile, co2 and 0kh

plantnoobdude

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Hi, in my high tech 60p I maintain soft water with 0kh and also inject co2.

Though 1.0ph drop is generally regarded as optimal and safe for live stock, does this still apply for tanks with no kh? I recently checked my tank pH and degas pH.

24h Degas sample is 6.65-6.7
Tank values stay from
5.2-5.3 throughout the day so far.
This means I have a ph drop of 1.4!!!

I was wondering, since I don’t have any buffer, is it possible I have less co2 in terms of ppm in the water, compared to say a tank with a kh of 4 with the same pH drop?

While my stock seem completely happy, I am a bit on edge.

Thanks!
 

Zeus.

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I use to run my 500l tank with a 1.4pH drop. But I wouldn't recommended it as there is a fine line between fish fine and opps
Lets assume the pH meters reading is correct, what colour is your DC m8 - mine was nearly clear at times
 

plantnoobdude

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I use to run my 500l tank with a 1.4pH drop. But I wouldn't recommended it as there is a fine line between fish fine and opps
Lets assume the pH meters reading is correct, what colour is your DC m8 - mine was nearly clear at times
What was the kh of the tank? My fish seem quite at home and readily accept food and engage in regular behaviours through out the photoperiod.
CC321B61-7DBD-40B7-A632-F23206101737.jpeg

Here is the dc colour, not yellow. 7 hours into photo period.
Lets assume the pH meters reading is correct,
it is a Hanna ph meter. That has been calibrated and stays within 0.03-0.04 pH of calibration solutions.
 

plantnoobdude

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Here is the general layout of the tank, co2 is provided via an inline diffuser.
061C1176-003D-40EA-B89E-EEF9E9FA8D33.jpeg
 

Zeus.

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I would trust the DC colour change as that is independent of kH and pH reading issues.
I think there also may be issues getting a correct pH reading when the kH is zero. I am not a chemist, but water can be tricky at times.
 

John q

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Though 1.0ph drop is generally regarded as optimal and safe for live stock, does this still apply for tanks with no kh?

Lets assume the pH meters reading is correct, what colour is your DC m8 - mine was nearly clear at times
I reckon with low kh the ph drop is irrelevant, although I agree for safety reasons its always wise to go with a 1 point drop.
My degassed water sits at 7.3, tank water never goes above 7. When the lights come on Co2 drops ph to 6.1, so a 1.2 drop. DC goes from @plantnoobdude green before Co2 comes on to a lime green/yellow at 6.1.

I'm paranoid about the dc colour and fish health, however I had a fault with solenoid timer a few weeks ago and Co2 stayed on all night, ph dropped to 5.8 and dc went yellow/clear, fish were completely fine, that's a 1.5 ph drop from degassed, assuming ph meter is correct.

What do we learn from this... low kh water behavior is difficult to predict.
 

jaypeecee

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Tank values stay from
5.2-5.3 throughout the day so far.

Hi @plantnoobdude

Your pH is very low. Nitrifying bacteria may struggle at such a low pH. I can't determine what livestock you have in the tank. Please clarify. I have a couple of other observations...

Although your DC is green, it's a rather odd green. And the entrance to your DC seems to be partially blocked by 'froth', particles and bubbles. This may be affecting the DC colour.

Finally, your filter inlet seems to be partially blocked by plant fragments. This may be interfering with water flow throughout the tank.

Oh, one more question - what is your water GH?

That'll do for now.

JPC
 

plantnoobdude

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Hi @plantnoobdude

Your pH is very low. Nitrifying bacteria may struggle at such a low pH. I can't determine what livestock you have in the tank. Please clarify. I have a couple of other observations...

Although your DC is green, it's a rather odd green. And the entrance to your DC seems to be partially blocked by 'froth', particles and bubbles. This may be affecting the DC colour.

Finally, your filter inlet seems to be partially blocked by plant fragments. This may be interfering with water flow throughout the tank.

Oh, one more question - what is your water GH?

That'll do for now.

JPC
1. Indeed it is quite Low, though I doubt it is a problem. Stock is ember tetra and a honey gourami.

2. I have cleaned the dc and added a fresh batch of 4dkh water and bromothymol blue. Will report back in a few days.

3. I doubt it, the flow is very strong around the tank and no dead spots can be seen.

4. My gh is about 4 though I have had it as Low as 1.5 gh.
 

plantnoobdude

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I would trust the DC colour change as that is independent of kH and pH reading issues.
I think there also may be issues getting a correct pH reading when the kH is zero. I am not a chemist, but water can be tricky at times.
Ok, i will use the ph meter as a view of the co2 stability for now, and the drop checker to guesstimate the concentration.
 

Yugang

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Ok, i will use the ph meter as a view of the co2 stability for now, and the drop checker to guesstimate the concentration.
Using a pH probe at 0 kH is not without risks #2 as the logarithmic relationship between CO2 and pH is no longer valid (pH can go anywhere depending in water chemistry) as kH approaches 0. As said, best is using drop checker, as that is independant of tank water. Take any pH probe reading with a grain of salt. For just a check on stability seems that not much can go wrong.

Note: I am also at pH drops around 1.4, and livestock is perfectly fine with that. It does depend on the tank and especially O2.
 
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_Maq_

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Though 1.0ph drop is generally regarded as optimal and safe for live stock, does this still apply for tanks with no kh?
You need much more CO2 to reach 1 degree pH drop in water with higher alkalinity. And vice versa - just a few of CO2 injected is enough for the same pH drop in water with very low alkalinity. Therefore, 1.0 pH drop is perfectly safe in your tank. You're not overdosing CO2, rather the contrary.
(In fact, 0.0000 dKH is impossible as long as there's any CO2 present because it will always partly turn into bicarbonate as long as pH value is above 4.5.)
Your pH is very low. Nitrifying bacteria may struggle at such a low pH.
Yes, but it hardly matters because ammonia (NH3) will almost 100 per cent react with water creating harmless ammonium (NH4+). Still, my experience suggests nitrifying microbes function very well at pH above 6.0, and with diminished effectiveness even at pH around 5.5.
Using a pH probe at 0 kH is not without risks
Wrong. It does not depend on (bi)carbonate content but electric conductivity of water, in other words on general mineralization. Reading of pH gets difficult at conductivity lower than approx. 30 µS/cm. Your tank water is obviously far above this limit.

I've got quite rich experience with sparingly mineralized water. There are processes in any tank which may push pH both up and down. Sometimes I get quite perplexed about them.
Two situations seem to be particularly dangerous/unpredictable: young (non-matured) tanks and soil substrates.
I find this situation rather tricky. In my country, those who inject CO2 usually control dosing by pH (pH is the constant). But in this community, it is often stressed that amount of CO2 should be held constant. I don't know how your CO2 system works, and I've got no experience with CO2 injection, anyway.
 

plantnoobdude

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Using a pH probe at 0 kH is not without risks #2
I’m going to be honest, that is a very old post ( almost 20 years now) and I doubt Barr still agrees with what he posted now.
Especially this part.
The system will crash, it might not have done this yet for you, but you'll get burned at some point. And have dead fish.”
Take any pH probe reading with a grain of salt. For just a check on stability seems that not much can go wrong.
alright, I do calibrate it and it does to produce fairly accurate results though.
Note: I am also at pH drops around 1.4, and livestock is perfectly fine with that. It does depend on the tank and especially O2.
what is your kh? If you have a kh higher than mine and have the same pH drop I will be sure my fish are fine.
 

plantnoobdude

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30 µS/cm. Your tank water is obviously far above this limit.
I’m guessing that would be tds of 15 if you use a tds-500 scale.
Yes, but it hardly matters because ammonia (NH3) will almost 100 per cent react with water creating harmless ammonium (NH4+). Still, my experience suggests nitrifying microbes function very well at pH above 6.0, and with diminished effectiveness even at pH around 5.5.
Yes I agree, I even fertilize with ammonium nitrate and fish see no issues, if the tank were to have say a pHof 8. I’m sure they’d be less than happy….

I don't know how your CO2 system works, an
To clarify for everyone in this thread.
The co2 system is as follows;
Co2 supermarket dual stage reg with solenoid
Camozzi needle valve
Bubble counter
Qanvee co2 inline diffuser
Co2 drop checker.
You need much more CO2 to reach 1 degree pH drop in water with higher alkalinity. And vice versa - just a few of CO2 injected is enough for the same pH drop in water with very low alkalinity. Therefore, 1.0 pH drop is perfectly safe in your tank. You're not overdosing CO2, rather the contrary.
This is comforting😊

I guess I just have the tendency to over think things…. Green drop checker, stable pH throughout photo period and happy fishies and I should stop fretting about minor details.
 

Yugang

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I’m going to be honest, that is a very old post ( almost 20 years now) and I doubt Barr still agrees with what he posted now
I am not a chemist, but I doubt if insights on water chemistry, buffers and pH change a lot over time. It is true, we don't see many reporting on pH crashes in reality, but my guess is that some caution (that's why I said depends on tank chemistry) at 0 kH is appropriate. As I am around KH 2 (depending on season and sourcing of water) I am no where near the point where the discussion would be relevant for my tank :)
 

Yugang

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You need much more CO2 to reach 1 degree pH drop in water with higher alkalinity.
This confuses me @_Maq_ . The famous KH/pH table is a log table, where every 0.1 pH corresponds roughly to a 25% change in CO2 ppm. 1 pH drop is roughly a 10 times increase of the CO2 ppm, irrespective of the KH. So if we assume that we start at about 3 ppm CO2 outgassed, a 1 pH drop will bring us to 30 ppm at any KH.

Where do I miss your point?
 

_Maq_

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Where do I miss your point?
If you inject CO2, a part of it will always react to produce HCO3-. The more so if your pH is higher. --> With higher alkalinity, it's more difficult to push pH down, be it CO2 or any other source of acidity (strong acid). Therefore, higher share will turn to HCO3-.
In ours, people tend to say that if alkalinity is higher than 5 °dKH, then injecting CO2 has hardly any effect. Obviously, this is not my personal experience.
if we assume that we start at about 3 ppm CO2 outgassed, a 1 pH drop will bring us to 30 ppm at any KH
Your assumption that 3 ppm is a fixed level is wrong. Yes, a 1 pH drop means tenfold increase in CO2 concentration, but the starting concentration of CO2 depends on biotic factors and initial alkalinity.
An example: a pH drop from 7 to 6 - if initial alkalinity is 4 °dKH, it means increase from 14 to 140 mg/L CO2. If initial alkalinity is 0.4 °dKH, it means increase from 1.4 to 14 mg/L CO2.
 

Yugang

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An example: a pH drop from 7 to 6 - if initial alkalinity is 4 °dKH, it means increase from 14 to 140 mg/L CO2. If initial alkalinity is 0.4 °dKH, it means increase from 1.4 to 14 mg/L CO2.
Fair, but perhaps we should keep the discussion practical.
When we mention pH drop in our hobby we usually mean with that 'pH drop as compared to outgassed aquarium water'. And, without overcomplicating things, this is not really KH dependent and usually a good practical approach. We're not doing a PhD thesis here.

Wrong. It does not depend on (bi)carbonate content but electric conductivity of water, in other words on general mineralization. Reading of pH gets difficult at conductivity lower than approx. 30 µS/cm. Your tank water is obviously far above this limit.
If you would have quoted my full sentence, the argument would be entirely different. I am not referring to the workings of a pH probe. The point is that several credible refences caution (I use a carefully chosen word here) about pH in water at 0 KH, and stress that the entire chemistry of the tank may lead to unexpected pH readings.
 
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