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Spray Bar and CO2 Diffuser placement confusion

ceg4048

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I think I have a decent flow as I can see that the leaves are gently swaying. The spray bar runs accross the tank and has 6 holes roughly 1/8" diameter. Is there a way to test if the flow is a complete circular motion by adding something to the tank?
Hi Monis,
Yes, you can cut a tiny piece of paper, perhaps pin-head size, and drop it on the surface, then watch it's path through the water. This will show you the general flow field that the spraybars create. Do this at as many locations as you want along the length of the tank (middle, corners and so forth). What you hope to see is that the paper heads toward the front glass hand heads rapidly downward along that front pane, then it should head towards the rear and then up along the rear pane. Of course, the speed will peter out and it may start to drift away from this ideal path, but you'd like to see it last at least half way towards the rear.

In this way you will be able to visualize the flow. This technique is not dissimilar to what is done in a wind tunnels using smoke to visualize air flow around an object such as an automobile or airplane.
following was the pH profile measured by API Drop Test Kit:
I highly recommend to anyone injecting CO2 to invest in a quality pH probe and pH probe calibration solution. It never ceases to amaze me how many posts I see where the hobbyists is giddy at the thought of spending megabucks on some fancy high powered light (which ironically is the root of all evil) and yet never give a thought to spending money on a good pH probe. Your money should always be spent first and foremost on CO2 problem solving because about 95% of all problems in a CO2 injected tank is due to poor CO2. Let that sink in for a moment... CO2 is always problematic and even if it's perfect today it's a sure thing that it will be somewhere between imperfect and catastrophic a month from now. I suggest investing in any of Hanna's multi-probe such as their pH/TDS/Temp probe.
It's difficult to comment on the yellow DC as there are so many factors such as what kind of water is placed in the DC, accuracy of the reagent and so forth.

Cheers,
 

erwin123

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From another thread, I thought the 1 pH drop is the drop from the gassed out pH, not from the pH just before CO2 switches on?
 

SudhirR

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From another thread, I thought the 1 pH drop is the drop from the gassed out pH, not from the pH just before CO2 switches on?

Both fully degassed pH and the pH at co2 injection on should remain the same. Are you noticing a marked difference?


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erwin123

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Both fully degassed pH and the pH at co2 injection on should remain the same. Are you noticing a marked difference?


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Hi Yes there is a difference for my tank water.

Like Katie in the other thread who has a 0.4 difference, I have a 0.5 difference between degassed pH and pH just before CO2 turns on. I don't need to wait 24 hours for it to show a difference- waiting 12 hours I already have a 0.5pH difference.

So I'm following the discussion on what would be the correct target pH to learn more.

I'm using an Apera Ph20 meter which is calibrated to a 4.0/7.0 solution.
 

aquascape1987

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Both fully degassed pH and the pH at co2 injection on should remain the same. Are you noticing a marked difference?

I don’t think that this is very common is it? I have never experienced this in any of my own tanks ever, since starting to inject CO2. There is always some residual CO2 left in the water from injection the previous day, by the time the CO2 comes back on again in my experience, so there would always be some Co2 to off gas to get your starting pH.
 

ceg4048

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Like Katie in the other thread who has a 0.4 difference, I have a 0.5 difference between degassed pH and pH just before CO2 turns on. I don't need to wait 24 hours for it to show a difference- waiting 12 hours I already have a 0.5pH difference.

So I'm following the discussion on what would be the correct target pH to learn more.
Both fully degassed pH and the pH at co2 injection on should remain the same. Are you noticing a marked difference?
I don’t think that this is very common is it? I have never experienced this in any of my own tanks ever, since starting to inject CO2. There is always some residual CO2 left in the water from injection the previous day, by the time the CO2 comes back on again in my experience, so there would always be some Co2 to off gas to get your starting pH.

That is correct. There is always some residual CO2 left in the water, however, the amount of residual is dependent on water temperature, whether the tank is top is closed or open as well as the degree of surface agitation. Also consider the accuracy and calibration quality of the device being used to measure the pH. This is normal and is not cause for concern. You can either use the reading you get from the residual CO2 or you can use the natural pH of the water as a reference. Whichever works for you will suffice. The 1 Ph drop is just a rule of thumb not some kind of cliff that your tank will fall off of if violated.
Some folks are rightfully concerned that using the residual reading may harm the fish so it is safer to use the natural pH as a reference for the drop. This is sound reasoning, especially for the inexperienced. Others use the residual reading and are fine. Fish can adapt to surprising levels of hypercapnia, within limits, and as long as it is done gradually.
More important than the number used as a reference is that your distribution is excellent. When this is achieved you'll find that you can lower the injection rate and still obtain a good pH drop and good, even CO2 levels throughout the tank.

This highlights yet another complicated nuance of CO2 technique. Obviously, if the injection rate is excessive during the day this is a problem, and blood CO2 levels acidify the blood and thus reduces the capacity of hemoglobin (in fish) and Hemocyanin (in inverts) to hold on to oxygen molecules. Fish and inverts however have a defense mechanism against blood acidifcation and that is their bodies release bicarbonate into the bloodstream to buffer the blood against internal pH depression. Additionally, during the photoperiod the plants release oxygen into the water column. The most dangerous time is early in the morning before lights ON, when the oxygen level is depleted and the plants and bacteria compete with the fish for oxygen. So the combination of elevated CO2 and low oxygen is less than ideal. That is why some folks employ air-stones at night to reduce CO2 levels and to help with oxygen. This is a Catch-22 however because the gas injection rate must now be high enough to compensate for the purged residual CO2.

Cheers,
 

SudhirR

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I don’t think that this is very common is it? I have never experienced this in any of my own tanks ever, since starting to inject CO2. There is always some residual CO2 left in the water from injection the previous day, by the time the CO2 comes back on again in my experience, so there would always be some Co2 to off gas to get your starting pH.

My co2 goes off at 5 pm and my aeration comes on. And the pH goes up till about midnight or so and remains almost constant till 11 am when the aeration stops and the co2 turns on.

My co2 chart is here: CO2 Already Dialled In, But Rechecking

Also I have good amount of surface agitation and flow in my tank. Now I am confused as to at what point the degassed pH needs to be measured. I was thinking it’s at the point when all the co2 is degassed and the PH is fairly constant. Pls let me know the correct interpretation.


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aquascape1987

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I was thinking it’s at the point when all the co2 is degassed and the PH is fairly constant. Pls let me know the correct interpretation.
I think that is the correct starting point. Just that most folks need to let their water de gas/actively de gas their water to be able to get this pH measurement.
 

erwin123

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Amazon productI'm using a budget Apera pH meter. Hey, it got 3370 reviews in Amazon. When I first got it and put it into the calibration solution, it was only 0.1 off from the reference solutions.

Amazon productHere's the more expensive multi-test.
 

arcturus

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Would this pH meter from Hanna suffice : Hanna HI-98100 Checker plus pH tester
Seens these products are pretty expensive :D

Most of them usually suffice for a (short) while. Low quality devices tend to have low quality probes that require frequent calibration. The probe will eventually start giving erroneous readings. Better to invest on a device with a replaceable probe (such as the GHM Greisinger 609850 or a better device). When the probe fails, then invest on a good quality probe since it will last longer and you will end up saving money in the long run. But it makes absolutely no sense to put a lot of money on a high-tech setup with CO2 injection and then trying to save money buying a low-tech device that does not enable you to properly measure CO2...
 

ceg4048

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Would this pH meter from Hanna suffice : Hanna HI-98100 Checker plus pH tester
Seens these products are pretty expensive :D
Hi Monis,
Wow, I'm really shocked at the pricing although I'm not familiar with the Danish Krone. According to the currency conversion charts that is about $65 in US currency, whereas in USA that same probe retails for about $40. So that is not too bad for a probe with two point calibration and with a replaceable probe. These are the two most important features and is definitely better than reagent based test kits. My choice would be for the HI-98108, shown just to the right on that page, but that cost 574 Krone. Again, compare how much money people are willing to spend for fancy lights.
Also I have good amount of surface agitation and flow in my tank. Now I am confused as to at what point the degassed pH needs to be measured. I was thinking it’s at the point when all the co2 is degassed and the PH is fairly constant. Pls let me know the correct interpretation
Hi, you are over-thinking this problem. As mentioned, the natural pH of your water should be the starting point. All you have to do is take a sample in a bottle and shake it up for 5 minutes or so, or let it sit on the counter for an hour. Whatever pH is measured is a good starting point. Subtract 1 and there is your target. Keep it simple. You can always make adjustments from there and as your plants grow in you very well may need to adjust the target downward - but look at your plants. Are they healthy and algae free? Are the fish healthy? Ultimately, those are the only parameters you need to worry about.

Do not fret over what number to use. In fact, people using ridiculous amounts of lighting often require a much larger pH drop to avoid algal blooms.

Here is an example of my tank using absurdly high lighting. In my case hair algae was a constant companion, even with good flow/distribution, so it was necessary to use a higher injection rate if I didn't want to reduce the lighting. Over a period of a few weeks I was able to drop the pH by a full 2 units from the natural pH of the tank . This was accomplished slowly and carefully while observing the fish. Again, when done deliberately and carefully the fish are resilient and easily adapt. The CO2 was on for only 4-5 hours and that allowed the fish to recover.
8395165784_b0282135c1_c.jpg


So there is a wide margin if your distribution is adequate. Folks often have difficulty with their fish adapting to CO2 because of poor flow /distribution, so concentrate on that, observe the tank and do not worry about which number to use,

Cheers,
 

MMonis

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Hi @ceg4048
I purchased the Hanna phep HI-98107 pH meter, as this was the only one available for delivery in Denmark at the earliest. Following is the pH profile I ran today:
TimepHRemarks
10:006.9CO2 turned on (same pH value before CO2 on as well)
11:006.31 hr after CO2 on
12:006.22 hrs after CO2 on
12:306.22.5 hrs after CO2 on
13:006.23 hrs after CO2 on
13:306.23.5 hrs after CO2 on
14:006.24 hrs after CO2 on; Lights on (sunrise start - sunrise period 30 mins)
14:306.24.5 hrs after CO2 on; 30 mins after Lights on (RGB - 40% intensity)
15:006.25 hrs after CO2 on, 1 hr after Lights on
15:306.2/6.35.5 hrs after CO2 on; 1.5 hrs after Lights on
16:006.2/6.36 hrs after CO2 on, 2 hrs after Lights on
17:006.37 hrs after CO2 on; 3 hrs after Lights on
18:006.38 hrs after CO2 on; 4 hrs after Lights on
18:306.3CO2 off; 4.5 hrs after Lights on
19:006.430 mins after CO2 off; 5 hrs after Lights on
19:306.61 hr after CO2 off; 5.5 hrs after Lights on (sunset start - sunset period 30 mins)
20:006.71.5 hrs after CO2 off; Lights off
21:006.82.5 hrs after CO2 off; 1 hr after Lights off

I was expecting that around 13:00 pm I would get the pH drop by 1, but it never went down below 6.2 throughout. Since I have started this aquarium around 50 days ago and using Tropica Aquarium Soil, could the soil be preventing the pH from dropping lower than 6.2 ?
Any insights based on the pH profiling above ?

Regards,
Mel
 

ceg4048

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I was expecting that around 13:00 pm I would get the pH drop by 1, but it never went down below 6.2 throughout. Since I have started this aquarium around 50 days ago and using Tropica Aquarium Soil, could the soil be preventing the pH from dropping lower than 6.2 ?
Any insights based on the pH profiling above ?
Hi Mel,
OK, well, first of all, it's really important to understand the reason we are using a pH drop. I feel that a lot of folks don't understand why we do it. We just tell them they should do it, and they follow suit, not always understanding the mathematics of the method. As you probably know (or perhaps were told) if you measure the pH of the tank water and plug that reading into the infamous pH/KH/CO2 chart you will almost always get the wrong CO2 value because the tank water is affected not only by the Carbonic acid produced by the CO2, but the pH is driven even lower due to the organic acids present in the water. So folks who are unaware of this phenomenon will always read a higher CO2 value than there actually is in the water.

So we take a pH reading at the start and that gives us a pH value composed of a [pre-CO2 induced acidity + Organic acidity] then we take a reading later in the day to get a [Co2 induced acidity + Organic acidity].

When we say find the "pH drop" what we are really saying mathematically is to subtract the CO2 induced reading from the pre-CO2 induced. A geek would be write this as a simple equation:

[pre-CO2 induced acidity + Organic acidity] - [Co2 induced acidity + Organic acidity]

Which then becomes:
pre-CO2 induced acidity + Organic acidity - Co2 induced acidity - Organic acidity

The expression "Organic acidity" cancels because there is one with a plus (+) and one with a minus (-).
So the equation now reduces to:
pre-CO2 induced acidity - Co2 induced acidity
This is exactly what we are trying to do. Since BOTH pre and post CO2 reading are equally affected by the same organic acid, taking the DIFFERENCE between the two readings effectively eliminates the organic acid contribution from the equation. We can be confident that over the span of a few hours the organic acid content of the tank water will not appreciably change. We assume it will have the same value and therefore subtracting one pH reading from the other, even though we do not know exactly the quantity of the organic contribution, will cancel the organic acid content.

Now, in the ideal world we'd be able to go to the chart with your numbers:
pre-CO2 is 6.9 and post CO2 is 6.2
For any KH we would plug 6.9 in the chart and the chart would returns a fictitious CO2 value.
Then we would plug 6.2 in the chart and it would returns another fictitious CO2 value. Ideally, we would subtract one from the other and this would tell us our true CO2 value - except, now we get to the second problem with the pH/KH/CO2 chart. Not only does it assume that the acidity of the water is caused ONLY by CO2, but it also assumes the KH of the water is ONLY cause by carbonate. As we should know, our KH test kit is NOT a KH test kit. It is an ALKALINITY test kit and the reading it returns is actually due to many possible components not named carbonate or bicarbonate.

The third problem with the chart is that the data is not linear, it's logarithmic because pH itself is logarithmic. We've kind of figured out that a drop of about 1 unit will give you about 30-40ppm but these are just basic numbers. Everyone's alkalinity composition differs as does their tank acid contribution. This is why I'm always warning people to NOT get caught up in chasing numbers as if they were the Holy Grail. At best they are rules of thumb. You still have to monitor your fish and plants.

This was a really long winded way of saying "No it has nothing to do with you're soil and everything to do with your injection rate and flow/distribution. In any case, just live with your 6.2 for the moment and when you have a lot of time to experiment with the injection rate and are able to monitor your fish make the adjustments as needed. If your plants are happy with this configuration then leave it be. If you are experiencing CO2 related algae or CO2 related faults then you might want to think about trying to optimize further. Having said that, it should not take 4 hours to drop the pH 0.7 units and as I mentioned, that is most likely due to some combination of injection rate, diffusion method, excessive surface agitation and flow/distribution.

Continue to monitor with your new probe. Keep the tip moistened and calibrate frequently. Every time you make a change to your setup repeat the exercise and record the data so that you can analyze at a later date. Avoid the pH/KH/CO2 charts as if it were the plague.

Cheers,
 

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