nutrient problem - The Planted Tank Forum
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post #1 of 18 (permalink) Old 04-03-2017, 12:17 AM Thread Starter
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nutrient problem

I am growing aquatic plants and they seem to be doing well, I have Anubius that flowers regularly. I feed then csm+b,K2SO4 and i use Osmocote plus diy tabs. My nitrate is good and my phosphate isgood. My KH is 3 and i add co2 to make PH 6.6. making my co2 level 22.5. I dont have much IF any pearling or O2 bubbles rising. When I do a water change of even 5 gallons on my 46 g tank the plants pearl and send trails of O2 to the top of the water. The flower on my anubius is even sending a trail of bubbles skyward. Even on my tanks without co2 injection the same thing happens. After adding tap water(well water) the PH stays at 6.6 so it doesn't seem to be an addition of co2 from it. I don't know what nutrient that my well water is supplying my plants. Any suggestions would help.
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post #2 of 18 (permalink) Old 04-03-2017, 12:26 AM
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After a water change, the "pearling" you are observing is not true pearling. Water from the tap typically has a lot of dissolved gases in it, which then will accumulate on leaves of plants and stream upwards (as the leaves serve as nucleation points for the dissolved gases)
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post #3 of 18 (permalink) Old 04-03-2017, 12:41 AM Thread Starter
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that i would understand as it sometimes is on the glass and things BUT my Anubias and other plants are sending up streams of O2 to thew surface. I mean a constant stream like a thread.

Bump: and i see namy sporatic bubbles coming from other plants from the same spot on the plants.

Bump: many*
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post #4 of 18 (permalink) Old 04-04-2017, 12:20 AM
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Quote:
Originally Posted by spidrman68 View Post
that i would understand as it sometimes is on the glass and things BUT my Anubias and other plants are sending up streams of O2 to thew surface. I mean a constant stream like a thread.

Bump: and i see namy sporatic bubbles coming from other plants from the same spot on the plants.

Bump: many*
This is either due to the excessive gas in the water escaping or injury to the plants, which would also allow gases to escape.

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post #5 of 18 (permalink) Old 04-04-2017, 03:30 PM
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Wink pH/kH Table

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Originally Posted by spidrman68 View Post
My KH is 3 and i add co2 to make PH 6.6. making my co2 level 22.5
Okay, please let me try and explain a couple things.
The pH/kH table as a way to measure your CO2 content, is at best, very imprecise, going in the direction of unreliabe. That table assumes you have water, some carbonates, co2, and nothing else, almost pure water. The table assumes that pH shifts are limited to CO2. 99% of the time, this is not the case. Changes to the pH by a bit of acidity completely throw the table off. I would have 100+ ppm of CO2, for example, which is just not true.

You could rest your water for some hours, or use an air stone, to find out your water pH when CO2 is in balance with the atmosphere. That DOES give you the pH drop.
The problem is with people saying 1 point pH drop equals 30ppm. That might be the case, might not. George Booth and his studies came up with this value of "minimal" CO2, which varied from 2 to 3ppm in a tank. This is water in a tank, with active fish and bacteria. If we consider this as a starting point, a 1 point pH drop would add 20 to 30ppm.

All gases will, given time, balance themselves between air/water, as explained by Henry's law (partial gas pressure, solubility, etc). So, given time, the roughly 400ppm of CO2 in the atmosphere will cause our water to have around 0.5ppm of CO2. Inside our homes this initial co2 value would go even higher (e.g. 1000ppm), which again would put more CO2 into the water.
Water, resting outside the tank, is getting its CO2 exclusively from the atmosphere, the air in our homes. In the tank the CO2 content also gets some help from all the fauna. Guessing its precise CO2 concentration is not easy, given the situation described. Consider that changes of temperature also change the situation, as warmer water will retain less CO2/gases in general.

CO2 injection, being very very short, shifts CO2 by 10x for every 1 point pH drop. So, if you have a 1 point pH drop, the initial CO2 concentration is now 10x higher (e.g. from 2.2 to 22ppm of CO2). That is regardless of kH, but you must have at least ~3 dkH to measure the pH drop, or pH crashes get very real. Thats one way to measure CO2 content, by the pH drop. But the measure itself is the drop, not somehow a translation to CO2 ppms. Example: "I have a 1 point pH drop", "I was able to have a 1.4 point pH drop", or even "I gassed my shrimp to death with 2.0 points pH drop". With a drop from pH 8 to 6, the CO2 concentration is 100x higher (e.g. from 1.2ppm to 120ppm).

Most people have great results with 1 point pH drop. Some, because of several reasons, like the 1.4 to 1.5 region. That is up to you. My interest in this discussion is only clarifying that nailing down the exact CO2 value is not easy, but also not needed. Measuring the mililiters of CO2 being injected per minute is also another way to go, although in this case you have to consider dissolution.
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post #6 of 18 (permalink) Old 04-04-2017, 04:47 PM
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Quote:
Originally Posted by ed.junior View Post
Okay, please let me try and explain a couple things.
The pH/kH table as a way to measure your CO2 content, is at best, very imprecise, going in the direction of unreliabe. That table assumes you have water, some carbonates, co2, and nothing else, almost pure water. The table assumes that pH shifts are limited to CO2. 99% of the time, this is not the case. Changes to the pH by a bit of acidity completely throw the table off. I would have 100+ ppm of CO2, for example, which is just not true.

You could rest your water for some hours, or use an air stone, to find out your water pH when CO2 is in balance with the atmosphere. That DOES give you the pH drop.
The problem is with people saying 1 point pH drop equals 30ppm. That might be the case, might not. George Booth and his studies came up with this value of "minimal" CO2, which varied from 2 to 3ppm in a tank. This is water in a tank, with active fish and bacteria. If we consider this as a starting point, a 1 point pH drop would add 20 to 30ppm.

All gases will, given time, balance themselves between air/water, as explained by Henry's law (partial gas pressure, solubility, etc). So, given time, the roughly 400ppm of CO2 in the atmosphere will cause our water to have around 0.5ppm of CO2. Inside our homes this initial co2 value would go even higher (e.g. 1000ppm), which again would put more CO2 into the water.
Water, resting outside the tank, is getting its CO2 exclusively from the atmosphere, the air in our homes. In the tank the CO2 content also gets some help from all the fauna. Guessing its precise CO2 concentration is not easy, given the situation described. Consider that changes of temperature also change the situation, as warmer water will retain less CO2/gases in general.

CO2 injection, being very very short, shifts CO2 by 10x for every 1 point pH drop. So, if you have a 1 point pH drop, the initial CO2 concentration is now 10x higher (e.g. from 2.2 to 22ppm of CO2). That is regardless of kH, but you must have at least ~3 dkH to measure the pH drop, or pH crashes get very real. Thats one way to measure CO2 content, by the pH drop. But the measure itself is the drop, not somehow a translation to CO2 ppms. Example: "I have a 1 point pH drop", "I was able to have a 1.4 point pH drop", or even "I gassed my shrimp to death with 2.0 points pH drop". With a drop from pH 8 to 6, the CO2 concentration is 100x higher (e.g. from 1.2ppm to 120ppm).

Most people have great results with 1 point pH drop. Some, because of several reasons, like the 1.4 to 1.5 region. That is up to you. My interest in this discussion is only clarifying that nailing down the exact CO2 value is not easy, but also not needed. Measuring the mililiters of CO2 being injected per minute is also another way to go, although in this case you have to consider dissolution.
Good info here. Can I ask a few questions to clear some things up for me as you stated this is not an easy calculation and gets quite complex. From my understanding Co2 is not a linear increase in ppm as PH drops, for the first 1 PH drop equates to roughly 30ppm but the increase of Co2 as you continue to drop your PH continues exponentially so at 1.2PH drop it is almost double the concentration of Co2 at 1 PH drop. Is this correct?

The other question I have is in regards to the PH crash with a low KH. I use ADA Aquasoil which buffers my KH down to about 1KH I have read some of Tom Barrs and threads on this forum that indicate a PH crash with KH lower than 3 is not really anything to be to concerned over here is one thread: https://www.plantedtank.net/forums/8-...out-crash.html

I always like to get opinions on both sides in order to make up my own mind and very much feel like a lot of things in the aquarium world are subject to opinions and results. What works for some may not for others. Thank you in advance

Dan
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post #7 of 18 (permalink) Old 04-04-2017, 06:24 PM
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Quote:
Originally Posted by Dman911 View Post
Good info here. Can I ask a few questions to clear some things up for me as you stated this is not an easy calculation and gets quite complex. From my understanding Co2 is not a linear increase in ppm as PH drops, for the first 1 PH drop equates to roughly 30ppm but the increase of Co2 as you continue to drop your PH continues exponentially so at 1.2PH drop it is almost double the concentration of Co2 at 1 PH drop. Is this correct?

The other question I have is in regards to the PH crash with a low KH. I use ADA Aquasoil which buffers my KH down to about 1KH I have read some of Tom Barrs and threads on this forum that indicate a PH crash with KH lower than 3 is not really anything to be to concerned over.
Hi Dan,

For the CO2 calculation, you are almost 100% correct.

As I said, the co2 concentration in the tank water tends to be around 2-3ppm. This a general value. Your tank could have more, if it did not degassed the co2 during the night, or less, because there is no fish or active bacteria. It depends.

The whole 1 point pH drop adds 30 ppm is the misunderstanding. The "adds" is the issue. Maybe if people used "multiplies" it would be closer to the truth.

Because of the studies of George Booth on CO2 fertilisation/concentration, which found 2-3 ppm of CO2 in tank water, people used this value as the residual co2 content of any tank. As each 1 point pH drop will "multiply" the co2 concentration by 10x, a initial 1 point pH drop will add 30ppm. A second 1 point pH drop would multiply by the 30 by 10x, or add another 270 ppm of co2, making a total of 300 ppm of co2.

The issue is the "adding" portion. The relationship of pH/CO2 is not linear, as you said. I checked it, and from 1.0 point pH drop to 1.3, the value already doubles (e.g. 21ppm to 42ppm).

In regards to the pH crash, the issue is with the CO2 measurement, and not the pH itself. The inability to use a pH probe, or having fast pH swings, not being able to measure pH drop properly, not able to use the pH/kH chart, etc.

I always recommend 3 dKH/dGH, but this number is personal. You can use a lower kH, no issues, it is up to you. For GH, I do recommend at least 3, IME.



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post #8 of 18 (permalink) Old 04-04-2017, 07:17 PM
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Originally Posted by ed.junior View Post
Hi Dan,

For the CO2 calculation, you are almost 100% correct.

As I said, the co2 concentration in the tank water tends to be around 2-3ppm. This a general value. Your tank could have more, if it did not degassed the co2 during the night, or less, because there is no fish or active bacteria. It depends.

The whole 1 point pH drop adds 30 ppm is the misunderstanding. The "adds" is the issue. Maybe if people used "multiplies" it would be closer to the truth.

Because of the studies of George Booth on CO2 fertilisation/concentration, which found 2-3 ppm of CO2 in tank water, people used this value as the residual co2 content of any tank. As each 1 point pH drop will "multiply" the co2 concentration by 10x, a initial 1 point pH drop will add 30ppm. A second 1 point pH drop would multiply by the 30 by 10x, or add another 270 ppm of co2, making a total of 300 ppm of co2.

The issue is the "adding" portion. The relationship of pH/CO2 is not linear, as you said. I checked it, and from 1.0 point pH drop to 1.3, the value already doubles (e.g. 21ppm to 42ppm).

In regards to the pH crash, the issue is with the CO2 measurement, and not the pH itself. The inability to use a pH probe, or having fast pH swings, not being able to measure pH drop properly, not able to use the pH/kH chart, etc.

I always recommend 3 dKH/dGH, but this number is personal. You can use a lower kH, no issues, it is up to you. For GH, I do recommend at least 3, IME.



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Perfect thanks Ed,

So the real issue that comes into play is how much Co2 your water initially contains correct? This clears things up for me so much more.

As for the KH it makes sense to try and keep it 3+ but with aquasoil I think I would do more harm in trying to increase it and having a fluctuation KH than a stable low KH.

Thanks again

Added: any chance you could look at this post? I hate to be a pain but if I don't ask I don't learn and I would be interested in your take on this.

https://www.plantedtank.net/forums/8-...ing-video.html

Dan
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post #9 of 18 (permalink) Old 04-04-2017, 07:20 PM
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Quote:
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Perfect thanks Ed,

So the real issue that comes into play is how much Co2 your water initially contains correct? This clears things up for me so much more.

As for the KH it makes sense to try and keep it 3+ but with aquasoil I think I would do more harm in trying to increase it and having a fluctuation KH than a stable low KH.

Thanks again

Dan
You are right, work with what you have.
Just out of curiosity: what is your tap kH? And how big is your tank?

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post #10 of 18 (permalink) Old 04-04-2017, 07:29 PM
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You are right, work with what you have.
Just out of curiosity: what is your tap kH? And how big is your tank?

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2.8DKH tap. tank is 55Gal water volume after substrate and my underwater waterfall would probably be more like 45ish Gal

Dan
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post #11 of 18 (permalink) Old 04-04-2017, 10:54 PM Thread Starter
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Great info thank you very much. Sooooo... IF my tank has a normal 3ppm co2 and a ph of 6.8 and i inject co2 to make it 6.5, what does that make my co2 level?
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post #12 of 18 (permalink) Old 04-04-2017, 11:30 PM
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Great info thank you very much. Sooooo... IF my tank has a normal 3ppm co2 and a ph of 6.8 and i inject co2 to make it 6.5, what does that make my co2 level?

I'm going to guess 4.7-4.8. If I am at all grasping this concept. Hopefully @ed.junior can confirm or correct me on this.

Changed my answer to 6 lol

Added: appears that at .3 PH drop would be double the initial level... Is this correct Ed?

Dan
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post #13 of 18 (permalink) Old 04-05-2017, 07:26 AM
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Dan is correct. It would double it.

Spider: get 250ml of water and degass it (air it with a pump, shake it in an open container for 5 min, etc) to get your pH when co2 is low. Then check your pH right before CO2 starts (now you know your degass rate, or how much co2 you lose at night), at the middle of your light period (so you what you at that point) and the you do the last measurement right after CO2 is off (and then you get the probably highest concentration, being measured as the lowest drop).

From these measurements you will learn a lot. Trust me. Do not strive for atomic precision, instead go for the overall shape of things: "co2 is there, nice 1.0 drop, ca and mg were added by gh booster, I know my fert routine and concentration being added, etc.. "

It is like you relax because you KNOW what you added, you see the healthy growth, although you cannot exactly tell if it was 28ppm or 34ppm of co2, etc.

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post #14 of 18 (permalink) Old 04-05-2017, 10:00 PM Thread Starter
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I degassed some tank water and it is PH7.6. I shut my co2 off at night and it stays at 6.5 all night. I use a ph meter probe to regulate ph to 6.5 when lights are on then at night no co2 is injected but it stays at 6.5ph all night right up until my co2 goes back on. i have a glass cover over id say 90+ percent of my tank. so at 6.5ph im getting a 1.1 drop?
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post #15 of 18 (permalink) Old 04-06-2017, 07:44 AM
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What is the pH during the day?
It goes from 6.5 at start to what at the end?
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