Another GH KH CC Experiment.

[jarrod0987]

I was curious if using more or less Crushed Coral (Actually using oyster grit in this experiment) would have an effect on the equilibrium over time. The old advice was always to use "one hand full".

I used 2 glasses and put 1 spoon of rinsed Oyster Grit in one and 4 Spoons in the other. I added RODI water. LEt them soak for 1 hour.

I will refer to the 1 spoon glass as glass 1 and the 4 spoon glass as glass 2.
GH and KH are reported in DKH with API kit and pH was read with PHEP 5 from Hanna Instruments.

After 1 hour
Glass 1 pH 7.7 GH 3 KH 2
Glass 2 pH 8.2 GH 5 KH 3

After 26 Hours
Glass 1 pH 7.5 GH 4 KH 3
Glass 2 pH 7.9 GH 6 KH 4.75

After 50 hours (Added top off RODI water)
Glass 1 pH 7.8 GH 5 KH 4
Glass 2 pH 8.0 GH 5 KH 4

After 165 hours
Glass 1 pH 7.7 GH 6 KH 5.5
Glass 2 pH 8.0 GH 7 KH 5.5

Conclusion:
The tests are not super accurate so this is very rough data. It appears that more CC will result in the water buffering faster which is very good. Especially if plants are eating your GH very fast or Bacterial acidification is an issue. However, it appears the stabilization of the parameters is about the same no matter how much is use.

 

[Roz]

Hey, Jarrod

A very interesting experiment!

Did you run a control with tap water minus the shells? Just wondering what the water ph etc was just out of the tap.






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[jarrod0987]

Hey, Jarrod

A very interesting experiment!

Did you run a control with tap water minus the shells? Just wondering what the water ph etc was just out of the tap.






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Wasn't using tap for this. Was using RODI.
Has a theoretical PH of 7.00 but I think I remember reading an average of 7.01. Ph is very unstable when you have no TDS at all. GH 0 KH 0 etc.

 

[Fresh2o]

Yeah, I was thinking about controls as well then realized that you used RODI. Anything other than that (tap/tank) then for sure.
As for use in the aquarium, what are your thoughts on the effects of biological buildup (aka slime) on CC? Does it appreciably reduce its ability to distribute buffering materials to the water column? Would occasionally rinsing and/or replacing the CC overcome this? What got me thinking about this were the chunks of cuttlebone in my shrimp tank. It's in there not so much for buffering but for supplying calcium.


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[jarrod0987]

Yeah, I was thinking about controls as well then realized that you used RODI. Anything other than that (tap/tank) then for sure.
As for use in the aquarium, what are your thoughts on the effects of biological buildup (aka slime) on CC? Does it appreciably reduce its ability to distribute buffering materials to the water column? Would occasionally rinsing and/or replacing the CC overcome this? What got me thinking about this were the chunks of cuttlebone in my shrimp tank. It's in there not so much for buffering but for supplying calcium.


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Hmm. That's a very good point you brought up about the bio film. I never considered it. That may explain why some people report that CC's effect decreases severely over time.

The way D. Walstads book explains it is that the bio film is kind of like a apartment complex for bacteria and is full of channels for them to get water in and out. I know the acid from the bacteria is what actually causes the CC to break apart again.

The tank I have now is only a month old. The Oyster grit is deep inside the soil and intermixed. I don't know if bio film grows there or if acidification prevents it. D. Walstad says in her book this is what she does. She makes no mention of problems over time. I guess we will see as I record PH and GH and KH from time to time. I am told CC goes away over time and so

Thanks for the awesome Question.

 

[Fresh2o]

I forgot about acidification. I was thinking of the biofilm as this inert "blanket" preventing reactions from occurring. Wrong.


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[jarrod0987]

I forgot about acidification. I was thinking of the biofilm as this inert "blanket" preventing reactions from occurring. Wrong.


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I always did too for years until I read her book a few weeks ago. Fascinating read. Very scientific with a dump truck of references and experiments. A person would be hard pressed to dispute the science in this book.

 

[Roz]

Wasn't using tap for this. Was using RODI.

Has a theoretical PH of 7.00 but I think I remember reading an average of 7.01. Ph is very unstable when you have no TDS at all. GH 0 KH 0 etc.

Thanks for the clarification, Jarrod

I have the book you mentioned - will get started on reading it properly, as I want to learn more than I do about water chemistry.

Will keep following this thread with interest


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[jarrod0987]

The Walstad book defiantly covers the chemistry very well. I have been searching for the answers contained in that book for years. I love aquarium chemistry and am crossing over into micro biology a bit. So many just wish to stay in the dark ages of 1970's Aquarium methods. It's nice to see you prefer the light of science. You will be met with much resistance when you try to bring what you learn back here to help people. I suspect you know this already. You have my respect for being brave enough to do it anyways.

 

[jarrod0987]

Update:
I found my old LaMotte Ca test kit today. Works with fresh or salt water. Reagent is old so probably no good but it is dry tablet so those can last a long time. Anyways with API reporting KH of 8 dKH LaMotte reports a Ca Hardness of 100 ppm. It is a tritration test.

 

[jarrod0987]

Update:
Decided to buy a LaMotte test kit to tell how much Ca and Mg the Oyster grit is adding.

Soaked a small handful well rinsed oyster grit in RODI water for 5 days.
Results were 37 ppm Total Hardness. Calcium results were 24 ppm. From this we can extrapolate Mg is 13 ppm. So about a 2 to 1 ratio of Ca to Mg. It is still much more Mg then I expected. If I ever get any more crushed coral I will run the same analysis to see if the ratio is any different.