Browning and melting HC

[Silviu Man]

I am sorry but my assertion about CO2 used during night is correct. Very short and simple speaking about this ...

There are two kind of reactions that generate, in the end, organic matter : photochemical and non-photochemical. During light time, photochemical reactions use CO2 for photosynthesis genereting O2 and stocking energy as chemical energy in the form of ATP (adenosine triphosphate) that is a < nucleoside triphosphate >. During dark time, there are non-photochemical reactions < Calvin cycle > when ATP is used, together with CO2 for genereting glucosis. The quantity of CO2 used in these reactions is different indeed but CO2 is used continously, in different ratio. If in the tank there is a large stock of animals, CO2 produced by them could be enough for non-photochemical reactions but is important to know also what kind of plants you have in the tank from the requirements point of view. On the oposit to this reactions is Krebs cycle that take place in the animal organisms when energetic substances are used to generate energy in form of ATP and generationg CO2. Basicaly, this because why plants need CO2 during night too.

So, that CO2 addition program should work as a minimal solution. I am keeping CO2 addition continuous because is cheap and efficient (I have a cylinder that should be filled once in 2-3 months so is no reason not to do it). If you have a problem in filling it with gas, than I would apply that program.

 

[ceg4048]

During dark time, there are non-photochemical reactions < Calvin cycle > when ATP is used, together with CO2 for genereting glucosis. The quantity of CO2 used in these reactions is different indeed but CO2 is used continously, in different ratio.

Hi,
Sorry, you have confused the so-called "Dark Reaction" with your definition of "Dark Time". Additionally, you are possibly confusing the ATP mechanisms of plants with the mechanism of bacteria and mitochondria.

There are two "Photosystems" which, when combined, result in sugar production in plants:

Photosystem II, which converts light energy to chemical energy (ATP and NADPH). This energy, bound within ATP is then passed on to the next system
Photosystem I, which contains the Calvin Cycle mechanism and uses the ATP generated in PS II to produce the carbohydrates. The CO2 collected by Rubisco is sent to, and is processed in this area.

Since the activity of PS I is totally dependent on the ATP and NADPH output of PS II, no Calvin Cycle functions can occur if the ATP energy is not being produced in PS II.
There is absolutely no photosynthetic activity or carbohydrate manufacturing activity during lights off. This activity is strictly regulated by specific enzymes produced by the light dependent PS II:
A) Ferrodoxin regulation. Ferrodoxin is an Iron-Sulfur protein which acts as an electric capacitor and which moves electrons around in the ATP production cycle.
Deactivation of Ferrodoxin ensures halting of the production of ATP.
B) Rubisco Activase, which, as the name implies regulates the it's ability to collect and transport CO2.
Deactivation of Rubisco Activase ensures that Rubisco cannot attract, hold or transport CO2 and thuse ensures disabling of the Calvin Cycle.


So when PS II is shut down by darkness this signals a change in the behavior/availability of Ferrodoxin and Rubisco.
When the light shuts down, therefore, both Photosystems I and II shut down and are LOCKED DOWN.

By the way, remember we always talk about ensuring that the light is low and the CO2 concentration (lowest pH) at it's highest at lights on?
Well, sports fans, Items A) and B) are specifically the reasons. Photosynthesis mechanisms are DISABLED at night. So when you turn the lights on, the plants actually are at a disadvantage because these mechanisms do not work immediately and the light damages their tissue structure until the engine gets warmed up. It takes about 1/2 hour or so for the systems to be ENABLED and functioning.

Algae do not have such complex mechanisms so when the light comes on they can come up to peak efficiency almost immediately.

Again, that's why most of the CO2 problems we have in our tanks actually are initiated when the lights first come on.


There is no point injecting CO2 at night, especially if you are concerned about the health of the fish.
Having said that, some folks do run their CO2 24 hours per day to reduce the complications of using timers and so forth, but none of these reasons have anything to do with carbohydrate production at night.

It is true hat some aquatic plants have mechanisms to collect and store CO2 in various forms, such as Malic Acid.
The CO2 is later extracted from the acid and used when the light comes on. But this is something completely different and is more relevant to low CO2 scenarios.


Cheers,

 

[gabriel.basso]

Just to post an update

Now I can say that HC was melting due to transitioning to immersed form and I guess also dur to ammonia peaks from the new setup (mainly from substrate). Now, after 2 months it is thriving and spreading really well.

So, for the future readers of this post: check water flow distribution and be patient.

Cheers

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