Redox Reactions: Oxidation and Reduction

I read a recent article that is easily found in search that is admittedly well written dealing with Aquarium Redox, with a good explanation as to what Redox is and more, however this article still chooses to repeat much of the same tired old information about only the positives of the oxidative side of the Redox equation, missing the evidence that the reduction side is also VERY important to a healthy Aquarium Redox Balance (I noted that the sources this particular article sited were all more than 15 years old which may explain much of the out of date information).

Oxidation and Reduction Reactions (Redox Reactions)

Oxidation and Reduction Reactions

Photosynthesis is a redox reaction. this means that h2o …

Important; what is often missed, is that although you may test and, for instance find, high calcium levels in an aquarium via a GH over 300, this does not necessarily mean you have any Redox reduction as I should point out that very basic fact of Redox reduction is the donor (such as calcium) transfers electrons to another substance, and is thus, oxidized itself.
, meaning your GH test (or Calcium, Magnesium, etc tests in saltwater) may tell you that you have ample or even too much calcium, HOWEVER these calcium molecules may have already given up their electrons to other molecules such as fish cell molecules so as to achieve a state of balance in aquarium Redox.

REDOX REACTION: Photosynthesis - YouTube

This again is where many will claim that their calcium or other minerals are high enough or even too high (as many still get INCORRECTLY stressed about the high GH brought on by Wonder Shells, totally missing that these mineral blocks are constantly reducing the water via their donation of electrons!).
This is also where water changes and UV Sterilization also help as these processes constantly balance out Redox.
Since water changes (which also aid in oxidation, which is the other side of the equation) can only be done in intervals.
Unless you have a flow through system, the use of mineral blocks, or other water conditioners as well as UV Sterilization to keep a more steady flow of electrolyte donation is important.

Photosynthesis requires light. But what is light? To answer this question, we will answer three other questions in the next few pages:

explain the role of REDOX reactions in photosynthesis?

Redox, also known as Redox Potential, oxidation potential, & ORP (oxidation reduction potential) describes the ability for the loss of an electron by a molecule, atom or ion to the gain of an electron by another molecule, atom or ion.
Without this ability to gain electrons, many minerals cannot be absorbed and properly assimilated, especially in times of stress.

To determine how the chemical DCMU (3(3,4-dichlorophenyl)-1,1-demethylurea) affects the light reactions of photosynthesis.

What Happens in the Light Reaction of Photosynthesis

A more basic aspect of Redox Balance is the water we use can have a direct impact as well.
The water we use, whether from the tap or Reverse Osmosis/De-ionized this too can affect your Redox Balance, sometimes negatively. Generally speaking tap water if only altered with chlorine or chloramines may or may not have the necessary mineral cations to bring a poor Redox back into balance.
The use of RO or DI water, while a very practical way to improve and control water parameters (especially with soft water freshwater species or reef aquaria), one should note that the necessary mineral positive mineral ions (cations) are usually gone (removed). The resulting excess oxygen and more acid water is often way too high of an oxidizing environment.
For this reason it is often important to re-minerals these water sources with products such as SeaChem Replenish or Wonder Shells.

You should already know the overall chemical reaction of photosynthesis:

What Kind of Reaction Is Photosynthesis? | Sciencing

In eukaryotes the light reactions of photosynthesis occur in the thylakoids of chloroplasts. Chloroplasts appear as stacked structures. These stacks are called grana, which consist of thylakoids that are actually flattened membranes. Thylakoids house the essential components of the light reactions of photosynthesis. The thylakoid is covered with several types of pigments arranged in photosystems. (This figure depicts chlorophyll molecules embedded in a photosystem.) There are two types of photosystems, and each consists of a few hundred pigment molecules.

We know that redox reactions occur in the direction of stronger to weaker oxidizing agent (just ..

How to Balance Redox Reactions (with Pictures) - wikiHow

So it is very important to keep a healthy Redox Balance via both sides of the Redox equation;
(a) Normal oxidizers such as proper/optimum dissolved oxygen levels
(b) To counter oxidative stress (often artificially induced in our aquariums); via proper positively charged mineral levels (such as Calcium and Magnesium) and even level 1 or higher UV Sterilization.