Active Substrates - How do they work ?

[daveron]

I know that they are meant to lower pH, and keep it stable, but what is actually in them that regulates the water parameters ? Are there different substances that get your pH down, and different that buffer them at a certain level.

Are all active substrates designed for shrimp tanks pretty much the same, or are they actually significantly different from each other ?

I would be grateful for explaining, or sharing some articles which provide  insight about this.

[Zoidburg]

My knowledge is limited, but what I do know is that they help to buffer the water by removing KH, thus lowering the pH. Using tap water with KH or remineralized RO water with KH added in causes the substrate to lose it's buffering capacity quicker.

 

Different substrates may be able to buffer the water to different pH's, although it may also depend on how much GH is in the water. Most should be able to buffer between 5.8 to 6.8 pH.

Tannins from leaf litter and driftwood as well as peat moss may help to lower the pH level as well.

[jayc]

This is probably a difficult question to answer since the substrate manufacturing ingredients and process is a trade secret that I'm sure ADA or any of the other companies would not want to disclose. So clearly I'm not going to be in the know about how it works exactly, but I think this is a very close approximation.

But from a simplistic view, I understand that these planted substrates are actually soil. The soil is shaped into these roundish pellets and fired in some kiln to form the hard granules that we know of.

But prior to turning it into granules, they probably add a mix of nutrients, like calcium, magnesium, potassium, etc. Some companies might add clay, sand or other mixes of soil to bulk up the mass, and therefore changes it's colour and texture. 

 

Being made up of predominantly soil, the substrate contains natural organic acids and tannins. It is this humic acid that counters the carbonates, which we measure as KH, and lowers the KH. Acids break down the bonds that form a carbonate ion  CO₃−₂ . 

Carbonates exists in the water as bicarbonate ions (HCO3-), and the bicarbonate ions further break down into H+ and CO3-2 ions. More H+ ions makes the water more acidic.

It doesn't magically remove KH and throws it out of your tank. It just changes it's molecular form into something else. There are no magical disappearing acts in nature.

Note: the natural process of nitrification by bacteria also lowers acidity of the water by consuming the waste leaving H ions as a byproduct.

 

Being pelleted into a hard granule means that the nutrients and organic acids and whatnot is locked in and released in a controlled manner. 

It also increases durability, so that it doesn't break apart and revert to mud.

Dump a whole lot of soil from your garden compost into a tank and you'll see a release of nutrients in one big bang into the water column - not where the plants need it at the roots. Resulting in an unsightly tank, but also feeding algae in the longer term. Loose soil will be pushed all around by the water currents as well, not what you want.

So the manufacturers have come up with these soil granules that lock in all the goodness, and releases it in a more controlled manner. Obviously, some companies do it differently and their products vary from colour to nutrient levels to durability.

Edited December 12, 2016 by jayc