Osmosis in Planted Aquariums
Osmosis is the process in which any solvent moves through a membrane in a direction from lower concentration to higher concentration that tends to equalize the solutes’ concentration on both sides. The membrane should be semi-permeable and good examples are the cells of the aquatic faunas and plants.
So why we should know about Osmosis and how it relates to our planted aquariums and successfully keeping it? In this article, we will discuss all about Osmosis in Planted Aquariums.
Table of Contents
Osmosis in Planted Aquariums?
What are the Effects in Floras and Faunas?
How Does Osmosis Relate to the Quality of Water We are Using?
TDS is not a Worthless Measurement
Osmosis in Planted Aquariums?
So let me repeat again: Osmosis is the process in which any solvent (water) moves through a semi-permeable membrane (fish or plant cells) in a direction from lower concentration to higher concentration that tends to equalize the solutes’ (salts, ions, sugars, dissolved solids, etc.) concentration on both sides.
This is due to osmotic pressure and is used by every living thing to regulate its cell solute concentrations within safe levels (osmoregulation). Osmotic pressure is spontaneous and cells doesn’t need to expend energy.
Without osmoregulation, it changes the fish’s blood pH, digestive tract, and immune system, greatly affecting its health and risk of catching diseases or worse death.
Without osmoregulation, plants’ water and nutrients uptake, photosynthesis, and general stability will be affected (resulting in melting or wilting). Within the plant, Osmosis ensures that all cells and structures have the correct water pressure and volume. This is also the reason that plants remain upright.
For example, if you put a freshwater fish in pure water free of any minerals and other salts like distilled water, this means that the fish cells have more solutes than the water outside it. This is called a Hypotonic Solution.
When this occurs, more water will enter the cell than leave it to balance out the concentration of solutes on both sides.
The water forces its way into the fish due to osmotic pressure (lower concentrations to higher concentrations) and quickly dissolves the solutes in the fish’s body. The fish cell will continually swell, and under such conditions, the fish cell may burst = dead fish.
Dutch Style Planted Aquarium Aquascaped by Omar Krishnan Afuang Philippines
So what if the freshwater fish is put in water with very high solutes than the water in its cells (in the case of salt water or water with very high dissolved solutes – TDS/Hardness/Salts)? The fish will continually lose its water within its body (water goes from lower concentrations to high concentrations).
This is called a Hypertonic Solution, the opposite of the Hypotonic solution above. In this case, more water leaves the cell than enters it.
As a result of this, the osmotic pressure is too much, and the fish could not adapt faster than it is losing water until its cells shriveled = another dead fish.
Another example: this is why slugs and snails shrivel and die when you sprinkle salt on them. The water in their cells wants to equalize with the high concentration of salt outside the cells.
Floras and Faunas in our aquariums are affected by Osmosis differently. The floras and faunas can tolerate different solutions.
For example, in the Hypotonic solution mentioned above, fish cells will burst because of too much water entering. However, in a plant, plant cells need more water than animal cells.
The plant cells have more solute than the water outside so water rushes in. The plant cell could burst, but thanks to a rigid wall surrounding the cells, it will not. The cells expand until it pushes against their cell wall, creating pressure.
No more water can enter and this is the main line of support why terrestrial and aquatic plants remain upright for non-woody stems. A hypotonic solution is ideal for plant cells.
How about the Hypertonic solution for plants’ and animals’ cells? Water will rush out of both plant and fish cells and the cells will shrivel: for fish = dead; for plant = since there is no pressure anymore and less water = wilt.
So what if we have equal amount of solutes in the cell and the water outside? This is called an Isotonic solution.
An Isotonic solution is ideal for animals including our aquatic faunas. But the ideal balance is impossible to achieve in our planted aquariums. Not to mention how to determine the ideal balance.
How do you determine the amount of solutes in plants and fish cells and compare it to your aquarium water? Yeah, good luck with that.
How about an isotonic solution in plants? The plant cells are no longer full of water or not turgid anymore, with not enough pressure to make them stiff and upright. The plant’s leaves will droop as well.
So what are we implying here? How does Osmosis relate to the quality of water we used in our planted aquariums?
As it turns out, plants cannot thrive in spotless water due to the absence of the nutrients needed to create their own food.
Aquatic faunas and floras don’t only need pure H2O molecules. They also need salts (KH, carbonates), nutrients (Ammonium, NPK, dissolved CO2 for plants), and minerals (calcium, magnesium, iron, etc.) present in the water but also not too much.
Crystal Red Shrimps
Using a zero KH-GH-TDS water source in a bare aquarium or container is like the hypotonic scenario above for our faunas. Actually, zero final TDS water in a planted aquarium is pretty much impossible.
Anything that you add to your planted aquarium from the substrate, hardscape, fertilizers, plants, water conditioners, fish food, dead organic matter, dissolved solids, CO2 injection, etc. will add to your TDS.
So we are safe on this low extreme end. We will recommend at the very least maintaining 80 TDS after your planted aquarium has been established.
You can still go lower up to 20 ppm TDS if not impossible in a planted aquarium, but there is no point lowering to that as it takes a lot of effort, OCD to kick in, and headaches. You will not be able to enjoy your planted aquarium that way.
On the other extreme end, using a very high KH-GH-TDS water source is like the Hypertonic scenario, very high and with unknown solutes compared to what our plants and fish are used to. As an example, using super hard deep-well water (GH in excess of 530 ppm).
Or a very high baseline TDS water source in excess of 500, etc. Take note, that 500 TDS is just the baseline TDS of the water source. It will still increase once you use it with your planted aquarium.
Overstocking, overfeeding, tank neglect, and a filter that cannot keep up with the load can also lead to water with very high dissolved solids (TDS).
Planted Aquarium Aquascaped by Brylle Isaac Philippines
So to summarize, in an established planted aquarium, we will recommend maintaining your water from 80 TDS on the lower end up to 300 TDS on the higher end to save you from all the headaches and anxieties. This is after you set up and added everything to your planted aquarium.
Personally, I keep my planted aquarium from 120 to 130 ppm TDS after and before water change respectively. Very narrow, but it is manageable because I am using RO/DI water with remineralization. The baseline TDS of my RO/DI nowadays is 26 to 27 ppm. I know what I put in my tank.
Nature Aquarium Aquascaped by Bart Capundag Philippines
It is the number that I settled with that works for my plants and fish. Every planted tank is unique and everyone should come up with a number that works for their setup. So we recommended a safe, manageable, and feasible range above.
You may also realize that TDS is not really a worthless measurement to take with regard to planted aquariums. It is one of the most important water parameters. It will affect the osmoregulation in your faunas and floras cells.
It can affect their health, immune system, ability to purge waste from their body, nutrient and water intake, stability, etc.
Many issues with faunas that get attributed to large pH swings (you mess with your KH), or water hardness are actually caused by Osmotic shock.
This is also true if you don’t drip acclimate your newly bought fish and didn’t research their preferred water parameters. It can cause the melting or wilting of aquatic plants too.
In this article, we discussed what Osmosis is and its relation to the quality of water we are using in our planted aquariums.
It can affect our faunas and floras’ well-being and we also recommended a safe and manageable range of TDS that we can maintain.
Want to Explore More?
It is mostly considered to be one of the most popular aquascape designs today. And for an excellent reason, this style is simply breathtaking and very natural looking. We are replicating nature, after all.
Nature-style aquascape uses natural wood branches or driftwood, rocks, and stones to project a natural theme and provide a sense of flow to the form and composition.
The fastest method to cycle your tank is to use your old filter media, gravel, soil, hardscapes, and even part of the old water from your old aquarium to your newly planted aquarium.
But this needs careful planning and execution for it to be successful.
After choosing the ideal location of your aquarium at your home and the stand to be used, you have to determine your planted aquarium tank dimensions. You have to take measurements of the Length, Width, and Height (LxWxH) of the stand. Take into consideration where you will put your equipment, tools such as aquarium filter, aquascaping tools (straight tweezers, curved scissors), siphon, etc.
Our aquarium is very much like a septic tank for our faunas (fish/es, snails, and shrimps). Whenever they excrete, or you are overfeeding, and those organics started to decay, or when dead plant matter decays, Ammonia is produced. When faunas die and decay, they will also produce Ammonia, lots of it actually, until they are removed. This causes ammonia levels in our tank to spike.
They are also called hang-on-back filters (HOB), and are designed to hang on the back of your aquarium, eing! Power filters are the most commonly used planted aquarium filter because they provide good to excellent mechanical and biological filtration simultaneously. They can also provide the needed water surface agitation for aerating your water.