The Right Substrate

Substrates in the aquarium

Plants use the substrate to grow their roots, but the purpose of growing is to get nutrients or reproduce. Each plant have a different root system, which grow better in different types of substrates. In nature aquatic plants evolved to get use to specific conditions, which are nothing like regular pea gravel. To create more suitable environment for your plants you will have to consider different size and shape of aquarium substrates. Also, how deep will be the layer, and how rich in nutrients and minerals it will be.

Size and Shape

If the size of the substrate is not good for the plant it will cause problems. Too big shape will cause that nutrients will be washed from the roots and plants, won’t grow too well. On the other hand to small substrate will be compact so well that it won’t allow enough oxygen to go thru. It may cause damage to the roots system if the layer is too deep. Good size of aquarium substrate could be size about 0.04-0.12 in (1-3mm) with round shape. Sharp substrate may damage the roots and be not suitable for bottom dwellers like cory’s.

Dirt as a main rooting substrate dirt is used often as a rooting medium, because it holds nutrients very well. It should be compact enough to still let for oxygen exchange and capped with other substrates.

You can mix 0.08-0.12 in (2-3 mm) substrate with others more rich in nutrients.

Nutrient-rich substrate will provide nutrients continuously for a long time. Those kind of nutrients are usually compacted quite well and are kind of soil like regular organic soil or topsoil. It is good to cap it in lower layers so it won’t get water muddy while you pulling plants out or replant. It may be used as a main rooting substrate. Below are some different types of the substrate you may want to know.

Top level substrate  most visible usually used as a thin layer, is more like a decorations medium than rooting medium.

Different substrates

Pea gravel is the most popular form of aquarium gravel. It is round, usually small and has different color. Smaller grades can be used as a main substrate cause it holds nutrients(debris) well between its particles. Aquatic plants won’t get much benefits from the pea gravel unless the debris will accumulate in it.

Quartz gravel often knew as a lime free gravel might be used as a main rooting medium and as well as a to layer, because of its black color. Its grades are usually between 0.04-0.12 in (1-3 mm) so it is good for keeping aquatic plants. It provides better support for plants than pea gravel.

Sand using a sand may cause a problems because its small grade may be to compact, not allowing enough oxygen to get into the roots. The sand is used sometimes as a bottom layer together with the heating cable, This method is already forgotten since there are better ways to keep aquarium plants. It is one of the methods which was popular in the past, because it pushes natural water movements from the substrate and nutrients from the water to the substrate. Needs to be moved gently and regularly from time to time, to prevent anaerobic conditions and toxins build up. With heating cable it is good to use no more than 1.6 in (4 cm) of sand, then water movement will deliver enough oxygen all the way to the bottom of the sand.

Laterite aquarium substrates known as a clay-based substrates, are mainly available as a addiction to the substrate. It has reddish color, because it is reach in iron and releases it for a long time. It is the best to use it as a layer by the bottom third of the substrate or mixed in the middle, where the fain roots absorbs their nutrients.

Nutrient-rich aquaruym substrates – aquasoil those substrate are design specifically for planted tanks. Some of them are based on the laterite or contain mix of the good organic nutrients and minerals, which will be released continuously even thru 3-4 years. Substrates like this is good to use in small quantities, as a thin layer or mixed with the other substrates. However it is not the rule you must follow. You can use a deeper layer of this substrate as long as you will add some lava rocks or ADA Powersand on the bottom. This will help oxygen exchange between deeper layer of the substrate and roots.

Soil-based aquasoil substrate if you are beginner, it is better to avoid soil in the aquarium, because it is very unpredictable. If you will get more experience with aquatic plants, you may try to use soil based substrates as a long term planting medium. Soil contain big amounts of carbon and iron which will benefit aquatic plants, as it will be slowly released to the water and absorbed by the roots. However if you decide to do soil in your aquarium it is a very cheap and effective method. Just remember, cycling the soil takes much more time and you might need to do a lot more water changes.

For the first 3-4 weeks I would recommend doing at least 2x 50% water changes a week. You might wanna use not more than 0.5-inch of soil and cap it with fine gravel or other small grain substrate. Remember to sift it before to remove any kind of remaining roots and cork and use only organic based soil without additives. Also you may need to poke it for the first few weeks, as it will be releasing a gas which might be harmful for fish and invertebrates. It will take a longer to cycle it (up to 3 months), as it will release ammonia and soak minerals and nutrients from the water. After that time you will set for a success for a longer time.

amazon forest soil layers

The climate of the tropical rainforest biome around the world informations about soil layers and temeprature change during the year:

Aerobic and anaerobic substrate conditions

A substrate rich in organic material (waste matter and nutrient-rich substrates) will naturally contain large numbers of bacteria that break down these organics into usable nutrients. The majority of these bacteria quickly use up oxygen, with the result that the substrate becomes anaerobic. In anaerobic conditions, different types of bacteria form, which do not need to use large quantities of oxygen or can create their own oxygen. These anaerobic bacteria can release toxic gases, most notably hydrogen sulphide, which can cause plant roots to rot, damage fish health, and encourage algae to flourish.

However, anaerobic conditions also allow nutrients to become more readily available to plants by preventing the binding of nutrients with oxygen molecules. As the bacteria use up the nitrates, nitrogen is released, which is also an important plants macronutrient.

A mixture of aerobic and anaerobic substrate zones can provide the benefits of both conditions. As long as the substrate is not too fine and compact and/or substrate heating is employed, the combination of a slow-moving current and the release of oxygen by plant roots should prevent the majority of the substrate from becoming anaerobic. Anaerobic patches will then appear in denser areas of substrate without plant roots. Because these patches are small, they will not produce large amounts of toxic gases yet still allow nutrients to be produced and available to the plants. So a low-oxygen substrate is often best, where anaerobic conditions are allowed to develop in some places but not in others.

My tips

I was using innert substrates like eco-complete, caribsea floramax original and black, and I noticed that 4 inches of the substrate is an optimal level (minimum) for the keeping big bunch of plants in your planted tank. Some plants after few months will produce huge roots, which probably would be even bigger if I would have more than 4 inches of substrate. So, it could probably grow bigger. I also noticed that if you will put some pebbles on the top, plants will grow faster because more debris and nutrients will accommodate in the substrate, but it is also harder to clean and cause a risk that the substrate will be too compact and not enough oxygen would get to the roots.

Also not vacuuming a substrate too often helps keep plants fed better. I’ve never been using any root tabs and my plants have never been struggled or showing any deficiencies. Never do deep substrate vacuuming, only the top layer, unless it is on the edge of the aquarium and doesn’t look too aesthetic.

Aquarium substrate – Fluval Stratum

Aquarium Substrate - Fluval Stratum

I used fluval stratum aquasoil and from my experience, while cycling 40 gallons breeder aquarium with co2, it takes up to 3 months to fully establish and get to the point where you don’t need to do that much maintenance. If you won’t add any additives below the substrate. This type of aquasoil will release ammonia around 0.5ppm daily which helps with initial nitrifying bacteria to grow.

You should be able to add first fish around 2 weeks after starting your aquarium with this method. However with more sensitive fish or shrimps I would recommend waiting 2-3 months. It all depends on your tap water quality and is connected with substrate buffering capacity, which tends to soften water Kh and creates less stable conditions for maintaining Ph in the aquarium.

If your water is soft and you supply with co2 it might cause a Ph drop if there will be too much organics (acids) in the water column. This sudden ph drop will cause ph shock to your fish and shrimps. Most likely you will loose them. Happened to me one time in a nano tank, and ended up loosing a few shrimps. So maintaining good water quality in this case is crucial(water changes are the key). It not only removes excess of organics from the water, it also brings back kh. To prevent Ph drop in initial phase you might do a small 10-20% water changes between your regular water changes.

TDS (Total Dissolved Salts)

TDS MeterYou can get TDS meter which will shortly measure all kind of elements in the water. Measure the TDS of your tap water. Notice that cold, warm and hot water will have a completely different TDS. Higher TDS from warmer tap water will come from the copper pipes in the heater. That is why the best is to use cold water and prepare it earlier with the heater so it has the same water temperature like your aquarium water.

Now once you know TDS of water you use for water changes you can add it. Note that every number over your tap in TDS reading in the aquarium will mean something different. It might tell you nitrates, organics, salts, fertilizer, minerals, additives. All that will bring your TDS up. You can estimate what is included in your TDS by measuring it before and after adding anything to your aquarium. This way you can calculate the difference and you will know how much of the TDS value are the stuff you add. The rest will be how the stuff that in bigger amount will cause problems like organics ammonia nitrates etc.

For the planted tank with tap water parameters: gh5 kh5 and initial TDS of tap water 150 TDS it is okay to keep your aquarium TDS from 200-300 TDS.

If you use RO water you might wanna aim for TDS 130-150

Aquarium substrate – ADA Amazonia

Aquarium substrate ADA Amazonia

Another very good aquarium substrate – aquasoil is ADA Amazonia. It has even more nutrients, but leeches much more ammonia on the beginning. It needs much more water changes for the first 2-3 weeks. Depending on how much you added and how much water volume do you have. You can lower amount of water changes by using dry bacteria powder. Some substrate from established aquarium underneath and established filter or media from another aquarium. This will help you spread the ammonia quicker so it won’t build up that fast. (Correct me if I’m wrong) Those are just tips from my own experience.

Aquarium Substrate – Tropica Aquasoil

Aquarium Substrate - Tropica Aquasoil

Another good aquasoil is made by a Tropica brand. I did not try it but from what I was told is very reliable and consistent in its composition. This means each bag will have relatively the same amount of nutrients.



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