What Aquarium Substrate is Right For Your Fish Tank?

The substrate you use for your freshwater aquarium plays an important role in the overall biological cycle. Beneficial bacteria will eventually grow on the substrate helping to break down the waste in the fish tank. Substrate is also very useful for anchoring live plants and other decorations in the aquarium.

Is it necessary to have substrate?

It’s not totally necessary to have aquarium substrate and you may prefer the look without it. In fact, your fish tank is much easier to clean because all you are doing is vacuuming the waste off the bottom not sifting through substrate. However, without substrate the tank can’t build as much bacteria to break down the waste and excess food from your fish. Substrate also hides the waste somewhat, so if you have no substrate your tank will look like hell in no time. If you want live plants, substrate is a must.

Is gravel or sand better for an aquarium?

It’s really a function of what type of fish you want to keep, what kind of look you want, type of filter you want, and how often you want to clean it.

The advantages of using gravel are that it can look nice, comes in different colors and sizes, and hides the fish waste better, so you won’t have to clean it as often. If you want to use and under gravel filter, then you would need to use gravel as a substrate.

Some species of fish might not be ideal for a gravel tank, such as, loaches or corys that use their feelers for food scrounging. The feelers may become damaged over time with sharper-edged gravel.

Gravel also tend to keep the pH high because the gravel has a buffering effect.

If you go the gravel route with bottom feeders, get smaller pea-sized gravel with smooth edges. The larger gravel are for larger fish.

Sand looks a little more natural in your fish tank. Certain types of fish like loaches like to burrow in the sand turning over the sand and waste so it looks cleaner. Sand also stabilizes the pH better than gravel.

One main disadvantage to sand is that waste shows a lot faster and therefore it takes more maintenance to keep it looking clean. Vacuuming a sand tank is also tricker and takes longer than gravel. If you have the right type of fish that like to burrow, then they will do most of the work for you. You don’t want fish that produce a lot of waste for a sand bottom.

One thing you need to be aware of with sand substrate are gas pockets. They can be deadly to your fish. What happens are pockets of air will form in the sand. If waste gathers in those pockets and decomposes there, nitrite and ammonia gas will build up. When that gas eventually releases, it could cause harm to your fish. To prevent that, you need to regularly and diligently vacuum the tank, and perform frequent water changes. Rake your sand after each water change.

What is the best aquarium substrate for plants?

You could literally write a book on the subject, but just understand that certain plants get their nutrients from the water and certain plants get their nutrients from soil. Most plants for an aquarium feed off of the water nutrients.

Some aquarists like to put down a layer of organic soil before the substrate on root soil feeding plants. A more efficient way is to get some nutrient dense volcanic soil substrate designed for plants like the Fluval Plant and Shrimp Stratum.

Keep in mind that the nutrients will eventually run out, and you will have to fortify the soil somehow.

Sand is not the best for live plants, because the plants cannot root properly in the condensed, wet fine sand.

Types of Aquarium Substrate:

Pea gravel

– Comes in many different grades and colors that can be combined for an interesting look. It has a good open structure to allow oxygenated water flow to all parts of the substrate bed. The mineral content keeps the pH level neutral or alkaline.

Quartz gravel

– An inert material used a great deal in aquariums. It provides a perfect substrate for healthy root growth.

Silver Sand

– Very fine inert grains that don’t make the water cloudy.

Lime-free gravel

– Makes a fabulous inert substrate that is first-rate for plant health.

Alfagrog –

Is a porous, inert ceramic with a large surface area. The large surface area promotes good bacteria growth for tank waste.

What additives should I use with substrate?

Most substrates do not contain nutrients to support plant life, therefore the nutrients must be added. There are some brands that have all the nutrients already included. Most online pet stores carry them.

Laterite is the most commonly used nutrient for substrate without nutrients already included. It’s a clay-based powder containing iron, which is important for sustaining plants. Just spread some over the substrate and mix it in before adding water.

How deep should the substrate be in a planted aquarium?

Gravel substrate should be about 3 inches deep. It will vary because you should slope the substrate from back to front. So maybe half-inch deeper in the back and half-inch shallower in the front.

How do you clean sand in a fish tank?

The best way to clean sand in a fish tank is to stir up waste with your fingers so everything settles on top. Then you would vacuum the waste off the top. You have to hold the vacuum slightly above the sand, so you don’t start sucking sand up in the vacuum.

How much sand should you put in your aquarium?

Sand substrates should be kept shallower, due to the possibilities of detritus building up in the sand and ease of cleaning. One and a half to two inches of fine sand should be good unless you have a tank with high circulation.

What substrate goes with which fish?

For bottom feeder fish like cory catfish and loach, a fine sand substrate works best. A very small, smooth pea-sized gravel would work too. These types of fish like to turn over the substrate when foraging for food, so they need to be able to do that. The corys have little feelers that get damaged if the substrate is sharp. Geophagus is also good at keeping sand substrate clean.

How do you slope substrate?

Substrate should be higher in the back then in the front. It displays nicer and waste will roll down to the front, making cleaning easier.

Jake Willhoite
Jake runs AnimalDome.com and has had cats and dogs his entire life. As a kid his family adopted several dogs from the local shelter which set him down the path of animal rescue.
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