What Is Fluval Stratum (And Is It Any Good)?

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Fluval Stratum is a volcanic soil that comes in a compressed ball form and has a very porous structure. Fluval Stratum is collected from the foothills of Mount Aso Volcano in Japan. Volcanic soil substrates such as Fluval Stratum contain a large number of beneficial compounds which have a positive effect on plant growth. These compounds include potassium and iron. Stratum also contains phosphorus which helps create and maintain water conditions enjoyed by aquatic plants.

Fluval Stratum has been specially developed for both planted aquariums and shrimp tanks. The light, porous nature of the Stratum allows plant roots to penetrate the substrate easily and get a good foothold. The porous design of the Stratum also provides the perfect home for beneficial, nitrifying bacteria, which will colonize the Fluval Stratum, aiding your filter in processing the biological waste from your fish. The Stratum will also help maintain the pH in your aquarium.

Fluval Stratum is also often recommended for shrimp tanks. Because of the way the substrate lays on the bottom of the aquarium, it provides countless hiding places and spaces for newborn shrimp. For newborn shrimp, out of sight is out of mind, reducing the chances that someone else in the aquarium will eat them.

Fluval Plant and Shrimp Stratum, For Fish Tanks, 8.8 lbs.,
4,021 Reviews
Fluval Plant and Shrimp Stratum, For Fish Tanks, 8.8 lbs.,
  • Fluval Stratum is made of mineral rich volcanic soil
  • Stimulates strong aquarium plant growth
  • Promotes neutral to mildly acidic pH
  • Suitable for live plants or shrimp
  • 8.8 lb. bag

Last update on 2023-05-21 / Affiliate links / Images from Amazon Product Advertising API

Fluval Stratum Pros and Cons

Below is a list of some of the pros and cons I have found using Fluval Stratum over the last few years.

Pros of Fluval Stratum

  • It is easy for plant roots to penetrate and spread through
  • Its dark color gives a very natural feel to the aquarium
  • Its porous structure is designed to be beneficial for beneficial nitrifying bacteria
  • It doesn’t discolor the water
  • The gaps between individual pieces of Stratum make perfect refuges for baby shrimp

Cons of Fluval Stratum

  • It is relatively expensive compared to normal aquarium gravel
  • After a few years, it may breakdown and need replacing
  • It can be hard to secure large plants before the roots fully form
  • It can’t be gravel vacuumed

Taking all of the above into account, and having used Stratum in a number of tanks, including the one above, I certainly believe the pros outweigh the cons.

What are the Main Features of Fluval Stratum?

Fluval Stratum is essentially small, dark, round balls of volcanic soil which has been developed especially for planted aquariums.

Because the individual balls so Stratum are so light, plant roots find it easy to penetrate through and get a grip. Plants can also easily extract nutrients from deep in the substrate.

Is Fluval Stratum A Good Substrate?

I use Fluval Stratum in a 155 gallon planted aquarium. The tank is the one shown in the image above. I planted it up originally in January 2020 with around 30 small Crypt Wendtii plants. I have been amazed at how easily the Crypts spread (they grow by sending runners out under the substrate).

If I am honest, I haven’t added any fertilizer, either in liquid form or root tabs, which is not something I would recommend, it just kind of happened that way.

I would definitely describe Fluval Stratum as a good substrate. I have been really pleased with the Stratum and I would certainly recommend it to others.

Do You Need To Rinse Fluval Stratum?

When you first get your Fluval Stratum you will need to rinse it. It should be washed in cold running water. Be aware, Fluval Stratum is a delicate substance. If you blast it with fast running water, it will break up.

When I first got my Fluval Stratum I opened the bag and poured about a third of the bag into a large strainer. I washed it gently in slow-flowing cold water for a couple of minutes. Do not be tempted to get your hand in there to move the stratum around like you might do when washing gravel or sand. If you do, it will all break up very quickly.

Even after washing your Stratum, you will notice it still turns the water slightly cloudy when you fill your aquarium up for the first time. DO NOT PANIC! You will find that within 24 to 48 hours of your filter running the water becomes crystal clear.

Here is a video from Fluval Aquatics themselves describing some of the benefits of using Stratum.

How Much Fluval Stratum Do I Need?

Fluval Stratum is expensive and you will want to make sure you don’t buy too much, or leave yourself short making the tank look too sparse.

In a recent experiment, I discovered that you need around 5.5lbs (2.4kg) per 1” (2.5cm) depth of substrate for every 1 square foot of aquarium footprint. This means that my 155-gallon aquarium, which has a footprint of 10 SqFt, required 55lbs (24kg) of Stratum for a 1” (2.5cm) layer.

The table below helps you work out how much Fluval Stratum you would need for your aquarium. Just look down the left-hand column to find your size aquarium, then look across and see how much Stratum you would need for a 1” layer, a 2” layer, or a 3” layer.

Aquarium VolumeAquarium Size (L x W x H inches)1″ Layer2″ Layer3″ Layer
20 Gallon High24 x 12 x 1611lbs (5.0kg)22lbs (10.0kg)33lbs (15.0kg)
20 Gallon Long30 x 12 x 1213.5lbs (6.1kg)27.0lbs (12.2kg)40.5lbs (18.3kg)
25 Gallon24 x 12 x 2011lbs (5.0kg)22lbs (10.0kg)33lbs (15.0kg)
29 Gallon30 x 12 x 1813.5lbs (6.1kg)27.0lbs (12.2kg)40.5lbs (18.3kg)
30 Gallon Breeder36 x 18 x 1224.5lbs (11.1kg)49.0lbs (22.2kg)73.5lbs (33.3kg)
40 Gallon Long48 x 12 x 1622lbs (10.0kg)44lbs (20.0kg)66lbs (40.0kg)
40 Gallon Breeder36 x 18 x 1624.5lbs (11.1kg)49.0lbs (22.2kg)73.5lbs (33.3kg)
50 Gallon36 x 18 x 1924.5lbs (11.1kg)49.0lbs (22.2kg)73.5lbs (33.3kg)
55 Gallon48 x 13 x 2127.5lbs (12.5kg)55.0lbs (25.0kg)73.5lbs (37.5kg)
65 Gallon36 x 18 x 2424.5lbs (11.1kg)49.0lbs (22.2kg)73.5lbs (33.3kg)
75 Gallon48 x 18 x 2133lbs (15.0kg)66lbs (30.0kg)99lbs (45.0kg)
90 Gallon48 x 18 x 2433lbs (15.0kg)66lbs (30.0kg)99lbs (45.0kg)
125 Gallon72 x 18 x 2149.5lbs (22.5kg)99lbs (45.0kg)148.5lbs (67.5kg)
150 Gallon72 x 18 x 2849.5lbs (22.5kg)99lbs (45.0kg)148.5lbs (67.5kg)
180 Gallon72 x 24 x 2566lbs (30.0kg)132lbs (60.0kg)198lbs (90.0kg)

When I scaped my 155-gallon aquarium, I started by placing a layer of lighting diffuser (sometimes called egg crate) on the bottom of the aquarium. I then placed all my rocks and wood on top of the lighting diffuser.

I could then fill in around the rocks with the stratum. This helped me in a number of ways. Firstly, having the rocks on the lighting diffuser meant they could never touch the glass directly, preventing them from cracking the base of the tank.

Secondly, I could use less Stratum as there was no point in having the substrate under the rocks. It is just a waste of money.

The third benefit to getting all the hardscape in before the Fluval Stratum is, because the stratum is quite delicate, adding and moving rocks around will just break it up. If you get all the rocks in, make sure you are happy with the hardscape, then add the Stratum, it doesn’t get broken up at all.

Fluval Plant and Shrimp Stratum, For Fish Tanks, 8.8 lbs.,
4,021 Reviews
Fluval Plant and Shrimp Stratum, For Fish Tanks, 8.8 lbs.,
  • Fluval Stratum is made of mineral rich volcanic soil
  • Stimulates strong aquarium plant growth
  • Promotes neutral to mildly acidic pH
  • Suitable for live plants or shrimp
  • 8.8 lb. bag

Last update on 2023-05-21 / Affiliate links / Images from Amazon Product Advertising API

Does Fluval Stratum Lower PH?

According to Fluvals’ own literature, Stratum ‘Helps support neutral to slightly acidic pH’. I contacted Fluval to ask if Stratum actually lowers pH. They replied to say;

’Fluval Stratum will not increase the PH only balance it out to correct levels.’ – email from Fluval Customer Services 16th March 2021

They then followed this with sales information from the side of the packet. To date, I can’t find any evidence that Fluval Stratum will actively lower

Does Fluval Stratum Leach Ammonia?

No, Fluval Stratum doesn’t leach ammonia. I have never seen an ammonia spike when using Stratum.

Does Fluval Stratum Contain Nutrients?

Because Fluval Stratum is made from volcanic soil, it contains compounds that have a positive effect on plant growth. These compounds include potassium, iron, and phosphorus.

These compounds alone do not provide sufficient nutrients for most aquatic plants, so additional nutrients will need to be supplied for most plants either in liquid or root tab form.

Does Fluval Stratum Breakdown?

According to Fluval, Stratum will last about 1.5 to 2 years. At the time of writing, my Stratum has been in the aquarium for almost 1.5 years and I see no signs of it breaking down or needing replacing.

There are some circumstances where Fluval Stratum will break down prematurely. If you gravel vac your Stratum, the tumbling action will cause it to break up. Equally, fish that like to dig, such as goldfish should be avoided. The constant digging by the goldfish, taking the stratum into their mouth, then spitting it back out will also cause the stratum to break up.

Does Fluval Stratum Need To Be Replaced?

As above, Fluval appears to claim it will only last for up to 2 years, then presumably need replacing. I have yet to see this, so I would say no, it doesn’t need replacing unless it has broken down to a dusty mess.

Should You Gravel Vacuum Fluval Stratum?

No, you should not gravel vacuum your Fluval Stratum. The tumbling action of the Stratum in your gravel vac will cause the substrate to break up. Instead, just use a hose to siphon any debris off the surface of the Stratum, without getting too close, otherwise, the Stratum will disappear up the hose too.

Does Fluval Stratum Discolor The Aquarium Water?

No, Fluval Stratum doesn’t discolor the aquarium water. In fact, the Stratum actually helps reduce the discoloration from products like bogwood.

My Final Thoughts On Fluval Stratum

I have used Fluval Stratum in my 155 gallons for nearly 18 months at the point of writing. I chose it because I wanted a planted aquarium where the plants would thrive and it would look natural. I haven’t been disappointed. There are many good reasons to use Fluval Stratum including;

  • Easy for plants to root and grow in
  • It contains some of the micronutrients plants need to grow
  • It doesn’t affect water chemistry
  • It is a great substrate for shrimp, especially baby shrimp
  • It looks natural
  • Stratum can be costly
  • It does break down if you are too rough with it
  • It is lightweight, which can make it tricky to get plants to stay put until their roots grow into it

Having lived with Fluval Stratum in a large planted aquarium for 18 months, I would certainly use it again and I would recommend it to others. It looks great and it does what Fluval says it will.

About the Author

I’ve been keeping, breeding, and showing tropical fish for nearly 30 years. Over that time I’ve done it all! I’ve had great success and I’ve made some really foolish mistakes (like the time I bought an Asain Walking Catfish). Read more…
Richard James

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