Using Fluval Stratum With Houseplants

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The newest houseplant craze is using Fluval stratum with our houseplants in a semi hydroponic setup. Is Fluval stratum for indoor plants worth all the fuss? Let’s take a look at how the Fluval stratum stands up against other semi hydroponic houseplant systems.

If you are new to this blog my name is Ashley and I am a soil scientist. I am located in a Canadian Zone 3 and a USDA Zone 4. I write articles, make YouTube videos, Instagram & Facebook posts all designed for Canadians and Cold Climate gardeners using science-based methods. If you are looking for anything specific be sure to let me know in the comments down below.

What is Fluval stratum?

The Fluval stratum is compressed balls of volcanic soil. The fact that it is soil makes it drastically different than a volcanic rock (pumice, lechuza pon mix) and even LECA. This soil is incredibly lightweight and naturally contains plant essential nutrients such as potassium, phosphorus and iron. But it doesn’t necessarily contain all 17 that would be needed to achieve proper plant growth.

This lightweight volcanic soil is porous in ways that allow for nutrient cycling microbes to find a happy zero to hang out in. This is similar to that of our regular potting soils in that microbes are used for phosphate solubilization and nitrogen cycling. This is incredibly valuable for keeping clear water in their intended application, fish tanks. However, our houseplants can also benefit from these unique properties.

Grab You Fluval Stratum For Houseplants Here.

What Makes Fluval Stratum Work So Well With Houseplants?

The secret ingredient as to why Fluval stratum can grow houseplants so effectively is the ability to slightly acidify the pH. Having a pH that is below 7 and between 6 and 6.5 is ideal for plant nutrient uptake. Fluval Stratum is able to alter not only the growing medium pH but also the surrounding water pH as well.

Our houseplant potting soil is generally pretty acidic and has the opposite issue of many semi hydro Lechuza or LECA setups. Our potting soil acidity is caused by the natural disposition of peat-based soil. This means without a lime addition we tend to restrict our plant nutrient uptakes. This can limit our plant’s growth and open the plant up for disease and pests.

With Semihydro LECA we tend to see a more alkaline medium, which again can cause nutrient deficiency. With LECA or a semi hydro system, this is much easier to correct. I have an entire video and blog post about making these adjustments using fertilizer and pH up/down.

With the Fluval stratum having a higher Cation ion exchange capacity we tend to see both acidic and alkaline water additions to be neutralized. If you are looking to use Fluval stratum in combination with fertilizers you may want to still neutralize the pH or set it appropriately to maximize results.

 Remember Fluval stratum is not coated in a slow-release like lechuza and does not contain nitrogen. The intended purpose of this medium is for fish tanks which have their own nitrogen cycle and do not typically need nitrogen additions.

Do You Use Fertilizer With Fluval Stratum?

This is completely up to you and your preference. If you choose to use fertilizer you will see rapid growth and an overall healthier houseplant. The stratum medium does not have any synthetic fertilizer just the natural components. This means we do not need to worry about burning our plants when using a synthetic compound.

Keep in mind Fluval stratum is missing a key competent to plant growth, nitrogen. This is by design because fish tanks are sensitive to the influx of nitrogen. Using supplemental nitrogen in particular is going to be key for proper plant growth.

I recommend you follow my guide for fertilizing semi hydro to see the best results.

Does Fluval stratum work for houseplants?

Yes, Fluval stratum will work for houseplants & you will likely see incredible results compared to your LECA setup. This is because a vast majority of LECA and semi hydroponic houseplant people are fertilizing their plants incorrectly.

With houseplants in Fluval stratum, we will preserve stellar results without the additions of fertilizer due to the nature of the product. To maximize this we want to also add fertilizers correctly.

Should You Rinse Your Fluval Stratum Before Planting Your Houseplants

Yes, but be careful! Fluval stratum is very delicate. It’s the equivalent of a heavy clay being rolled into small balls. Use gentle cold water inside a colander and avoid handling to product whenever possible. If your semi hydro setup is not in a clear container you can skip this process altogether. It is simply for visual appearances only and rinsing doesn’t lend any other benefit. 

What Should You Replace Your Fluval Stratum?

Fluval stratum will degrade over time and as mechanical manipulation takes place. The general rule of thumb is 1-2 years. Keep in mind you can simply top up the stratum and do not need to simply through it out. The stratum itself should not become overly saline as we see with leca. If you do see salt build-up you may want to consider a quick rinse.

How To Use Fluval Stratum With Houseplants

When it comes to using Fluval stratum with houseplants we want to take into consideration the amount we need, how to repot & even how to mix with other mediums.

Amount Of Fluval Stratum Needed For A Houseplant.

Fluval stratum is incredibly expensive when compared to LECA or other potting mediums. This is why the amount you need being perfect is much needed for saving some cash. FS (fluval stratum) is a very lightweight item that will not support larger plants with ease. But filling the entire vessel with Fluval stratum will cost you a lot of cash.

The happy medium is somewhere in the middle. You want to have the roots covered with Fluval stratum whenever possible but any form of stem/stalk to be covered with something that has more weight like LECA, rocks or pea gravel. Keep in mind again that the product is fragile so you need to place the “weight” and leave it.

Can You Mix LECA or Pumice With Fluval Stratum?

Yes, and I highly advise you do so if you want to run more water in the setup. If you want to fully saturate the area with water and not risk root rot, you want to add LECA or Pumice. The LECA and pumice can be a source of oxygen and help prevent an anaerobic environment. 

Using LECA or Pumice with Fluval stratum also will mean cost savings. The ratio you use should be 50/50 whenever possible again with the being in the root zone only. For holding larger plants in place again try adding rocks on top. When you use a combo or FS and LECA we typically see less damage to the FS. This is because the LECA adds support to the entire system.

How Much Water Do You Using When Potting Up Houseplants In Fluval Stratum?

If you are using a straight Fluval stratum you want to be able to see air spaces in the medium. This is why you should always pot up into a clear container. If you are using a mix of LECA or pumice and Fluval stratum you can simply fill it with water entirely.

Let me know in the comments below what else you would like to learn about the Fluval stratum for growing houseplants.

Fluval Stratum For Houseplants
Fluval Stratum For Houseplants