12 Most Asked Questions about Substrates and Plants in an Aquarium (FAQs, Guide & More)

You’ll agree with us when we say that there are many resources online when it comes to the care of fish but not nearly enough when it comes to substrates and aquarium plants

That’s why we’re here to fill that void and answer some of the common questions many fish-keepers have regarding plants and substrates

In today’s post, we’ll be looking at the common questions and problems you might face when buying substrates and plants for your aquarium.

12 Most Asked Questions about Substrates and Plants in an Aquarium (Experts Answered)

1. How can I Ensure my Substrate is clean before I add it to my Fish Tank? 

Some substrates are advertised to be pre-washed but however, most substrates are often dusty and you’ll want to wash them thoroughly before using them otherwise they’ll turn your aquarium water very cloudy. 

As you can probably imagine, washing dusty gravel is messy and tedious work. The most common and efficient way to cleaning substrate is to place a few mugfuls into a clean bucket and spray water on it using a hose. 

As you’re spraying it with water, you should keep swirling the gravel around with your hand and then pouring the dirty water off until it eventually runs clear. You can then place this washed gravel into another bucket and then do the same with the next batch until all of your substrate is clean.

2. How much Gravel should I buy? 

This is actually harder to work out than most people expect it to be because of the confusing way it’s sold. Sand and gravel is sold in terms of weight whereas us fish-keepers are interested in the depth it will have in our fish tank

Commonly, people who use sand normally have a depth of about 1 inch whereas people who use gravel tend to have a deeper layer of about 2 inches or more. 

The weight of a liter of dry substrate can vary a lot. Fine sand usually weighs around 2 kg per litre whereas baked clay substrates can weigh as little as 1 kg per litre.

3. My pH Levels have risen after I added my Gravel, what should I do? 

You may have used gravel that is rich in Calcium and Magnesium. These are minerals that can integrate into your tank water and cause the pH to rise. 

A way to recognize this type of gravel is by their appearance. They are usually colored, textured and have a powdery coating. It is usually sold as a substrate for African Cichlids that prefer high pH water. 

If you have fish that don’t mind alkaline water such as Goldfish, this isn’t even a problem for you. However, if you have fish that prefer neutral or low pH water, you might want to change your substrate

4. What Diameter of Substrates should I go for?

It’s good if you can get the finest substrate that you can. These can often get expensive so you need to strike a balance between what’s affordable for you and best for your fish. 

Substrates that have a larger grain size tend to have larger gaps in between where dirt can get stuck. On the other hand, finer substrates don’t allow dirt to be trapped like this. Any debris or waste products in fine substrates comes up to the top where it can eventually be siphoned off by your fish tank filter.

5. Is it a good idea to use a mixture of Grain sizes? 

Yes, you can do this as it gives your gravel a very natural and rustic look. However, you should expect your larger grains to eventually rise to the top and then again, there’s the problem of dirt getting stuck between larger grain sizes that we discussed above.

6. How can I ensure my Substrate stays clean? 

The most efficient and easy way to keep your substrate clean is to use a gravel cleaner. We tested several varieties out and in our experience, the syphon-powered ones worked much better than the air and battery-powered ones.  

The syphon-powered gravel cleaner left our substrate with a pristine look with not a single piece of debris in sight. We vacuumed our gravel once a week for about two months and our aquarium always looked bright and clean with no signs of dust.

7. How do I tell if the Aquarium Plants I’m buying are fresh?

12 Most Asked Questions about Substrates and Plants in an Aquarium (Experts Answered)

The plants that are the healthiest have an abundance of leaves. Do not go for plants that have leaves with visible browning or torn leaves. You should also check the roots of the plants and ensure they are strong with no visible algae. 

8. Should I put my newly purchased Aquarium Plants into Quarantine? 

You may need to do this if the plants you bought are carrying new animals such as snails or freshwater polyps that you don’t want to get into your aquarium. In case you do end up with such plants, you might need to put them in a separate tank until you can clean them of these animals. To avoid this entirely, you might want to invest in plants that are sold in separate plastic containers that are ready to go and plant them straight into your aquarium.

9. What are some Things I should keep in mind when adding new Plants? 

First of all, you need to ensure that the roots of the plant are completely freed from the substrate it was sold in. 

It’s also a good idea to trim the roots slightly before planting them into your substrate as this will make them grasp your substrate more firmly. 

10. What are some fast-growing Aquarium Plants? 

There are many aquarium plants available that grow quickly. Some examples are: 

  • Green Cabomba
  • Southern Bacopa
  • Water Snowball 

11. My Plant’s leaves have holes in them, why is this? 

There could be several reasons behind holes in your plant’s leaves. You could have fish that like to feed on aquarium plants such as Catfish. This is characterised by leaves that only have their outer framework and nothing in between. 

If you have a plague of snails in your aquarium, this could also be the culprit. 

If none of the above are the case then you might want to consider the possibility that your aquarium plants are not getting sufficient nutrients such as nitrate or potassium. A simple analysis of your tank water can reveal whether this is the case or not. 

12. I’m noticing a black, slimy layer on my Plants, what is it and what can I do about it?

This is most likely due to a blue-green algae infestation. This is very annoying and harmful because not only will this stop your plants from photo-synthesising properly, it will also release many different toxins into your tank water that may harm your fish. 

The reason for this outbreak is usually due to an overabundance of nutrients in your water or due to unclean gravel. Properly maintaining water conditions and cleaning your substrate regularly can help you prevent this outbreak. 

If the outbreak has already occurred, you can try leaving your aquarium in darkness for a few days and then slowly changing your tank water little by little every day.


Many new fish-keepers focus a lot on their fish when starting their hobby without paying much heed to things like plants and substrates. 

It’s important to stress that being informed when it comes to substrates and plants for your aquarium is just as important and we hope we’ve provided you with sufficient information regarding these factors today. 

Let us know what substrates and plants you’re using. 

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