How to start a planted aquarium? 5 beginner mistakes to avoid!

Planning to start a planted aquarium? It can be exciting, fun, and sometimes a bit overwhelming. I definitely still remember buying my very first tank.

But you’re probably dealing with a lot of questions right now:

• How to start a planted aquarium?
• What is the best beginner planted aquarium setup?
• And which mistakes should you absolutely avoid?

When I started my planted aquarium, I made just about every mistake you can imagine. I’m still a bit embarrassed about it, ha ha! Luckily, that actually works in your favor, because now I can tell you exactly what you should NOT do. Of course, I can’t list every possible mistake you might make when starting a planted tank, but these are the most common beginner mistakes. Each time, I explain what goes wrong and how to handle it the right way.

Good luck with your new tank!

Mistake 1 when you start a planted aquarium: a “small but nice tank”

Cute, those nano tanks, right? But honestly … I’d wait a bit before going that route. Why? A small tank is not easier to maintain, quite the opposite. A small aquarium literally and figuratively gives you very little room for mistakes.

In other words, you really need to know what you’re doing. One small misjudgment and the balance in your planted aquarium is gone. A small tank has hardly any room for extra fish or plants; everything has to be exactly right.

So what’s better if you plan to start a planted tank as a beginner? Buy an aquarium with at least a volume of 100 liters. Yes, it costs a bit more than that small aquarium you first had in mind, but it gives you room to grow in the hobby as an aquascaper. It also makes your planted tank more stable and less sensitive to mistakes. Once you’ve built up experience, you can always go for that nano tank later.

Mistake 2 when starting a planted tank: “water is water”

Unfortunately … one type of water is not the same as another. And that has consequences for both your fish and your plants. If you want to keep a cichlid aquarium, for example, the water will have a very different composition than a South American biotope.

So, when planning to start a planted aquarium, first think about which aquarium style you want, and which fish and plants you want to keep. Then check which water values those fish and plants need for the style you have in mind. Only then should you start your planted tank setup steps.

Mistake 3 by aquarium beginners: adding too many fish, too fast

Your aquarium is an ecosystem in itself. At least, you need to give it a few weeks so everything can settle into balance. You do this by letting your tank run for a few weeks without fish until your planted aquarium has stable values.

This easily takes 4 weeks. Only then is it time for the first fish. Also, don’t add too many fish at once. Start with one small group and wait at least a week before adding the next group. That way, your fish can settle in, and the bacterial culture can adapt to the new stocking.

Think ahead as well. How big will the fish in your planted aquarium get? Fish need space to swim, and not all fish and shrimp are compatible. Keep this in mind before you go to the store.

Beginner mistake 4: using very strong light right away

I see it happen all the time: using very strong light right away, preferably for 10 hours straight. Yes, your plants will grow faster with stronger light. But remember: the faster the plant growth, the more CO2 & plant fertilizers you need to add. If those conditions are not met, plant growth stops, or even worse … algae appear.

Especially thread algae and black beard algae show up very quickly with strong light combined with too little CO2.

My advice: dim the light during the first weeks with a dimmer or floating plants and limit the lighting time to 6 hours. Then, each week, add half an hour until you reach a total of 8 hours. After that, you can carefully increase the light intensity as well as the CO2 and plant fertilizers. This slower approach keeps everything more balanced and reduces the risk of algae.

Mistake 5: an aquarium filter that is far too weak

This is actually partly the aquarium manufacturer’s fault. Very often, free filters are included with aquarium sets. That’s nice, because you have everything you need to start right away. Unfortunately, those filters are often cheaped out on and have pumps with a weak “flow rate” (liters per hour).

The result of a weak filter? A lot of waste remains in the tank, and nutrients don’t reach your plants properly, causing poor growth. My tip: remove the standard filter and go straight for a good external canister filter, as an essential part of your planted aquarium equipment list. Choose a filter with a flow rate that filters the volume of the tank at least 5 times per hour. So, if you have a 100-liter aquarium, I recommend a filter with a minimum flow rate of 500 liters per hour.

A few extra tips on how to start a planted aquarium

Besides these 5 beginner mistakes, I’ll share a few tips that have their place in a planted aquarium beginner guide:

• Don’t overfeed your fish; it’s enough to give a small amount once a day.
• Think about aquarium maintenance and water changes, even during the startup phase.
• Feel free to use a bacterial supplement to speed up filter startup, but still account for the nitrite spike.
• At the beginning, plants will melt; this is normal because most plants are grown above water and are now adapting to their submerged form. Trim damaged leaves occasionally, but otherwise leave the plants alone. Don’t forget your plant fertilizer.

Conclusion

Starting a planted tank is awesome if you take the time to read up on it beforehand and follow these tips. Do you still have questions about how to start a planted aquarium? Feel free to ask them below or by email.

In the end, it’s much better to prevent problems than to fix them afterward. Starting a planted aquarium should first and foremost be beautiful and fun, and I’m happy to help with that!