Fishkeeping vs Aquascaping: Why Water Change Needs Are So Different

When it comes to maintaining an aquarium, one of the most important — and often misunderstood tasks is water changing. While many assume all tanks require similar care, there’s a huge difference between traditional fishkeeping and aquascaping. Understanding this difference can save you from algae outbreaks, stressed fish, or a tank that’s constantly out of balance.

Let’s break down why aquascapes demand more frequent water changes and how this contrasts with the simpler needs of a fish-only tank.

What Is the Difference Between Fishkeeping and Aquascaping?

At first glance, a fish tank and an aquascape might look similar — water, substrate, some plants, and fish. But under the surface, these two setups operate very differently.

Fishkeeping is focused on maintaining healthy conditions for fish, often with minimal plants and a standard filtration system. These tanks typically don’t use added fertiliSers, CO₂, or high-intensity lighting. As a result, nutrient levels stay relatively stable, and waste mostly comes from the fish and uneaten food.

In contrast, aquascaping is a form of underwater gardening that is focused on pushing plant growth as far as you can for the best aesthetic. In “high-tech” setups, aquascapes often include strong lighting, injected CO₂, and a daily routine dosing of liquid or root fertilisers to encourage lush plant growth. This high-input environment significantly increases the biological load of the tank — and with it, the maintenance requirements.

Why Do Aquascapes Need Larger and More Frequent Water Changes?

Here’s the key issue: the same tools that fuel beautiful plant growth in aquascapes — light, CO₂, and nutrients — also create a perfect environment for algae and organic waste buildup if not properly balanced.

When plants are pushed to grow quickly under high light and CO₂ conditions, they naturally release organic compounds into the water. This includes decaying leaves, plant exudates, and even microbial byproducts from rapid root development. On top of that, daily or weekly fertiliser dosing adds macronutrients (like nitrogen and phosphorus) and micronutrients (like iron), which can accumulate in the water column.

If this excess is not removed through water changes, or taken up by plants,  it builds up over time, creating imbalances that can lead to algae blooms, cloudy water, and stressed livestock. This is why weekly 50% water changes are standard practice in high-tech aquascaping. In some cases , especially in densely planted or competition-style tanks, aquarists even change water multiple times per week.

Water changes in aquascaping are not just about removing waste. They're about resetting the nutrient levels and giving plants a clean, stable environment to thrive, as well as keeping a good environment for the live stock. Generally speaking, aquascapers don't overstock their tanks and live stock is usually kept to a minimum to complement the scape, not dominate it.

Fishkeeping: Simpler Needs, Less Frequent Water Changes

In a typical fish-only aquarium, there are no added fertilisers, no CO₂ injection, and usually lower-intensity lighting. That means far fewer variables to manage.

The main waste products come from fish metabolism — primarily ammonia — which is handled by beneficial bacteria in the filter. Once ammonia is converted to nitrite and then to nitrate, water changes are needed to keep nitrate levels in check. However, because there are no external nutrient inputs like fertiliser, the rate of nitrate buildup is much slower than in aquascapes.

As a result, small weekly water changes of roughly 20%-25% are usually enough to maintain good water quality in fish tanks. For lightly stocked tanks, even bi-weekly changes may be sufficient, provided water parameters are monitored.

That said, regular water testing is still essential. Even in a simple setup, nitrate levels, pH, and general hardness can drift over time. Performing small water changes consistently — and increasing them when needed — helps keep the system stable and your fish healthy.

Tailoring Water Changes to Your Aquarium Type

The frequency and volume of water changes shouldn’t be based on a “one size fits all” rule — they should be tailored to the type of tank you’re running.

• In fishkeeping, water changes are about removing accumulated waste. They can be smaller and less frequent, especially with good filtration and responsible feeding.

• In aquascaping, water changes are critical for managing excess nutrients, organics, and maintaining plant health in a high-input system. Larger, more frequent water changes are non-negotiable if you want to avoid algae and instability.

Whether you're keeping guppies in a beginner tank or maintaining a lush aquascape with carpeting plants and CO₂, your maintenance schedule should reflect your system's unique biology.

If you’re transitioning from traditional fishkeeping into aquascaping, one of the biggest mindset shifts is accepting that more inputs require more exports. The more you feed your plants — with light, CO₂, and nutrients — the more diligent you need to be with your water changes.

Aquascaping is rewarding, but it’s not “set and forget.” Mastering this balance is what separates thriving, algae-free tanks from those constantly battling problems.

Water Treatments

Remember to always dechlorinate your water when performing water changes, no matter how much you are changing.

The Importance of Dechlorinating Aquarium Water

When setting up or maintaining an aquarium, one of the most overlooked yet essential steps is dechlorinating tap water before adding it to the tank. Whether you're a beginner in fishkeeping or building a high-tech aquascape, skipping this step can lead to serious consequences for your aquatic life. What seems like a simple task is actually critical to the health and stability of your tank’s ecosystem.

Most municipal tap water is treated with chemicals like chlorine or chloramine to make it safe for human consumption. While effective for eliminating harmful bacteria in drinking water, these chemicals are toxic to fish, shrimp, snails, and even aquatic plants. Chlorine can cause severe gill damage in fish and kill off beneficial bacteria in your filter. Chloramine, which is a more stable combination of chlorine and ammonia, poses an even greater risk because it does not dissipate easily and continues to release toxic byproducts over time.

If untreated water is added to your tank, even in small amounts, it can lead to immediate fish stress or death, damage to plant roots, and the collapse of your tank's nitrogen cycle. The beneficial bacteria that handle ammonia and nitrite—critical for maintaining a healthy, cycled aquarium—are particularly sensitive to chlorine and chloramine. Once these bacteria are damaged or destroyed, your tank can experience dangerous spikes in toxic waste compounds, endangering all inhabitants.

Fortunately, dechlorinating your water is simple and fast. The most effective way is by using a liquid water conditioner such as Seachem Prime, NT Labs Optimus or similar products. These treatments instantly neutralise chlorine and break down chloramine, rendering the water safe for use in your aquarium. It’s important to dose the conditioner based on the volume of new water being added, not the total volume of your tank. This ensures the full neutralisation of harmful chemicals in the replacement water.

Some aquarists choose to let tap water sit for 24 to 48 hours in an open container to allow chlorine to dissipate naturally. However, this method only works if your tap water contains chlorine—not chloramine, which is more common in modern water treatment and does not evaporate. Because of this, using a water conditioner remains the safest and most reliable option for any setup.

In aquascaping, especially in CO₂-injected, high-light planted tanks, the importance of dechlorinated water is even greater. Sensitive plant species can suffer from root burn or inhibited nutrient uptake if exposed to chlorine or chloramine. Additionally, many aquascapes include delicate invertebrates like shrimp and snails, which are far more vulnerable to trace chemical residues. Regular large water changes in these systems make consistent dechlorination a must to maintain balance and prevent algae issues.

Ultimately, dechlorinating your water should become second nature in your aquarium care routine. It protects your fish, plants, and filter bacteria, and helps maintain a stable, healthy aquatic environment. It takes only a few seconds, costs very little given how little you use, and can prevent a host of avoidable problems.