How to Do a Water Change Without Stressing Your Fish

How to Do a Water Change Without Stressing Your Fish

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No one wants their fish to panic every time you bring out the bucket. But water changes don’t have to be stressful (for you or your fish) In this guide, we’ll walk you through the steps to make water changes smooth, safe, and stress-free, while keeping your tank sparkling and your fish feeling fine.

BEST PRACTICES FOR PERFORMING WATER CHANGES

 

TOOLS YOU'LL NEED:

GRAVEL VACCUM OR SIPHON TUBE

 

BUCKET OR CONTAINER (USE ONE ONLY  FOR AQAURIUM USE!)

 

DECHLORINATOR OR WATER CONDITIONER (LIKE SEACHEM PRIME)

 

WATER TEST KIT (LIQUID IS BETTER THAN STRIPS!)

 

FRESH WATER (TAP OR RO/DISTILLED)

STEP BY STEP GUIDE

 

1. TEST YOUR WATER

 

Use your test kit to check ammonia, nitrite, nitrate, and pH levels. This tells you how urgent a water change might be.

 

YOU WANT 0 PPM AMMONIA, 0 PPM NITRITE, AND FOR NITRATES, WELL, THAT DEPENDS ON THE FISH!

 

HERE ARE SOME GENERAL NITRATE GUIDELINES:

 

Species Ideal Nitrate Range (ppm)
Betta Fish Under 2.5 ppm
Goldfish Under 20–40 ppm
Discus Under 10 ppm
Panda Corydoras Under 10 ppm
Livebearers (e.g., Guppies, Mollies) Under 20 ppm
Tetras & Rasboras Under 20 ppm
African Cichlids Under 40 ppm



Perky Tip!

 

If your nitrates are always reading zero, it could be because you’ve got lots of live plants doing the heavy lifting. That’s a great sign, but still test regularly to make sure things stay stable! 


 

2. PREPARE YOUR NEW WATER



Seachem Prime Water Conditioner  
  • Use a dechlorinator (like Seachem Prime) if you’re using tap water (this removes chlorine and chloramine).
  • Let the treated water sit until it’s the same temperature as your tank.
  • If using RO or distilled, make sure you remineralize if your species requires it.

 

 

 

3. REMOVE OLD WATER

 

Use your siphon to gently remove the old tank water.

 

About 10–30% is a very rough guideline.

 

How much you remove depends on a few things: your tank size, how heavily it’s stocked, whether you have live plants, how stable your water parameters are, and what your latest test results show.

 

If your nitrates are creeping higher than your species prefers, or if ammonia or nitrite levels are anything but zero, it’s time for a more generous water change.

 

A lightly stocked planted tank might only need 10%, while a busier, smaller tank might need closer to 30%.

 

Perky Tip!

 

Try not to stir up too much debris, especially if you have sand (hello, cloud-fest).

 

 

 

4. CLEAN YOUR SUBTRATE (OPTIONAL)

 

While siphoning, hover over the substrate to remove trapped waste.

 

Don’t stir up every inch, just focus on visibly dirty areas.

 

If you’re using sand as your substrate, it’s especially important to give it an occasional gentle stir to prevent harmful anaerobic gas pockets from forming underneath.

 

A light swirl here and there during cleaning can help keep things safe and fresh below the surface.

 

5. ADD NEW WATER GENTLY

 

Panda Corys  

Pour slowly or use a drip method to avoid shocking your fish.

 

The drip method is a gentle way of adding new water, using airline tubing with a valve, or even a small cup over time, to let the temperature and water chemistry adjust slowly.

 

It takes a bit longer, but it’s super gentle on your fish and your aquascape.

 
     

WHY BOTHER?

 

Because pouring too fast, especially from above, can blast a crater in your substrate, launching gravel or sand across the tank like a mini explosion.

 

And when that debris lands on your plants? It’s the worst.

 

It can smother delicate leaves or even knock roots loose. 

 

Perky Tip!

 

Never pour water directly on your fish. Aim for a hardscape item or use a clean plate, lid, or even your hand to break the flow. Your tank (and your plants) will thank you.

 

 

 

6. TEST AGAIN

 

After refilling, do a quick water test to ensure everything’s in range.

 

Perky Tip!

 

Acclimating the new water’s temperature and pH is more important than chasing exact numbers. Stability is what really matters!

 

 

 

TIPS TO MINIMIZE STRESS ON YOUR FISH

 

KEEP THE LIGHTS LOW OR OFF DURING THE CHANGE

 

AVOID LOUD NOISES AND SUDDEN MOVEMENTS

 

DON’T OVER-CLEAN. PRESERVE BENEFICIAL BACTERIA BY CLEANING ONLY WHAT’S NEEDED

 

STICK TO A ROUTINE SO YOUR FISH KNOW WHAT TO EXPECT

 

 


SHOULD YOU USE CHEMICAL FILTRATION?

Carbon filtration

Chemical filtration can be a helpful backup!

 

Here’s the lowdown:

 

  • Activated Carbon: Absorbs odors, discoloration, and some toxins.
  • Ion Exchange Resins: Reduce water hardness by swapping minerals.

 

These are great extras, but don’t rely on them to replace regular water changes. Think of them like a Brita filter: nice to have, but not a deep clean.

 

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