Keeping Your KH Steady

Simple Ways to Protect Your Water’s “Bodyguard”

In the GH/KH/TDS article, we called KH the bodyguard of your water.

KH (carbonate hardness) is the buffer that helps pH stay stable.
When KH is too low, pH can swing around more easily. When it’s in a comfortable range, your fish and shrimp usually have a calmer life.

If you’re still new to what GH, KH, and TDS actually mean, you can read my earlier post on three water numbers that quietly shape your tank.

So the next questions are:

“How do I keep KH steady?”
“And what if I want a more natural, low-water-change tank?”

This guide focuses on practical ways to maintain and gently increase KH, especially with normal tap water, shrimp, and plants.

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1. First Step: Know Your KH and pH

You don’t need a lab. A simple liquid test kit is enough.

• KH test – shows how many °dKH you have

• pH test – shows how acidic or alkaline your water is

For most Neocaridina + easy plants:

• KH around 2–6 dKH is usually workable

• pH around 6.5–7.5 is generally fine

We don’t chase perfect numbers. We want stable, reasonable numbers that don’t move around too much.

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2. How KH Normally Changes in a Tank

KH can slowly go down over time.

Things that use up KH:

• Normal bacteria activity and organic breakdown

• Leaves, driftwood, and “humic” materials

• Active soil that gently pulls pH down

• Adding very soft water (rain/RO) without remineralising

If you still do weekly water changes with tap water that has some KH, your tank often “resets” itself and KH stays similar.

If you’re aiming for a more natural, low-change tank, we handle KH in a different way (we’ll come to that in Section 5).

If you like humic layers and leaf litter, you can still use them – I explain how in my post on creating a balanced aquarium with humic layers.

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3. For Regular Water-Change Tanks: Let Tap Water Help

If your tap water has decent KH, you may not need special products at all.

Simple routine:

1. Test your tap KH once or twice.

2. Test your tank KH before a water change.

3. Do 20–30% weekly water changes with treated tap water.

If tap KH and tank KH look similar over a few weeks, your KH is already being maintained by this pattern. In that case, focus on:

• Treating tap water (dechlorinator, temperature match).

• Avoiding huge 70–80% changes that shock the tank.

• Not mixing many different water sources randomly.

If tap KH is very low, or your tank slowly eats it down, that’s when we think about raising KH gently.

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4. Ways to Gently Raise KH (for Any Tank)

These methods work for both “normal” and “low-change” tanks. The difference is how fast you use them.

4.1 KH Buffer / Alkalinity Powder

Many brands sell “KH buffer” or “alkalinity up”, usually based on bicarbonates.

Basic idea:

1. Prepare a bucket of new water.

2. Add dechlorinator.

3. Add a small measured amount of KH buffer (start lower than the label).

4. Stir and test KH.

5. Use this water for your tank.

Good because:

• You adjust new water, not the whole tank at once.

• Easy to repeat the same dose weekly.

Still, avoid raising KH more than 1–2 dKH per day.

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4.2 Baking Soda (DIY, Use Slowly)

Baking soda (sodium bicarbonate) is a DIY KH booster.
It works, but it’s strong and fast.

If you ever use it:

• Dissolve in a separate bucket, never sprinkle into the tank.

• Add tiny amounts, test, and aim for a small KH increase.

• Use that adjusted water for changes or top-ups.

For most people, a commercial buffer with clear instructions is calmer and safer.

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4.3 Crushed Coral, Limestone, or Aragonite

These materials slowly release carbonates and raise KH (and GH):

• Crushed coral

• Limestone chips

• Aragonite sand

How to use:

• Put a small bag of it in the filter, or

• Mix a little in one corner of the substrate.

They dissolve slowly, which suits a natural or low-change style.
But they can overshoot if you put too much, so start small and test.

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4.4 Remineralising Salts (GH/KH+)

If you ever work with RO, distilled, or rainwater, you’ll need to add minerals back.

Remineralising salts are mixed into pure water to:

• Raise GH and KH

• Reach a target TDS

This gives the most control but also needs more testing and patience.
For a pure tap-water keeper, it’s optional.

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5. What If You Aim for a “No Water Change” Natural Tank?

In our natural shrimp tank idea, the long-term goal is:

• Deep, mature substrate

• Plants, leaves, and biofilm doing most of the work

• Very low or almost no water changes

Here, we can’t rely on weekly resets.
So we support KH in different ways.

5.1 Start With the Right Base

If your tap water KH is already moderate (for example 3–5 dKH), you may not need extra KH at all for a natural tank. The system will slowly find its own balance.

If your KH is very low (0–1 dKH) and you still want a near no-change style, it helps to:

• Add a small bag of crushed coral or similar in the filter, or

• Mix a little into the bottom layer of the filter area.

It will dissolve slowly and act like a quiet KH “battery” in the background.

5.2 Think in “Top-Ups”, Not Big Changes

Even “no water change” tanks still lose water by evaporation.

When you top up:

• Prefer treated tap water (if your tap has some KH), or

• RO + a tiny amount of remineralising salts if you’re building water from zero.

These top-ups bring in a little KH and GH over time without big swings, especially if you only remove small amounts of liquid during maintenance.

5.3 Let the System Tell You When to Intervene

In a healthy natural tank:

• pH might sit a bit lower, but

• It stays stable, and

• Shrimp and fish behave normally.

If KH drifts very low (0–1 dKH) and you see:

• pH dropping more and more, or

• Animals stressed with no other clear cause,

then even in a natural setup it’s okay to:

• Do one or two small partial water changes (for example 10–15%), with slightly higher-KH water, or

• Add a very small amount of crushed coral and wait.

The spirit of the method stays the same: small moves, long pauses.

This is the same idea I use in my natural Neocaridina shrimp tank with plants and leaves, where the goal is slow, stable water instead of big weekly resets.

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6. Everyday Habits That Help KH in Any Style

Whether you like weekly changes or a natural deep substrate, these habits help KH stay friendly:

• Keep your water source consistent.

• Avoid sudden, big changes in pH or KH.

• Test KH and pH once in a while, especially if something feels “off”.

• Add any KH-raising material slowly and then leave it alone for a few weeks.

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7. The Main Idea

If GH is the mineral “food” and TDS is the weight of everything in the water, KH is still the bodyguard that stops pH from getting pushed around too easily.

You can protect that bodyguard in two main ways:

• In a regular water-change tank: let treated tap water and gentle buffers do the work.

• In a natural / low-change tank: build KH support into the system itself (substrate, crushed coral, remineralised top-ups) and make changes slowly.

You don’t need perfect numbers or complicated chemistry.
With a few calm habits, KH can quietly do its job in the background while your shrimp, fish, and plants live their slow, stable, natural life.