Understanding KH, pH, and Buffering in Shrimp Tanks (Complete Shrimp-Safe Guide)

If you’re keeping shrimp—especially Caridina—understanding KH, pH, and buffering is the difference between stable water and total disaster. These three factors work together to control how stable your tank’s acidity stays over time.

Table of Contents

• What Is KH (Carbonate Hardness)?
• How KH Affects pH
• Why Caridina Shrimp Need Low KH
• How Active Substrates Buffer pH
• What Causes pH Crashes (and How to Prevent Them)
• Safe Ranges for pH and KH (Caridina vs. Neocaridina)

What Is KH (Carbonate Hardness)?

KH (carbonate hardness) is the measure of dissolved carbonates and bicarbonates in your water. These act as a buffer, keeping your pH from swinging too far in either direction.

• High KH = high buffering capacity → pH stays stable but harder to adjust
• Low KH = low buffering → pH changes more easily

KH is measured in degrees (dKH) or ppm (1 dKH ≈ 17.9 ppm).

How KH Affects pH

KH directly stabilizes pH. The more KH you have, the more resistant your water is to changes in acidity. But that’s not always good in a shrimp tank.

• High KH (5–8+): pH will stay around 7.6–8.0 and resist acidic buffering
• Low KH (0–2): pH can drop to 6.5 or lower, ideal for softwater shrimp

Warning: If you try to lower pH without adjusting KH, the change won’t stick—or worse, crash suddenly.

Why Caridina Shrimp Need Low KH

Caridina shrimp (like Crystal Reds, Taiwan Bees) come from softwater environments with nearly zero KH. They don’t tolerate carbonate-based buffering or alkaline pH levels well.

• Target KH: 0–1 dKH
• Target pH: 5.8–6.4

Low KH allows active substrate to naturally lower and maintain pH where Caridina thrive. High KH will cancel out that effect and raise pH dangerously for them.

How Active Substrates Buffer pH

Active substrates (like ADA Amazonia, SL-Aqua, Brightwell) are designed to lower and stabilize pH by absorbing KH. This buffering effect only works in **low-KH environments**.

• They pull carbonates out of water, dropping pH into the 5.8–6.4 range
• They wear out over time (~12–18 months)
• Adding KH back into the system defeats the substrate’s purpose

Pro Tip: Always use RO water with remineralized GH+ (no KH) to preserve substrate function.

What Causes pH Crashes (and How to Prevent Them)

• Overfeeding = waste = acid-producing bacteria = pH drop
• Depleted buffering (KH near 0) = no resistance to change
• No water changes = TDS rise = system instability
• Expired active substrate = no buffering left

Prevention tips:

• Use only RO + GH+ remineralized water (0 KH)
• Monitor pH weekly with a digital tester
• Replace active substrate every 12–18 months
• Do regular small water changes to reset organic load

Safe Ranges for pH and KH (Caridina vs. Neocaridina)

Final Thoughts

Understanding how KH and pH interact is critical if you’re breeding shrimp—especially Caridina. Use RO water, eliminate KH, and let your substrate do the work. Regular testing and stable dosing = long-term shrimp success.

Still unsure about your water chemistry? Drop your TDS, GH, KH, and pH readings in the comments, and I’ll help you troubleshoot your setup.