Why Is My pH Rising in a Shrimp Tank? (Causes & Fixes)

Seeing your pH climb over 6.8–7.0 in a Caridina shrimp tank? That’s a red flag. These shrimp need acidic, stable water in the 5.8–6.6 range — and if your buffering system fails, your pH can rise fast. Here’s why it happens, how to test for it, and what to do next.

📈 Signs Your pH Is Rising

• Digital pH pen shows 7.0 or higher
• Shrimp hiding or failing molts
• Increased algae growth or surface film
• Old active substrate (8+ months)

⚠️ What Causes pH to Rise in Shrimp Tanks?

• Substrate exhaustion: Active substrates like ADA Amazonia or Fluval Stratum lose buffering over time
• KH buildup from top-offs: Topping off with tap or KH+ adds carbonate hardness, raising pH slowly
• Old remineralizer: Dosing KH+ or mixed salts by mistake instead of GH-only
• Crushed coral or shells: Anything calcareous will dissolve and raise pH

🧪 How to Test for the Root Problem

• Test pH with a calibrated digital pen (not strips)
• Check KH — if over 1 dKH, buffering is likely compromised
• Test TDS — rising TDS without water changes can mean KH creep

🛠️ Safe Fixes for a Rising pH

• Switch to RO water only — and remineralize with GH+ only
• Replace your buffering substrate if it’s over 8–12 months old
• Add Indian almond leaves or alder cones to gently lower pH
• Perform small water changes (10–15%) every few days with corrected water

💡 Prevention Tips

• Never top off with untreated tap or RO-only water
• Always use a GH-only remineralizer (no KH)
• Replace active substrate on schedule (or rotate slowly)
• Test pH, KH, and TDS weekly — track trends

🔗 Related Water Chemistry Guides

• How to Test GH & TDS the Right Way
• Remineralizing RO Water for Shrimp
• When to Replace Substrate (Without Crashing Your Tank)

If your pH keeps creeping up, post your water parameters in the comments and I’ll help you figure out where it’s going wrong.