With Real Science, Target Parameters & Correction Strategies By ProHobby™ | Delhi NCR’s Science-First Aquarium Specialists
🌊 Why Water Chemistry Determines 90% of Aquarium Success
Every fish, shrimp, snail, plant, and coral relies on one biological truth:
If water chemistry is unstable, the organism’s internal osmotic pressure collapses — causing stress, disease, or death.
Water chemistry affects:
- Cortisol levels & systemic stress
- Gill oxygen exchange
- Immune system strength
- Nitrification efficiency
- Plant nutrient uptake
- Coral calcification
- Ammonia toxicity
- Algae pressure
This guide breaks down the real chemistry behind healthy aquariums, with Delhi NCR–specific adjustments and cross-environment coverage (freshwater, brackish, marine, biotope).
SECTION 1 — Core Water Chemistry Parameters (Explained Scientifically)
1. pH — Power of Hydrogen
Controls acidity/alkalinity and shifts ammonia toxicity.
- High pH → more toxic NH₃ (ammonia gas)
- Low pH → more NH₄⁺ (less toxic ammonium)
Chemical equilibrium:
NH₄⁺ ↔ NH₃ + H⁺
Shifted strongly by pH and temperature.
2. KH — Carbonate Hardness (Buffering Capacity)
Prevents sudden pH swings caused by:
- CO₂ injection
- Plant respiration cycles
- Organic acid buildup
- Water changes
Low KH = risk of pH crash.
3. GH — General Hardness (Calcium & Magnesium)
Controls:
- Nerve signalling
- Bone & shell formation
- Osmoregulation
- Plant cell structure
- Ca:Mg nutrient ratios (ideal 3:1)
4. TDS — Total Dissolved Solids
Indicates total ion load.
High TDS increases osmotic pressure → fish lose water internally.
Low TDS reduces osmotic pressure → fish swell (water rushes into cells).
5. Salinity (Marine & Brackish)
Defines osmotic environment for:
- Marine fish
- Brackish fish
- Corals
- Invertebrates
Marine = high ionic environment
Freshwater = very low ionic environment
Brackish = dynamic transition zone
6. Alkalinity (Marine KH)
Critical for reef aquariums.
Corals use alkalinity + calcium to build skeletons:
Ca²⁺ + 2HCO₃⁻ → CaCO₃ + CO₂ + H₂O
7. CO₂ (Planted Aquariums)
How CO₂ influences pH and overall planted tank stability?
- pH (CO₂ forms carbonic acid)
- Plant photosynthesis
- Nutrient demand
- KH usage
SECTION 2 — Target Water Chemistry Ranges by Aquarium Type
A) Freshwater Community & Planted Tanks
| Parameter | Target Range |
|---|---|
| pH | 6.5–7.2 |
| KH | 2–6 dKH |
| GH | 4–8 dGH |
| TDS | 120–180 ppm |
| CO₂ | 20–35 ppm |
Ca:Mg ratio:
Ideal = 3:1
Common problem in Delhi = Ca-heavy water → Mg deficiency → stunted plants.
B) African Cichlid Hardwater Systems
| Parameter | Target |
|---|---|
| pH | 7.8–8.4 |
| KH | 8–14 dKH |
| GH | 10–18 dGH |
| TDS | 200–350 ppm |
C) Brackish Aquariums*
| Type | Salinity (SG) |
|---|---|
| Low | 1.003–1.008 |
| Mid | 1.008–1.016 |
| High | 1.016–1.022 |
Stable KH is essential: 6–10 dKH. *see complete brackish aquarium setup and care guide
D) Marine & Reef Tanks*
| Parameter | Ideal Range |
|---|---|
| Salinity | 1.025–1.026 |
| pH | 8.1–8.4 |
| Alkalinity | 7–9 dKH |
| Calcium | 400–450 ppm |
| Magnesium | 1250–1400 ppm |
| Nitrate | <10 ppm |
| Phosphate | 0.02–0.08 ppm |
*see foundational marine aquarium setup guide
SECTION 3 — Delhi NCR Water Chemistry (Critical Local Notes)
Typical municipal/bore water across NCR:
- pH: 7.6–8.5
- KH: 6–12 dKH
- GH: 10–16 dGH
- TDS: 300–600 ppm
Problems this creates:
- Too hard for most tropical species
- Ca:Mg imbalance → poor plant growth
- CO₂ pH instability in planted tanks
- Higher ammonia toxicity at high pH
- Boiler-scale deposits on glass, heaters & filters
Ideal solution:
✔ RO/DI + controlled remineralisation
✔ Adjust GH/KH ratios correctly
✔ Match water to livestock origins (Amazon, Africa, Reef, Brackish)
SECTION 4 — Maximum Safe Rate of Change (Very Important)
| Parameter | Max Daily Change |
|---|---|
| pH | ≤ 0.3 units |
| KH | ≤ 1–2 dKH |
| GH | ≤ 2–3 dGH |
| TDS | ≤ 10% |
| Salinity | ≤ 0.002 SG |
Never chase numbers. Aim for slow corrections only.
SECTION 5 — Osmoregulation Science (Why Fish Die After “Simple” Water Changes)
Freshwater Fish
Internal ion concentration > water
→ Water rushes in → swelling risk
Marine Fish
Water > internal concentration
→ Water rushes out → dehydration risk
Brackish Fish
Most sensitive because they regulate both directions.
Signs of osmotic distress:
- Gasping
- Clamped fins
- Excess slime
- Flashing
- Post–water change deaths within 24 hours
SECTION 6 — Testing Accuracy (What Actually Works)
| Method | Reliability |
|---|---|
| Test Strips | ❌ Inaccurate |
| Liquid Kits | ✔ Moderate |
| TDS Meter | ✔ Exact |
| pH/ORP/Salinity Digital Probes | ✔ Very high |
| ICP-OES (Marine) | ✔ Laboratory-grade |
ProHobby™ offers professional water testing, including advanced reef diagnostics.
SECTION 7 — Troubleshooting Table
| Symptom | Cause | Solution |
|---|---|---|
| pH crash | Low KH | Add KH buffer |
| Hard water scaling | High GH | Use RO blend |
| Coral tip burn | Alk swing | Dose alk daily |
| Plant melt | High KH + unstable CO₂ | Lower KH + stable CO₂ |
| Fish gasping after water change | Osmotic shock | Reduce TDS swing |
Conclusion
Water chemistry directly determines:
- Disease resistance
- Stress reduction
- Plant & coral growth
- Filtration performance
- Algae prevention
- Livestock lifespan
“Water chemistry is the life-support system of an aquarium. Everything else is secondary”.
ProHobby™ provides Delhi NCR–specific water correction plans, remineralisation recipes, and testing services.
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