Always in this order: (1) total alkalinity first — target 80-120 ppm, adjust with sodium bicarbonate (raise) or muriatic acid/sodium bisulfate (lower), (2) pH second — target 7.2-7.8, adjust with soda ash (raise) or sodium bisulfate (lower), (3) calcium hardness last — target 200-400 ppm, adjust with calcium chloride (raise) or partial drain (lower). Never adjust pH before TA is in range.
Pool water balancing has a correct sequence that most guides skip. Total alkalinity is the buffer that makes pH stable. If you adjust pH before setting alkalinity correctly, your pH will keep drifting back out of range and you will spend the season chasing it. Set TA first, then pH, then calcium — in that order every time.
The Correct Adjustment Order and Why It Matters
| Step | Parameter | Target Range | Why This Order |
| 1 | Total Alkalinity (TA) | 80-120 ppm | TA is the pH buffer. Without correct TA, pH is unstable and any pH adjustment drifts quickly. Fix this first or you will be chasing pH all season. |
| 2 | pH | 7.2-7.8 | pH controls chlorine effectiveness and swimmer comfort. Only stable once TA is set correctly. Adjust after TA. |
| 3 | Calcium Hardness (CH) | 200-400 ppm | Rarely needs frequent adjustment. Low CH is corrosive; high CH causes scaling. Adjust after pH is stable. |
| 4 | CYA (Stabilizer) | 30-50 ppm | Adjust only if testing confirms outside range. CYA accumulates from trichlor tablets — more commonly too high than too low. |
| 5 | Free Chlorine | 1.0-4.0 ppm | Adjust last. Shock or add tablets after all other parameters are balanced. Shocking at wrong pH wastes product. |
Step 1: Adjusting Total Alkalinity
How to raise total alkalinity
Product: sodium bicarbonate (baking soda). Pool store versions labeled ‘alkalinity increaser’ are the same chemistry at 3-5x the price.
Raising Total Alkalinity
Standard dose: 1.5 lbs sodium bicarbonate per 10,000 gallons raises TA ~10 ppm
Example: 20,000-gallon pool, current TA 60 ppm, target 100 ppm
Increase needed: 40 ppm
Calculation: (40 / 10) x (20,000 / 10,000) x 1.5 = 12 lbs
Add in two doses of 6 lbs each, 4 hours apart.
Retest before the second dose.
✓ KEY FACT: Sodium bicarbonate also raises pH slightly. When raising TA by large amounts (30+ ppm), retest pH after TA is set before making pH adjustments.
How to lower total alkalinity
Product: muriatic acid (liquid) or sodium bisulfate (dry acid). Both lower pH and TA together. The technique for lowering TA specifically without proportionally crashing pH is to add acid in a concentrated area, let it work, then aerate to bring pH back up without raising TA.
The acid-aeration method: add muriatic acid or sodium bisulfate to lower both pH and TA, then run water features, fountains, or point return jets upward to aerate the water. Aeration raises pH through CO2 off-gassing without raising TA. Repeat until TA is in the 80-120 ppm range. This takes patience — a pool with TA at 180 ppm may need 2-3 treatment cycles over several days.
Step 2: Adjusting pH
How to raise pH
Product: soda ash (sodium carbonate). Sold as ‘pH increaser’ or ‘pH Up’ at pool stores.
Raising pH with Soda Ash
Standard dose: 6 oz (170g) soda ash per 10,000 gallons raises pH ~0.2 units
Example: 15,000-gallon pool, current pH 7.0, target 7.4
Increase needed: 0.4 units
Calculation: (0.4 / 0.2) x (15,000 / 10,000) x 6 oz = 18 oz
Pre-dissolve in a bucket of pool water before adding.
Add slowly near a return jet. Retest after 4-6 hours.
How to lower pH
Product: sodium bisulfate (dry acid / pH Down) or muriatic acid (liquid). Sodium bisulfate is safer to handle and store; muriatic acid works faster and is less expensive per dose.
Lowering pH with Sodium Bisulfate
Standard dose: ~1 lb per 10,000 gallons drops pH ~0.2-0.4 units
(actual drop varies with starting pH and total alkalinity)
Example: 20,000-gallon pool, current pH 7.8, target 7.4
Decrease needed: 0.4 units
Estimated dose: 2-4 lbs (test after 4 hours and adjust)
Broadcast over the deep end with pump running.
Never add to skimmer. Never add more than 2 lbs at a time.
Retest after 4-6 hours before adding more.
⚠ WARNING: Always add acid to pool water — never add water to acid. Broadcast sodium bisulfate granules over the water surface near return jets. For muriatic acid, dilute it in a bucket of pool water first and pour it slowly around the pool perimeter. Never add either product through the skimmer.
Step 3: Adjusting Calcium Hardness
How to raise calcium hardness
Product: calcium chloride (sold as ‘calcium hardness increaser’ or pool-grade calcium chloride).
Raising Calcium Hardness
Standard dose: 1.25 lbs calcium chloride per 10,000 gallons raises hardness ~10 ppm
Example: 20,000-gallon pool, current CH 150 ppm, target 250 ppm
Increase needed: 100 ppm
Calculation: (100 / 10) x (20,000 / 10,000) x 1.25 = 25 lbs
Pre-dissolve in a bucket of pool water. Add slowly.
Calcium chloride generates significant heat when dissolving —
handle with gloves and eye protection.
Wait 4 hours and retest before adding more.
⚠ WARNING: Calcium chloride generates substantial heat when it dissolves in water. Always add the chemical to a bucket of water — never add water to dry calcium chloride. Pre-dissolving prevents localized high-concentration zones on pool surfaces that can bleach vinyl liners or etch plaster.
How to lower calcium hardness
There is no chemical that removes calcium from pool water. The only methods are: (1) partial drain and refill with softer water, or (2) reverse osmosis treatment by a pool service company. For most residential pools, a partial drain of 1/4 to 1/3 of the pool volume and refill with fill water is the practical approach. Before draining, test your fill water’s calcium hardness — some municipal water supplies run 200-300 ppm calcium, which means dilution is less effective than expected.
The Relationship Between These Three Parameters
pH, total alkalinity, and calcium hardness interact through the Langelier Saturation Index (LSI) — a calculation that determines whether water is balanced, scale-forming, or corrosive. The LSI considers all three parameters together with water temperature and TDS (total dissolved solids).
Balanced water (LSI near zero) neither etches surfaces nor deposits scale. Negative LSI: water is corrosive — it pulls calcium from plaster, grout, and equipment to satisfy its mineral demand. Positive LSI: water is scale-forming — it deposits calcium on surfaces and equipment.
This is why fixing one parameter in isolation can cause problems elsewhere. A pool with low TA and low CH at pH 7.4 may look chemically fine on a simple test but run a negative LSI that slowly etches the plaster. The three parameters must be considered together.
Quick Reference: Common Imbalance Symptoms
| Symptom | Most Likely Cause | First Test | Fix |
| pH keeps rising despite adding acid | TA too high (above 120 ppm) — buffering pH upward | Test TA | Lower TA using acid-aeration method. TA in correct range makes pH stable. |
| pH keeps dropping despite adding soda ash | TA too low (below 80 ppm) — no buffer to hold pH up. Also: trichlor tablets continuously lowering pH. | Test TA | Raise TA with sodium bicarbonate first. Then re-adjust pH. |
| Cloudy water despite correct chlorine | High calcium hardness above 400 ppm causing calcium carbonate precipitation | Test CH | Maintain pH at 7.2-7.4 (lower pH keeps calcium dissolved). Long-term: partial drain. |
| Pool surfaces etching or pitting (plaster/concrete) | Low calcium hardness below 200 ppm or negative LSI — water pulling calcium from surfaces | Test CH and calculate LSI | Raise CH with calcium chloride. May need to adjust TA and pH together to improve LSI. |
| Scale deposits on equipment or waterline | High calcium hardness above 400 ppm and/or high pH creating positive LSI | Test CH and pH | Lower pH to 7.2-7.4. Long-term: partial drain to reduce CH. |
| Chlorine not holding despite correct FC reading | CYA too high (above 80 ppm) — chlorine bound to CYA and inactive | Test CYA | Partial drain and refill. Target CYA 30-50 ppm per PHTA APSP-11. |
Source: PHTA Water Balance Fact Sheet 2022 — pH, TA, CH targets; LSI calculation factors
If X Happens, Do Y
I adjusted pH correctly but it drifted back out of range within 2 days
Total alkalinity is out of range. Test TA. If above 120 ppm, the high TA is buffering pH upward faster than your adjustments can hold. If below 80 ppm, pH is unstable because there is no buffer to hold it. Fix TA first, then re-adjust pH. pH stability is a symptom of TA being correct — not something you can directly solve by adding more pH chemicals.
My pool water is always cloudy no matter what I do to the chemistry
If pH, TA, and FC are all in range and the water is still persistently cloudy, test calcium hardness. CH above 400 ppm is the most commonly missed cause of persistent cloudiness. The water appears white or milky even after treatment because calcium carbonate is continuously precipitating out of solution. Lower the pH to 7.2-7.4 as a temporary measure (lower pH keeps calcium in solution) and plan a partial drain to reduce CH.
My new pool is etching — the plaster is rough and is getting pitted
Negative LSI — the water is corrosive. This happens when calcium hardness is low (below 200 ppm) or TA is low (below 80 ppm) or both. These conditions make the water chemically hungry for calcium, and it pulls calcium from the plaster to satisfy the demand. Test CH and TA immediately. Raise CH to 250-300 ppm with calcium chloride and raise TA to 80-100 ppm with sodium bicarbonate before more etching occurs. New pools with fresh plaster are particularly vulnerable in the first 30-60 days.
Related Guides
→ Pool Chemical Buying Guide: Everything You Need, Nothing You Don’t