Adjusting pH

It is recommended that dry chemicals first be mixed into a generous amount of water in increments of about two pounds (1 kg), and the predissolved mixture be distributed evenly around the pool unless directed otherwise.

Precautions

  • Never add water to chemicals; always add chemicals to water.
  • Always follow manufacturer’s recommendations and warnings on product labeling.
  • Never mix two chemicals together since their pH might vary and could cause an explosion or fire.

A pH range of 7.2 – 7.8 is ideal for pools and spas. Since 7.5 is the midpoint of this range, we have provided the tables below to help in adjusting up or down to this pH. After testing the pH, find the pH in the left hand column and match this with the volume of water in your pool or spa, listed at the top of the table. Since the recommendations are approximate, you may wish to initially add slightly less and wait 4-8 hours to retest the water. Keep in mind that pH adjustments will affect alkalinity.

 

Lowering pH to 7.5 with Muriatic AcidNotes:Treatment recommendations are affected by total alkalinity. At low alkalinity levels less acid may be required and at higher alkalinity levels more acid may be required.

U.S. Customary Units:

Starting from 100 Gallons 1,000 Gallons 5,000 Gallons 10,000 Gallons 20,000 Gallons 50,000 Gallons
pH — Tsp Pt Oz Pt Oz Pt Oz Pt Oz Pt Oz
7.6 – 7.8 — 0.75 0 1.3 0 6.4 0 12.8 1 9.6 4 0
7.8 – 8.0 — 1 0 1.9 0 9.6 1 3.2 2 6.4 6 0
8.0 – 8.4 — 1.5 0 2.6 0 12.8 1 9.6 3 3.2 8 0
>8.4 — 2 0 3.2 1 0 2 0 4 0 10 0

Metric Units:

Starting from 400 Liters 4000 Liters 20000 Liters 40000 Liters 80000 Liters 200000 Liters
pH liters mL liters mL liters mL liters mL liters mL liters mL
7.6 – 7.8 — 4 0 41 0 200 0 400 0 800 2 0
7.8 – 8.0 — 6 0 59 0 300 0 600 1 200 3 0
8.0 – 8.4 — 8 0 81 0 400 0 800 1 600 4 0
>8.4 — 10 0 100 0 500 1 0 2 0 5 0

 

Lowering pH to 7.5 with Dry Acid (Sodium Bisulfate)

U.S. Customary Units:

Starting from 100 Gallons 1,000 Gallons 5,000 Gallons 10,000 Gallons 20,000 Gallons 50,000 Gallons
pH — Tsp Lb Oz Lb Oz Lb Oz Lb Oz Lb Oz
7.6 – 7.8 — 1 0 1.6 0 8 0 16 1 12 5 0
7.8 – 8.0 — 1.5 0 2.4 0 12 1 4 3 8 8 0
8.0 – 8.4 — 2 0 3.2 0 16 1 12 4 4 10 0
>8.4 — 2.5 0 4 1 0 3 0 5 0 13 0

Metric Units:

Starting from 400 Liters 4000 Liters 20000 Liters 40000 Liters 80000 Liters 200000 Liters
pH Kg g Kg g Kg g Kg g Kg g Kg g
7.6 – 7.8 0 5 0 48 0 240 0 480 0 840 2 400
7.8 – 8.0 0 7 0 72 0 360 0 600 1 980 3 840
8.0 – 8.4 0 10 0 96 0 480 0 840 2 40 4 800
>8.4 0 10 0 120 0 480 1 440 2 400 6 240

 

Notes:Treatment recommendations are affected by total alkalinity. At low alkalinity levels less acid may be required and at higher alkalinity levels more acid may be required.

 

Raising pH to 7.5 with Soda Ash

U.S. Customary Units:

Starting from 100 Gallons 1,000 Gallons 5,000 Gallons 10,000 Gallons 20,000 Gallons 50,000 Gallons
pH — Tsp Lb Oz Lb Oz Lb Oz Lb Oz Lb Oz
7.2 – 7.4 — 0.4 0 0.6 0 3.2 0 6.4 0 12.8 2 0
7.0 – 7.2 — 0.6 0 1 0 4.8 0 9.6 1 3.2 3 0
6.8 – 7.0 — 0.8 0 1.3 0 6.4 0 12.8 1 9.6 4 0
<6.7 — 1 0 1.6 0 8 1 0 2 0 5 0

Metric Units:

Starting from 400 Liters 4000 Liters 20000 Liters 40000 Liters 80000 Liters 200000 Liters
pH Kg g Kg g Kg g Kg g Kg g Kg g
7.2 – 7.4 0 2 0 18 0 96 0 192 0 384 0 960
7.0 – 7.2 0 3 0 30 0 144 0 288 0 576 1 440
6.8 – 7.0 0 4 0 39 0 192 0 384 0 768 1 920
<6.7 0 5 0 48 0 240 0 480 0 960 2 400

 

Notes:Treatments in low alkalinity waters require less soda ash while treatments in high alkalinity waters may require more soda ash.