Pool Chemical Dosing Guide: How Much to Add by Pool Size
Adding pool chemicals without knowing the right amount is how pools end up cloudy, green, or damaging equipment. The correct dose depends on two things: your pool's volume and how far off your current reading is from the target. Get either one wrong and you're wasting chemicals, wasting money, or making the problem worse.
This guide gives you the exact dosing amounts for every common pool chemical, organized by pool size, so you can add with confidence.
Step 1: Know Your Pool Volume
Every dosing calculation starts with knowing how many gallons of water your pool holds. If you don't know your pool volume, here's how to calculate it.
Pool volume formulas
Rectangular pools: Length (ft) x Width (ft) x Average Depth (ft) x 7.5 = Gallons
Round pools: Diameter (ft) x Diameter (ft) x Average Depth (ft) x 5.9 = Gallons
Oval pools: Long Diameter (ft) x Short Diameter (ft) x Average Depth (ft) x 5.9 = Gallons
Kidney or freeform pools: Length (ft) x Width (ft) x Average Depth (ft) x 7.0 = Gallons (approximate)
Calculating average depth
Average Depth = (Shallow End Depth + Deep End Depth) / 2
For pools with a gradual slope, this works well. For pools with a steep dropoff to a deep end, you may want to calculate the shallow and deep sections separately and add them together.
Common pool sizes in DFW
Most residential pools in the Northlake and DFW North area fall into these ranges:
| Pool Type | Typical Dimensions | Approximate Volume |
|---|---|---|
| Small | 10 x 20, avg 4.5 ft | 6,750 gallons |
| Medium | 15 x 30, avg 5 ft | 16,875 gallons |
| Large | 18 x 36, avg 5.5 ft | 26,730 gallons |
| Extra large | 20 x 40, avg 6 ft | 36,000 gallons |
| Common freeform | ~15 x 30, avg 5 ft | 15,000-18,000 gallons |
For the dosing charts below, we provide amounts per 1,000 gallons. Multiply by your pool volume in thousands to get your dose.
Example: If the chart says "2 oz per 1,000 gallons" and your pool is 15,000 gallons, your dose is 2 x 15 = 30 oz.
Chlorine Dosing
Chlorine is your primary sanitizer. The target range is 2-4 ppm free chlorine for most pools. Always test before adding. See: Pool Water Testing for Beginners
Liquid chlorine (sodium hypochlorite, 10% or 12.5%)
Liquid chlorine is the cleanest form of chlorine — it doesn't add CYA or calcium.
| Desired Increase | 10% Liquid Chlorine per 1,000 gal | 12.5% Liquid Chlorine per 1,000 gal |
|---|---|---|
| +1 ppm | 1.3 fl oz | 1.0 fl oz |
| +2 ppm | 2.6 fl oz | 2.0 fl oz |
| +3 ppm | 3.8 fl oz | 3.0 fl oz |
| +5 ppm | 6.5 fl oz | 5.1 fl oz |
| +10 ppm | 13.0 fl oz | 10.2 fl oz |
Tips for liquid chlorine:
- Add in the evening to minimize UV loss
- Pour directly into the pool with the pump running, distributing around the perimeter
- Store in a cool, dark place — liquid chlorine degrades in heat and sunlight
- Fresh liquid chlorine is stronger; old product loses potency over weeks
For an in-depth comparison, see: Liquid Chlorine vs. Tablets: Which Is Better?
Granular chlorine (calcium hypochlorite / cal-hypo, 65-73%)
Cal-hypo is a strong, fast-dissolving granular chlorine. It adds calcium to the water.
| Desired Increase | Cal-Hypo (68%) per 1,000 gal |
|---|---|
| +1 ppm | 0.013 oz (about 1/3 tsp) |
| +2 ppm | 0.026 oz (about 2/3 tsp) |
| +5 ppm | 0.065 oz (about 1.5 tsp) |
| +10 ppm (shock) | 0.13 oz (about 1 Tbsp) |
Tips for cal-hypo:
- Never add directly to the skimmer — it can damage equipment
- Pre-dissolve in a bucket of water before adding to the pool
- Do not mix with other chemicals, especially trichlor or dichlor
- Adds approximately 0.8 ppm calcium hardness per 1 ppm chlorine increase
- Best used for shocking since it doesn't add CYA
Chlorine tablets (trichlor, 90%)
Tablets are used for ongoing, slow-release chlorination via floaters or inline/offline chlorinators.
| Pool Volume | Typical Weekly Tablet Usage (3" tablets) |
|---|---|
| 5,000-10,000 gal | 1-2 tablets |
| 10,000-15,000 gal | 2-3 tablets |
| 15,000-20,000 gal | 3-4 tablets |
| 20,000-30,000 gal | 4-5 tablets |
| 30,000-40,000 gal | 5-7 tablets |
Important warning about tablets:
- Each tablet adds approximately 0.6 ppm CYA per 1 ppm chlorine. Over months, this builds CYA to problematic levels.
- If your CYA exceeds 70-80 ppm, switch to liquid chlorine and stop using tablets until CYA drops.
- See: High CYA Levels and How to Fix Them
Shock Dosing
Shocking raises chlorine to high levels (10-30 ppm) to kill algae and oxidize contaminants. For the full shocking process, see: How to Shock a Pool: Complete Guide
Shock dosing by situation
| Situation | Target FC Level | Liquid Chlorine (12.5%) per 1,000 gal |
|---|---|---|
| Routine weekly shock | 10 ppm | 10.2 fl oz |
| Cloudy water | 15 ppm | 15.3 fl oz |
| Early algae (green tint) | 20 ppm | 20.4 fl oz |
| Full green pool | 30 ppm | 30.6 fl oz |
| Black/mustard algae | 30+ ppm | 30.6+ fl oz |
| After heavy use / pool party | 10-15 ppm | 10.2-15.3 fl oz |
Important: These targets assume CYA is at 30-50 ppm. Higher CYA requires proportionally higher chlorine levels to be effective. With CYA at 80 ppm, you may need 50% more chlorine to achieve the same kill rate.
Non-chlorine shock (potassium monopersulfate / MPS)
| Purpose | Dose per 1,000 gal |
|---|---|
| Weekly oxidation | 1 oz |
| Post-party cleanup | 1.5 oz |
| Cloudy water treatment | 2 oz |
Note: Non-chlorine shock oxidizes contaminants but does NOT kill algae. It is not a substitute for chlorine shock when algae is present.
pH Adjustment
Target pH: 7.2-7.6. Test before adjusting. DFW water naturally trends high (alkaline), so you'll typically need to lower pH more often than raise it.
Lowering pH (muriatic acid — 31.45% hydrochloric acid)
| Desired Decrease | Muriatic Acid (31.45%) per 1,000 gal |
|---|---|
| -0.2 pH (e.g., 7.6 to 7.4) | 1.6 fl oz |
| -0.4 pH (e.g., 7.8 to 7.4) | 3.2 fl oz |
| -0.6 pH (e.g., 8.0 to 7.4) | 4.8 fl oz |
| -0.8 pH (e.g., 8.2 to 7.4) | 6.3 fl oz |
Tips for adding muriatic acid:
- Always add acid to water, never water to acid
- Pour along the pool perimeter with the pump running
- Wait 30 minutes before retesting
- Add in smaller increments if unsure — you can always add more
- Wear gloves and eye protection
- See: How to Lower Pool Alkalinity
Raising pH (soda ash / sodium carbonate)
| Desired Increase | Soda Ash per 1,000 gal |
|---|---|
| +0.2 pH | 0.75 oz |
| +0.4 pH | 1.5 oz |
| +0.6 pH | 2.25 oz |
| +0.8 pH | 3.0 oz |
Tips for adding soda ash:
- Pre-dissolve in a bucket of water before adding
- Add slowly near a return jet with the pump running
- Wait 1 hour before retesting
- Note: Soda ash also raises alkalinity (~5 ppm per dose)
- Can cause temporary cloudiness — this is normal and clears within hours
Total Alkalinity Adjustment
Target: 80-120 ppm
Raising alkalinity (sodium bicarbonate / baking soda)
| Desired Increase | Baking Soda per 1,000 gal |
|---|---|
| +10 ppm | 1.4 oz (about 2.5 Tbsp) |
| +20 ppm | 2.8 oz |
| +30 ppm | 4.2 oz |
| +40 ppm | 5.6 oz |
| +50 ppm | 7.0 oz |
Tips:
- Pre-dissolve in a bucket and pour near a return jet
- Maximum addition: raise alkalinity no more than 10 ppm per day for best results (larger pools can handle 20 ppm)
- Wait 6 hours before retesting
- Baking soda has minimal effect on pH (slight increase)
Lowering alkalinity (muriatic acid)
Lowering alkalinity uses the same acid as pH adjustment, but the technique differs. For the complete process, see: How to Lower Pool Alkalinity
| Desired Decrease | Muriatic Acid (31.45%) per 1,000 gal |
|---|---|
| -10 ppm | 2.1 fl oz |
| -20 ppm | 4.2 fl oz |
| -30 ppm | 6.3 fl oz |
| -40 ppm | 8.4 fl oz |
| -50 ppm | 10.5 fl oz |
Important: Acid lowers both pH and alkalinity. When you specifically want to lower alkalinity without dropping pH too far, add acid in one spot (near the deep end) with the pump off for 10-15 minutes. This concentrates the acid effect on alkalinity. Then turn the pump on to circulate and aerate to bring pH back up.
Cyanuric Acid (CYA / Stabilizer)
Target: 30-50 ppm
Raising CYA (granular cyanuric acid / stabilizer)
| Desired Increase | Cyanuric Acid per 1,000 gal |
|---|---|
| +10 ppm | 1.3 oz |
| +20 ppm | 2.6 oz |
| +30 ppm | 3.9 oz |
| +40 ppm | 5.2 oz |
Tips:
- CYA dissolves slowly — place in a sock or pantyhose and hang in front of a return jet, or dissolve in warm water
- Takes 3-7 days to fully dissolve and register on tests
- Do not add more than 40 ppm of CYA in a single application
- Test a week after adding to confirm levels
Lowering CYA
There is no chemical that removes CYA from pool water. The only way to lower CYA is to drain and replace water. See: High CYA Levels and How to Fix Them
Calcium Hardness
Target: 200-400 ppm (DFW tap water often provides 200-300 ppm naturally)
Raising calcium hardness (calcium chloride)
| Desired Increase | Calcium Chloride (77%) per 1,000 gal |
|---|---|
| +10 ppm | 0.9 oz |
| +20 ppm | 1.8 oz |
| +30 ppm | 2.7 oz |
| +50 ppm | 4.5 oz |
| +100 ppm | 9.0 oz |
Tips:
- Pre-dissolve in a bucket of water — calcium chloride generates heat when dissolving, so add slowly to room-temperature water
- Never add more than 50 ppm in a single application
- Wait 24 hours between additions
- Most DFW pools don't need calcium added — our tap water is naturally hard
Lowering calcium hardness
Like CYA, there is no chemical to remove calcium from pool water. The options are:
- Partial drain and refill with lower-calcium water
- Sequestrant chemicals to keep calcium in solution and prevent scaling (temporary measure)
Algaecide Dosing
Algaecide is used as a preventative or supplemental treatment — not a replacement for proper chlorination.
Quaternary algaecide (quat — most common, general purpose)
| Purpose | Dose per 1,000 gal |
|---|---|
| Weekly maintenance | 0.5-1 oz |
| Initial dose (new fill or post-treatment) | 2-3 oz |
Polyquat 60 algaecide (non-foaming, higher quality)
| Purpose | Dose per 1,000 gal |
|---|---|
| Weekly maintenance | 0.5 oz |
| Initial dose | 1-2 oz |
| Algae treatment (supplement to chlorine) | 2-3 oz |
Copper-based algaecide (for stubborn algae)
| Purpose | Dose per 1,000 gal |
|---|---|
| Treatment dose | Per label (varies by concentration) |
Warning: Copper algaecide can stain pool surfaces if overdosed or if pH drops too low. Test copper levels if using regularly. Use with caution on plaster pools.
For complete algae treatment protocols, see: Pool Algae Types, Treatment, and Prevention
Chemical Addition Safety Rules
These rules apply every time you add any chemical to your pool.
The golden rules
- Test before you add. Never dose blindly. Always know your current levels before adding anything.
- Add one chemical at a time. Wait at least 30 minutes between different chemicals (some require longer — see below).
- Never mix chemicals together. This includes in buckets, near each other on the deck, or in the same skimmer. Chemical reactions can produce toxic gas, fires, or explosions.
- Add chemicals to water, not water to chemicals. When pre-dissolving, put water in the bucket first, then add the chemical slowly.
- Run the pump. Always add chemicals with the pump running to ensure even distribution.
- Pre-dissolve granular chemicals. Undissolved granules can bleach or stain pool surfaces.
Wait times between chemicals
| Chemical Added First | Minimum Wait Before Adding Next Chemical |
|---|---|
| Muriatic acid | 30 minutes |
| Soda ash | 1 hour |
| Baking soda | 30 minutes |
| Liquid chlorine | 15-30 minutes |
| Cal-hypo shock | 30 minutes (or until FC drops below 5 ppm for algaecide) |
| Algaecide | 15 minutes |
| Calcium chloride | 1 hour |
| CYA (stabilizer) | 30 minutes |
Order of chemical additions
When you need to adjust multiple things at once, follow this order:
- Alkalinity first — TA is the foundation that stabilizes pH
- pH second — Once alkalinity is stable, adjust pH
- Chlorine/shock third — Chlorine effectiveness depends on proper pH
- CYA fourth — After sanitizer is set, adjust stabilizer
- Calcium hardness fifth — Adjust last since it interacts with pH and TA
- Algaecide last — Most algaecides work best at proper pH with adequate chlorine
Chemical handling safety
- Muriatic acid: Wear gloves, eye protection, and work upwind. The fumes are harmful. Store upright, away from other chemicals.
- Cal-hypo: Highly oxidizing. Keep away from organic material, other chemicals, and moisture. Store in a cool, dry, well-ventilated area.
- Liquid chlorine: Wear old clothes (it bleaches on contact). Avoid splashing. Rinse spills immediately.
- All chemicals: Keep out of reach of children and pets. Store in original containers with labels intact.
For more on safe storage, see: Pool Chemical Storage Safety Guide
DFW Water Considerations
North Texas tap water has characteristics that affect your chemical dosing:
What DFW water brings to the pool
| Parameter | Typical DFW Tap Water Range | Impact on Your Pool |
|---|---|---|
| pH | 7.8-8.5 | Naturally high — you'll add acid regularly |
| Alkalinity | 140-220 ppm | Comes in high — may need to lower after filling |
| Calcium hardness | 200-300 ppm | Usually in range, but some well water areas are higher |
| CYA | 0 ppm | Must be added after a fresh fill |
| Chlorine | 1-3 ppm (city chloramine) | Minimal — you still need to add pool-grade chlorine |
Seasonal dosing adjustments for DFW
Summer (June-September):
- Chlorine demand doubles or triples due to heat and UV
- Test and dose 2-3 times per week minimum
- Shock weekly or after heavy rains (spring storms)
- pH drifts up faster — check twice per week
- Evaporation concentrates minerals — watch calcium and CYA levels
Winter (December-February):
- Chlorine lasts much longer — test weekly
- Reduce tablet usage or switch to liquid for better control
- Alkalinity and pH still need monitoring but change more slowly
- Don't stop treating entirely — algae can grow whenever water is above 50 degrees F
Spring and Fall:
- Pollen (spring) and leaves (fall) increase chlorine demand
- Clean baskets and filters more frequently to maintain flow
- Watch for algae blooms during warm spells following rain
Get Your Chemicals at Simplified Pools
We carry every chemical mentioned in this guide at our Northlake store, along with testing supplies and dosing tools to make pool care simple and accurate.
- Visit our pool supply store for chemicals, test kits, and dosing accessories: Simplified Pools Supply Store
- Shop online for convenient delivery: Simplified Pools Online Shop
- Bring us a water sample and we'll test it for free and tell you exactly what to add and how much: Contact Us
- Call us: (469) 455-1054
Not sure what your pool needs? Bring a water sample to our store. We'll test it on our professional equipment and give you a precise dosing prescription for your pool — no guessing required.
