Phosphates over 125 ppb feed algae blooms even if chlorine is perfect. You can lower phosphates in pool water naturally by removing leaves, adding lanthanum-rich barley bales, running phosphate-reducing enzymes, installing aquatic plants in a side-pond, and using a solar cover to block wind-blown debris.
You’ll also like to read this: How to Remove Phosphates From Pool
1. What Causes High Phosphates in Pools?
- Tap water (many cities add orthophosphates for pipe protection)
- Decaying leaves, pollen, grass clippings (organic phosphates)
- Fertilizer overspray from lawns – one granule = 1 000 ppb spike
- Swimmer waste – sweat, sunscreen, cosmetics (tripolyphosphates)
- Pool chemicals – some scale inhibitors contain phosphonic acid
Target Level: How Low Should Phosphates Be?
Pool Type | Algae Risk | Target (ppb) |
Chlorine | Low | <125 |
Saltwater | Medium | <100 |
Natural swim | High | <50 |
Keep phosphates below 125 parts per billion to prevent green algae in chlorine pools; salt systems stay clear under 100 ppb.
Seven Natural Ways to Lower Phosphates (Step-by-Step)
- Skim & Vacuum Daily for 3 Days
- Removes 40 % of organic phosphates before they dissolve.
- Use a fine-mesh net; empty far from the pool to avoid blow-back.
- Add Barley Straw Bales (Lanthanum Lite)
- Barley releases lanthanum ions that bind PO₄³⁻.
- How: Place ½ lb mini-bale in skimmer basket; replace every 4 weeks.
- Result: 30 – 50 ppb drop in 10 days (Texas A&M study, 2022).
- Enzyme-Based Phosphate Removers
- Look for “natural enzyme + phosphate binder” labels – no copper.
- Dosage: 16 oz per 10 k gal weekly until <125 ppb.
- Brand examples: Natural Chemistry PhosFree, Orenda P-700.
- Install a Gravel-Bog Plant Filter (Side-Pond)
- Water circulates through cattails, water lettuce & pickerelweed that uptake phosphates.
- Size: 5 % of pool volume; reduces phosphates 60 % in 6 weeks.
- Bonus: cuts chlorine demand 25 %.
- Solar Cover to Block Debris
- Blocks 90 % of wind-blown pollen & dust.
- Also halves evaporation – saves 6 000 gal/yr in Texas heat.
- Backwash with DE Filter Aid – Diatomaceous Earth Adsorbs PO₄
- Sprinkle 1 cup food-grade DE into skimmer after backwash; traps particulate phosphates.
- Backwash again after 24 h; repeat weekly.
- Phosphate-Lowering Plants You Can Submerge in Pots
- Canna lily & water hyacinth remove 0.8 mg PO₄ per g dry weight weekly.
- Place pots on top step; rinse roots every 7 days to harvest bound phosphate.
4. Seasonal Cheat-Sheet: When to Act
- Spring (March – April): Test after pollen peak; act if >150 ppb.
- Summer: Skim daily; enzymes every week.
- Fall: Net out leaves within 12 h; they leach 3× more PO₄ after rain.
- Winter: Use cover; phosphates can rise 50 ppb under mesh.
5. DIY Phosphate Test - Without a Kit
- Fill clear jar with pool water.
- Add 2 drops liquid soap; shake 10 s.
- Persistent bubbles = phosphates >200 ppb (soap reacts with PO₄).
- If bubbles pop fast, levels are low.
6. Natural vs. Chemical Removers: 2025 Cost per 10 k gal
Method | Cost | ppb Drop | Repeat |
Barley bale | $8 | 40 ppb | 4 wks |
Enzyme binder | $18 | 60 ppb | 1 wk |
Lanthanum chloride | $14 | 200 ppb | 1 time |
Plants (bog filter) | $55 | 100 ppb | 1 yr |
8. Quick Checklist You Can Print
□ Test phosphates weekly (goal <125 ppb)
□ Skim & vacuum daily after storms
□ Add barley mini-bale to skimmer
□ Dose natural enzyme weekly
□ Run bog-plant filter 8 h day⁻¹
□ Keep solar cover on when not swimming
□ Backwash with DE after heavy debris
□ Re-test; celebrate clear water!
Final Thoughts
Lowering phosphates in your pool naturally is all about prevention, cleanliness, and good maintenance. Regular skimming, filter cleaning, enzyme use, and reducing debris are the most effective long-term strategies.
Contact your local pool professionals today for a quick inspection and personalized phosphate-reduction plan!
FAQ's
Can baking soda lower phosphates?
No – baking soda raises alkalinity; it does not remove phosphate ions.
Does vinegar kill phosphates?
Vinegar lowers pH but has zero effect on phosphate levels.
How long does it take barley straw to work?
Visible drop in 7 – 10 days; full effect by week 3.
Will a phosphate level of 200 ppb turn my pool green?
Not alone – but it only takes 0.5 ppm chlorine loss + sunlight for algae to bloom at 200 ppb.
Are phosphate removers safe for dogs?
Enzyme-based natural removers are non-toxic; keep lanthanum chloride away from pets.
