If you’ve been fighting algae all season, burning through chlorine faster than usual, or your water just won’t seem to stay clear — phosphates might be the culprit. Here’s what 15 years of pool experience has taught us about this hidden problem.
What Are Phosphates?
Phosphates are naturally occurring compounds that find their way into your pool from a surprising number of sources:
- Leaves, grass clippings and plant debris breaking down in the water
- Lawn fertilizers blown or washed in (huge source in spring)
- Rainwater runoff carrying soil and organic matter
- Swimmer residue — sweat, sunscreen, body wash
- Some pool chemicals themselves — certain algaecides and clarifiers contain phosphates
- Municipal tap water — many cities add phosphates to protect pipes
On their own, phosphates don’t make your water green or cloudy. The problem is what they feed.
Why Phosphates Are a Problem
Phosphates are algae food. Algae needs three things to thrive: sunlight, warmth, and nutrients. Phosphates are the primary nutrient source. When phosphate levels climb above 200–500 ppb (parts per billion), you’ve essentially set the table for an algae bloom.
Here’s what high phosphates look like in practice:
- You’re adding chlorine but it disappears fast — algae is consuming it
- Water turns green or cloudy seemingly overnight
- You shock the pool, it clears up, then it comes back within days
- Algae keeps growing even with proper chlorine levels
- Your chemical costs are way higher than they should be
We see this constantly in the Tri-Cities — especially in spring when lawns are being fertilized and pools are first being opened. A pool that sat covered all winter can accumulate serious phosphate levels from debris and runoff alone.
How to Test for Phosphates
Standard test strips and basic test kits do not test for phosphates. You need either:
- A phosphate-specific test kit (liquid reagent drop test)
- Or bring a water sample in to AquaZen for a free professional water test — our WaterLink SpinTouch tests for phosphates along with 10+ other parameters in about 60 seconds
What the numbers mean:
- 0–200 ppb — Good. No action needed.
- 200–500 ppb — Elevated. Treat now before problems start.
- 500–1,000 ppb — High. Algae risk is significant. Treat immediately.
- 1,000+ ppb — Very high. You may already have algae issues. Full treatment needed.
How to Get Rid of Phosphates
The good news: removing phosphates is straightforward once you know you have them. Here’s the step-by-step process we recommend:
Step 1 — Test First
Know your starting number. Bring a water sample to AquaZen (free) or use a phosphate test kit at home. You need to know how high you’re starting so you know how much remover to use.
Step 2 — Balance Your Water First
Adjust pH (7.2–7.6), alkalinity (80–120 ppm) and chlorine (1–3 ppm) before adding phosphate remover. Phosphate removers work best in balanced water.
Step 3 — Apply Phosphate Remover
We carry Water’s Choice Natural Pool Care products, which include an excellent phosphate remover that’s enzyme-based and gentle on your water. Apply according to your phosphate level:
- Add the remover near the pool return jets with the pump running
- The product will cause the phosphates to precipitate out (clump together)
- You may see temporary cloudiness — this is normal and means it’s working
- Run your filter continuously for 24–48 hours
Step 4 — Clean Your Filter
This is the step people skip — and it matters. After the phosphate remover has done its job, backwash your sand filter or clean your cartridge filter. The phosphates have been captured in the filter media. If you don’t clean it out, they can leach back into the water.
Step 5 — Retest
Test again 48–72 hours after treatment. If still above 200 ppb, do a second treatment. Severely elevated pools (1,000+ ppb) often need 2–3 treatments to get fully under control.
How to Keep Phosphates Low Going Forward
Prevention is easier than treatment. Here’s how to keep phosphates from building up:
- Skim and vacuum regularly — don’t let leaves and debris sit in the pool
- Shower before swimming — reduces sunscreen and body product contamination
- Rinse off after mowing near the pool — fertilizer and grass clippings are major sources
- Use a phosphate remover monthly as a preventive dose — much easier than treating a high-level problem
- Test for phosphates every 4–6 weeks during swim season — add it to your regular water testing routine
- Bring water to AquaZen for a free professional test — our WaterLink SpinTouch catches phosphate problems before they become algae problems
Why We Recommend Water’s Choice
We carry Water’s Choice natural pool care products because they align with what we believe: you shouldn’t need to dump a chemistry set into your pool to keep it clean. Water’s Choice uses enzyme-based formulas that work with your pool’s ecosystem rather than fighting it. Their phosphate remover is effective, safe for all pool types, and helps reduce your overall chlorine demand over time.
Less chlorine. Cleaner water. Happier swimmers. That’s the goal.
Not Sure Where to Start? Come See Us.
If your pool isn’t cooperating this spring, bring a water sample in to AquaZen. Our free professional water test gives you a full picture — including phosphate levels — in about 60 seconds. We’ll tell you exactly what’s going on and what it takes to fix it. No guessing, no overselling — just straight answers from people who’ve been doing this for 15 years.
📍 AquaZen Pool, Spa & Sauna
3121 Leslie Rd Ste 103, Richland, WA
📞 (509) 502-8966
Mon–Fri: 9am–6pm | Sat: 10am–5pm | Sun: 12pm–4pm
