Hayward Pool Sand Filter Problems & Fixes

by

If your Hayward sand filter isn’t keeping your pool clean, you’re not alone. Whether the water’s cloudy, pressure is off, or sand is blowing into the pool, these are common signs that your sand filter isn’t working right. This guide explains every major Hayward pool sand filter problem and gives you the practical fixes you need to get your pool back to sparkling clear.

Why Hayward Sand Filters Are Popular—and What Can Go Wrong

Hayward sand filters like the S244T and S310T are workhorses in backyard pools across the country. They’re reliable, simple to operate, and relatively low-maintenance. But like any mechanical system, problems crop up—usually when the filter isn’t maintained properly, the sand ages out, or internal parts wear down.

Below, you’ll find a complete breakdown of the most common issues, what causes them, and step-by-step ways to resolve them fast.

Table of Contents

Cloudy Water Despite Filter Running

Answer: If your water stays cloudy even when your Hayward sand filter is running for hours, your filter media may be exhausted or water is bypassing the sand bed.

  • Sand condition: Sand becomes smooth and rounded after 3–5 years. Old sand won’t trap fine particles.
  • Channeling: Water can create tunnels through the sand, avoiding filtration. This often happens when sand is packed too tightly or hasn’t been backwashed properly.
  • Improper filtration time: You may need to run your pump longer—especially after storms, parties, or algae blooms.

Fix: Replace sand if older than 4 years, break up clumps with a stick or broom handle, and check for channeling by inspecting during a drain.

Low Filter Pressure and Weak Return Flow

Answer: Low pressure often means there’s a restriction or air leak before the filter—affecting suction and circulation.

  • Skimmer or pump basket clogged: Clean both out weekly.
  • Pump lid O-ring: Replace or lubricate with silicone grease.
  • Air leaks in suction line: Listen for hissing sounds and inspect joints.
  • Valves partly closed: Fully open suction and return valves.

Test tip: Fill the pump pot with water, prime the pump, and monitor whether the pressure rises and flow returns.

High Filter Pressure

Answer: A sand filter with unusually high PSI (10–15 PSI above baseline) usually has clogged sand or return restrictions.

  • Backwashing overdue: Backwash your filter whenever PSI rises 7–10 above your clean baseline.
  • Dirty sand bed: Add a sand filter cleaner once a month or after heavy use.
  • Return side blockage: Check return lines, eyeballs, or heaters for clogs.

Note: If backwashing doesn’t resolve high pressure, it may be time to change the sand completely.

Sand Blowing Into Pool

Answer: Finding sand in the bottom of your pool is a strong sign that a lateral is broken or the standpipe is misaligned.

  • Broken lateral fingers: These plastic arms at the base of the tank keep sand inside—if cracked, sand escapes.
  • Incorrect sand type: Use only #20 silica sand—not play sand or filter balls unless specifically approved.
  • Overfilling: Fill tank to only 2/3 of the way with sand—excess creates pressure that forces sand out.

Fix: Drain the tank, remove old sand, inspect and replace all laterals. Never try to patch them—it’s not reliable.

Backwash and Rinse Not Working Properly

Answer: If your filter doesn’t backwash effectively or rinses improperly, the valve may be clogged, or sand is compacted.

Try the following:

  • Multiport valve check: Make sure handle rotates fully and spring is intact.
  • Sand channeling: Rinse and agitate sand during backwash—break up crusted areas manually.
  • Dirty sight glass: Watch until backwash water runs clear before switching to rinse.

Tip: Always follow the full backwash > rinse > filter sequence to prevent debris return to the pool.

Multiport Valve Leaking or Malfunctioning

Answer: A leaking or malfunctioning valve will cause water to leak out the waste line, return dirty water, or prevent sealing between modes.

  • Spider gasket worn: This internal seal wears down—inspect and replace every 2–3 years.
  • Handle spring broken: Causes misalignment inside valve body.
  • Cracked housing: Exposed to winter freezing or sun damage, the valve body may fracture.

Fix: Replace the spider gasket and handle spring or install a new valve top assembly if needed.

Filter Not Cleaning Pool Effectively

Answer: Poor cleaning performance is usually a sign of aged sand, poor circulation, or incorrect water chemistry.

  • Sand age: Sand filters best in its first 3 years. Replace when dirty or compacted.
  • Pump too small: Undersized pumps may not push enough water for the filter to clean efficiently.
  • Algae: Dead algae particles are too small for worn-out sand to catch—use clarifiers or flocculants as a boost.

Recommendation: Deep clean your filter media and verify your pump-to-filter sizing for optimal results.

Broken Laterals or Internal Parts

Answer: Damaged internal parts inside the Hayward sand filter will lead to sand loss, low flow, or bypassed filtration.

  • Laterals: Check all 8–10 lateral arms for cracks when replacing sand.
  • Standpipe: This vertical pipe must be seated correctly and remain undamaged.
  • Diffuser (top spreader): If broken, water won’t disperse evenly over sand, reducing efficiency.

Fix: Always inspect and replace broken internals when changing filter sand to avoid repeating the process.

When to Change Your Filter Sand

Answer: Pool filter sand should be replaced every 3–5 years, depending on usage and water quality.

Signs it’s time to replace:

  • Persistent cloudiness despite clean chemistry
  • High pressure even after backwashing
  • Sand clumps or channels observed during inspection

Process: Drain water, scoop or vacuum out sand, rinse tank, inspect internals, and refill with #20 silica sand per specs (usually 200–300 lbs).

Conclusion & Next Steps

Hayward pool sand filters are reliable, but like all filtration systems, they need attention to keep working right. Whether it’s clogged sand, leaky valves, or worn internal parts, diagnosing the issue early will save you time, money, and a whole lot of frustration.

Stick to a maintenance schedule, replace parts when needed, and change your sand every few years. Your pool will reward you with consistently clean and safe water.

Need help choosing sand or troubleshooting your exact filter model? Drop a question below or subscribe for pro pool care tips and repair guides tailored to Hayward filter owners.


Leave a Comment