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Pool Filter Blowing Out Sand? Here’s Why (+ How to Fix)

Your pool filter should never blow sand back into the water. If there’s sand in the pool, it’s almost always a sign that something’s broken. Failure to repair the damaged filter component can worsen the problem and cost expensive repairs. Furthermore, you’ll lose several pounds of sand and limit your filter’s cleaning capabilities.

If your pool filter is blowing out sand, here’s why:

  • Broken laterals
  • Too much sand in the filter
  • Not enough water
  • Compacted filter sand
  • Cracked standpipe
  • Overpowered pool pump
  • Long-term inactivity
  • Damaged filter tank
  • Multiport valve problems
  • Fresh sand change

Throughout this article, I’ll explain all of the reasons your pool has filter sand in it. I’ll also provide multiple solutions to repair your filter and prevent this issue from returning.

Broken Laterals

Pool sand filters work by pushing debris through compacted sand. Every sand filter has laterals that push and pull the debris through the media. If the laterals are broken, the sand can get into the water supply. One broken lateral is enough to send several pounds of sand into your swimming pool.

How to Fix

Repair the broken laterals with these steps:

  1. Turn off the pool pump.
  2. Remove the lid’s retaining bracket and the top of the tank.
  3. Scoop all of the sand out of the filter.
  4. Twist off the broken laterals and replace them with new ones).
  5. Pour a little bit of water into the tank, dump all of the required sand into the tank, then top it off with water until the sand is covered.
  6. Seal the filter’s tank, then turn on the pump and test your work.

Too Much Sand in the Filter

If there’s too much sand in the filter, it’ll flood the standpipe and send the extra media into the pool. Using the wrong type of sand in a pool filter can also cause this problem. If the sand’s density is reduced because it’s the wrong kind of sand, it won’t filter the debris. Furthermore, it’ll overload the laterals and increase their chances of breaking.

How to Fix

If there’s too much sand in the filter, try these suggestions:

  1. Turn off the pump and open the filter.
  2. Scoop out the sand until the filter is about halfway full.
  3. Check the filter’s sand requirements to know how much sand it needs.
  4. Top the sand with water until it’s covered, seal the filter tank, then turn on the pump.

Unfortunately, the only true way to fix this issue is to remove all of the sand and use however much the manufacturer recommends.

Not Enough Water in the Filter

If there’s not enough water in the filter, the sand won’t be compact enough. The dry sand flows into the standpipe and through the plumbing. This common problem often occurs when installing a new sand filter, changing all of the sand, or backwashing your pool filter. Backwashing pushes a lot of the water out of the filter. If the pipes are clogged, there won’t be enough water in the sand.

How to Fix

To fix this common issue, keep these tips in mind:

  • Unclog all of the unions and plumbing before and after the filter.
  • Make sure the standpipe and laterals are tightened in the filter’s tank.
  • Fill the filter with water until it’s about six inches above the sand.
  • Seal the filter lid and turn on the pump (don’t forget to open the air relief valve to remove all of the air from the system).

Compacted Filter Media

Compacted filter media often refers to saturated sand or DE. It’s important to change the sand every couple of years to prevent it from clogging or compacting. When the sand compacts, it sends debris into the plumbing. Some of the debris clings to the sand and forces it into the swimming pool.

How to Fix

If you think the sand is compacted and it needs to be changed, follow this method:

  1. Turn off the pump and open the filter’s lid, then scoop all of the sand out of the filter.
  2. Add about six to twelve inches of water into the empty filter tank (replace any broken laterals if necessary).
  3. Pour the manufacturer’s recommended amount of #20 silica sand into the filter.
  4. Cover the sand with a few inches of water.
  5. Tighten the filter’s lid and turn on the pump after opening the air relief valve.

Palmetto Pool Filter Sand comes in a 50-pound bag. Check your filter’s label to know how many bags you’ll need. This filter sand is free of debris and contaminants, making it a top-notch filter media that lasts for several years before it needs to be changed.

Palmetto Pool Filter Sand

Cracked Standpipe

The standpipe sits in the center of the filter. It holds all of the previously mentioned laterals. If the standpipe is cracked, it’s exposed to all of the sand in the filter. Unfortunately, replacing a cracked standpipe can be one of the most expensive and strenuous repairs. The good news is that it’s quite uncommon since the pipes are extremely durable.

How to Fix

To replace a cracked standpipe, try this step-by-step process:

  1. Open the filter’s lid after turning off the power to the pool equipment.
  2. Remove all of the sand from the filter (you can use the same sand when you fill the filter if it’s in good condition).
  3. Twist off the old, cracked standpipe.
  4. Twist on the new standpipe after rinsing all of the sand out of the filter.
  5. Connect the laterals to the standpipe.
  6. Pour six to twelve inches of water into the filter, then dump as much sand as required into the tank.
  7. Top off the sand with a few inches of water, seal the filter, then turn on the power.

Overpowered Pool Pump

Having an oversized pump can damage the filter. Too much pressure cracks the standpipe, laterals, and other internal components. Make sure your pump and filter have similar GPM (gallons per minute) ratings. Never get a pump with a GPM that’s several hundred units higher than the filter’s GPM.

How to Fix

If you have an overpowered pool pump, the only thing you can do is replace the pump. I suggest getting a new variable-speed pump since they offer the best energy savings, lowest noise output, and optimal customizations. You can keep the pump low enough for any swimming pool filter and increase it if you get a new one.

Long-Term Filter Inactivity

Not using your pool’s pump and filter can cause numerous problems. For example, it can combine the sand and oils, making it difficult for the filter to remove any of the debris. The clumped oil and sand force their way through the laterals and standpipe, clogging the plumbing and pushing sand into the swimming pool.

How to Fix

Try these suggestions:

  • Remove all plumbing clogs.
  • Backwash the sand to remove excess debris.
  • Change the sand after two to three years.
  • Replace all broken components.
  • Always run the filter daily, even during the winter.

Cracked Filter Tank

It’s very rare for a filter tank to crack. They’re designed to withstand UV rays, chemicals, water, and everything in between. However, heavy items and accidents can crack the filter tank. When the tank cracks, sand, and debris will almost always get into the plumbing. The sand will flow into the pool right when you turn on the pump.

How to Fix

If the filter tank is cracked, I typically recommend getting a new filter. The tank is almost always close to the same price as a whole filter. Furthermore, it requires the same replacement steps. You’ll have to disconnect the plumbing and get rid of all of the internal parts to add a new tank. It’s worth getting a new one if you’ve had the old filter for more than five to ten years.

Incorrect Multiport Valve Orientation

When you install a multiport valve, it’s essential to know which way everything faces. There are often three or more directions on the valve. If any of them are misaligned, you’ll perform the incorrect task when you turn the valve’s lever. For example, you might accidentally turn the water in the opposite direction, reversing the pump’s pressure and pushing sand into the pool.

How to Fix

Consider these tips:

  • Look for the arrows on the multiport valve to know which way they connect.
  • Replace the seals if they leak.
  • Never turn the valve unless you intend to change the filter’s function.

Fresh Sand Change

It’s not uncommon for a few grains of sand to make their way into the pool after a fresh sand change. This often happens when you accidentally spill some of the sand into the standpipe. This problem typically goes away after running the pump for a few hours, but it’s important to handle it as quickly as possible.

How to Fix

Here’s what you can do:

  • Place a towel over the standpipe when adding sand to the filter to prevent sand from getting into the pipe.
  • Brush the sand on the bottom of the pool and turn on the pump.
  • Always rinse the sand filter with the multiport valve after backwashing the sand.

Author

  • Jonah Ryan

    Jonah has worked for several years in the swimming pool industry installing and repairing equipment, treating pools with chemicals, and fixing damaged liners. He also has plumbing and electrical experience with air conditioning, ceiling fans, boilers, and more. When he's not writing for Temperature Master, he's usually writing for his own websites, LawnCareLessons.com and DIYByHand.com.

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