How to Backwash a Sand Filter

There are three pool filter types that you can choose to keep your pool clean. However, among them, sand filters are the easiest and most cost-efficient to maintain and clean. When you can see that the filter’s efficiency has dropped, it is probably time to clean it.

Through this article, you will learn why, when, and how to backwash a sand filter.

Why Do You Need to Backwash a Sand Filter

Every pool equipment requires cleaning and maintenance. Backwashing is a maintenance procedure that must be conducted on a sand filter to ensure optimum efficiency. To understand why a sand filter needs backwashing, you will have to learn how the filter works.

A sand filter is full of #20-grade sand. This sand is capable of capturing particles from your pool that range from 20 to 100 microns. This filter’s job is to trap as many particles as it can from your pool to provide you with clean water. However, this sand requires to be cleaned from time to time.

There are two simple ways of knowing if your sand filter requires backwashing. You can be assured of backwashing requirements when the efficiency of the filter falls or when the filter is 8-10lbs heavier. If you fail to backwash your sand filter, the efficiency of the filter will drop. It will also reduce your filter’s durability, increasing the overall cost of your pool’s maintenance.

When to Backwash a Sand Filter

There is debate among experts about how frequently a sand filter should be backwashed. Some filters suggest that backwashing a sand filter once a week is the right way to go about maintenance. However, other experts say that you must only backwash a filter when it is dirty.

So, how do you know that the filter is dirty? You could check the pool water’s TDS level, visual clarity, flow rate, and PSI level. If any of these levels seem out of ordinarily low or dirty, you would know that it is time to backwash your sand filter.

There is no harm in following the one-week method. However, you might have to backwash the filter sooner in case of heavy rainfall or chemical treatments. Regular backwashing is the key to maintaining the efficiency of your sand filter.

How to Backwash a Sand Filter

Now that you know the why and the when of the backwashing process, you need to know a few things about how to backwash a sand filter. As mentioned above, sand filter maintenance is the most cost-effective one. The reason for this is straightforward.

When you use a cartridge filter, you will have to clean the system with some external tools manually. However, when you are washing a sand filter, all you need to do is invert the function. This means that the filter will use the water from your pool and rinse out the debris from the filter sand. This debris then drains away with the rest of the drainage water from the attached hose.

The basic principle involved in backwashing a sand filter is simple and universal. However, each type of filter might require different methods of backwashing. Given below is a detailed explanation of how to wash two types of sand filters.

Backwashing a Two-Way Valve Filter

You must follow the given steps to backwash a two-way valve sand filter.

1. Turn off the motor of the filter. This is when you’d want to roll out the backwashing hose if there’s one.
2. Twist the T-handle to unlock the plunger. Carefully pull it up by 3 or 4 inches.
3. Locate the filter’s air bleeder assembly and open it. You can turn on the filter now.
4. Watch for kinks in the hose and keep an eye on the pressure gauge. In case of the pressure spikes, you must turn off the pump immediately. Therefore, be prepared to execute the quick action.
5. Let the pump run for about 4 minutes when the hose is full. However, you could also wait for the wastewater to be completely clear to know that the filter is clean.
6. Turn off the filter again. Twist and reset the T-handle t its original position.
7. You can turn on the filter now. Do not forget to note the lowered pressure. You will require this pressure to see when the next time for backwashing is.
8. Take a marker and mark the old and new pressure points on the filter tank. This is a vital step to ensure that you have a reference point for the next time you need to backwash the sand filter.

Backwashing a Multifold Valve Filter

You must follow the given steps to backwash a multifold valve sand filter.

1. Turn off the motor of the pump.
2. Turn the valve handle from Filter to Backwash.
3. Open the waste line and the backwash hose, if any.
4. Locate the filter’s air bleeder assembly and open it. You can turn on the filter now.
5. Watch for kinks in the hose and keep an eye on the pressure gauge. In case of the pressure spikes, you must turn off the pump immediately. Therefore, be prepared to execute the quick action.
6. Let the pump run for about 4 minutes when the hose is full. However, you could also wait for the wastewater to be completely clear to know that the filter is clean.
7. Turn off the pump and push down the valve handle to Rinse.
8. Then turn on the pump and let it rinse out for about 30 seconds.
9. Turn off the filter again and shift the valve handle to Filter also.
10. Thenurn on the pump and mark the old and new pressure levels for reference.

Endnotes

Backwashing a sand filter is easy as long as you know when and how to do it. Once you have successfully backwashed your sand filter, your pool should be crystal clear within 24 hours. In case you still note some dirt in the pool, you might want to get the sand filter checked.