When Should I Add Backwash After Shocking Pool?

water mold in pool

When it comes to shocking your pool, you have numerous steps to follow. One of these steps includes cleaning your pool filter using a method that reverses the flow of water through your pool system–this process is called backwashing. When you maintain a clean and functioning pool filter, your pool is safe and clean to swim in.

Backwashing uses existing pool water to flush debris out of your filter media. This debris can be sand or diatomaceous earth (often referred to as DE). Once that is flushed out of your media, the debris exits through your filter’s backwash valve drain port.

When it comes to incorporating backwash into your shocking routine, we recommend you backwash before you shock your pool. Once the backwashing process begins, it is common to lose water. If you backwash after you have added your shock, you are losing chlorine and clean water. You want to flush out large debris and clear your filter before you add shock.

If you have already shocked your pool, don’t sweat it. You can still backwash your pool after shocking it. We recommend you wait at least forty-eight hours before backwashing, as the chemicals from the shock can increase pressure on your pool’s filter. To avoid damaging the filter, wait until the shock has dispersed through your pool.

The Ins and Outs of Backwashing

There is a lot of information on backwashing, but a lot of the information online is conflicting. There is debate around when you should add chlorine tablets after shocking your pool, and what shock is the best shock to use. We recommend referring to pool experts such as the Pool Care Guy for no-nonsense, honest tips and tricks to maintaining your pool.

How Often Should I Backwash?

How often you backwash your pool’s filter is contingent on multiple factors. Is your pool used frequently, by a large number of swimmers? Is your pool surrounded by trees or other foliage? You may need to backwash more frequently.

Generally, you should backwash your pool about once a week. You can align this to your scheduled maintenance. If this doesn’t feel like enough, you can check your filter’s pressure gauge. If the gauge reads eight to ten PSI (pounds per square inch) over the starting level, it’s time to backwash. 

Pay attention to conditions in your area. If a major storm has occurred or there is an algae outbreak in your area, it’s time to backwash.

When You Shouldn’t Backwash

There are several circumstances where you should avoid backwashing. Many pool owners wonder if they can add shock to their pools after adding baking soda, and how backwashing works into that routine. You definitely can, but you need to wait at least six hours for the baking soda to dissolve.

Another example is if your pool uses a cartridge filter. It is more effective to remove the cartridges and clear them with a hose. If you have an algae issue, consider that most algae bypasses your filter and re-enters the pool. It is better to vacuum this waste directly; this also applies if your pool has been exposed to a large volume of dirt or debris.

Backwashing is an important step in pool maintenance–it is an extensive process that can easily be incorporated into your weekly pool cleaning routine. Before beginning the backwash process, always wait for all added chemicals to dissolve. Once that’s done, you’ll have a beautiful pool and happy swimmers.

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