Pool shock spikes your chlorine levels to remove and prevent algae. It’s often required as a weekly or bi-weekly treatment in addition to chlorine tablets or liquid chlorine.
However, you should also shock your pool when opening it after the winter season. Shocking it after it opens will remove bacteria and debris in the water. But how much shock do you need to do this effectively?
You need enough shock to open your pool to elevate the chlorine levels to 6ppm. The algae can’t survive in these conditions. Use a 50% to 95% calcium hypochlorite shock to spike the chlorine, then circulate the pump for eight hours. Follow the shock with a pool clarifier to remove the cloudiness.
In this article, I’ll show you how much shock your pool opening needs, whether or not you need to shock it during every opening, and what happens if you add too much shock.
I’ll also explain how long it takes for the water to clear up after using the shock treatment. Let’s get started!
How to Tell How Much Shock You Need to Open Your Swimming Pool
Knowing how much shock to add to the pool depends on the company and the calcium hypochlorite concentration.
For example, some brands sell shock bags that treat 5,000 gallons, while some bags go up to 7,500 gallons per bag. Always read the labels to know how much shock should be added for your pool’s gallon total.
Covering your pool will reduce the amount of chlorine lost through evaporation. Solar covers help the pool by holding the chlorine (among other benefits), letting the shock treatment last much longer.
You can also use a solar cover or winter cover to maintain your pool’s chlorine levels during the winter. This process reduces the amount of shock necessary to open the pool.
Remember, it’s more important to pay attention to your pool’s chlorine levels than to decide on a predictable amount of bags per opening.
If your pool looks clear and the chemicals are maintained during the winter, you might not have to shock the pool other than regular weekly treatments.
Pro-tip: When shocking the pool, check the FAC (free available chlorine), not the TAC (total available chlorine). The total chlorine includes the chloramines, which don’t help the water. The FAC and TAC should be as close as possible to maintain a healthy pool.
Should You Shock Your Pool When Opening It?
You should shock your pool when opening it to raise the chlorine to maintainable levels. Shocking the water will get rid of algae, even if you can’t see it.
These harsh treatments can cloud the water, so it’s important to circulate the water for several hours after opening the pool. You should also add an algaecide and pH adjusters.
Adding shock to the pool can help you maintain the chlorine with liquid or tablets. The shock should be added weekly or bi-weekly for the rest of the summer, depending on how quickly the chlorine evaporates.
The pool should always be around 3ppm to 4ppm or 5ppm to 6ppm if you’re fighting an algae bloom.
There are many other chemicals needed for swimming pools, though. You should add pH and alkalinity adjusters, calcium (if needed), cyanuric acid (also known as pool conditioner), and a few other treatments.
Here’s when you should shock a pool after opening it:
- If the chlorine is below 4ppm
- Whenever there’s algae in the water
- If the water looks cloudy, green, or otherwise discolored
- If you expect a lot of people or pets to be in the pool within a few days
Keep in mind that you can add too much shock and cause all sorts of issues. Read on to find out how to avoid this common concern.
Can You Over-Shock a Pool?
You can over-shock a pool by raising the chlorine levels over 7ppm. If your chlorine levels get too high, they can cause skin irritation, corrode the liner, and damage the pool equipment.
Keep the solar cover off of the pool and add water to dilute the chlorine if you think you’ve added too much.
Pro-tip: Following a routine shock schedule will prevent the pool from having too much chlorine.
Here’s what happens if you add too much shock to the pool:
- Chlorine can cause skin and eye irritation. Chlorine is very harsh, especially when it’s in its concentrated form. The chlorine should never exceed 6ppm when people are swimming in the pool.
- The water will look cloudy. Most shock treatments cause a little bit of cloudiness due to the fine powder particles. However, adding too much shock will make the water extremely cloudy and difficult to clear up.
- Too much shock can damage the pump, heater, filter, and other pool equipment. High chlorine levels will quickly corrode the plumbing. Never keep the chlorine above 7ppm for too long, even when you’re treating an algae bloom.
How Long After Shocking Your Pool Will It Clear Up?
Your pool will clear up within a few hours after shocking it. However, dead algae from the chlorine might take a couple of days to clear up.
You can accelerate the process by cleaning the filter and adding a water clarifier. These chemicals increase the filter’s micron density, helping them remove as much debris as possible.
I recommend adding a pool clarifier after shocking the pool, but you should wait at least eight hours to let the shock circulate through the water. In my experience, most shock treatments clear up within a few hours, so you shouldn’t have to worry about a clarifier.
Nevertheless, it’s essential to have one on hand in case you add too much shock or the shock kills enough algae.
Dead algae looks cloudy, much like an overload of shock. If you notice algae in the water before the shock treatment, you’ll likely have to use a clarifier to get rid of the cloudiness.
If you want to get rid of dead algae, I suggest using Robarb Super Blue Clarifier. It goes into the filter and collects as much debris as possible. Run the filter for about eight hours after adding the clarifier. Once the pool looks clean and clear, backwash or clean the filter to reduce the PSI.