How To Keep Dead Algae Out Of Your Swimming Pool (For Good)



Proper maintenance is essential to keeping your pool spotless, but the presence of algae can be a stubborn, uninvited guest that’s hard to get rid of.

With the tips in this article, you’ll be able to fully remove dead algae in your pool, and keep it away for good.

How Dead Algae Gets Into Your Pool

One day, you may notice the floor of your pool covered in dead algae, and chances are you’re not even sure that’s what it is.

Algae comes in a few different variations: yellow, green, black, and pink. If your pool experiences an algae bloom, the chlorine in water kicks in and tries to kill as much of it as it can. As it breaks down the algae, the offending particles are sent through the skimmer, and the filter removes them from the pool water.

So then, why is there a bunch of dead algae still on the floor?

This is because algae particles are so fine, some of them settle to the bottom of the pool, instead of being sent to the filter. When dead algae settles, it will look like a grey or brown dust has infested the floor.

Note: Dirt can sometimes be mistaken for dead algae at the bottom of the pool. If you can easily capture it between your fingers, it’s probably dirt. No stress, we have a separate guide on how to get rid of dirt.

Is Dead Algae A Problem?

Aside from looking aesthetically unpleasing, leaving dead algae in the pool means there’s particles still floating around in the water, which your filter will try to clean up.

This can lessen the lifespan of the filter (depending on how much algae is present. Additionally, dead algae can stain your pool surface if left on it too long.

How To Remove Dead Algae From Your Pool

There are solutions to eradicate algae from your pool. 

You should be aware that if the algae is still green, it’s not dead yet. Additionally, some pool owners use these methods and discover more dead algae the day after cleaning.

If any of those are your case, the pool still has algae in it and it will just keep coming back. You’ll need to shock the pool (or SLAM it), to make sure every single microorganism is obliterated.

Brush Your Pool

Brushing down the pool walls is going to be the first step you need to take, loosening and removing algae that’s clinging to them.

Depending on your pool’s finish you may need a soft bristle brush (for fiberglass or vinyl liner pools), or a steel bristle brush (for concrete and plaster finishes).

By brushing the walls, it allows the algae to float in the water where it can be pumped out and filtered, or fall to the floor of the pool.

Use A Pool Vacuum

The most effective tool to get rid of dead algae is a pool vacuum, and there are two ways you can remove algae using a vacuum.

The first method is the better (and easier) of the two, and can only be done if you have a multiport system, using either a suction-side or pressure-side vacuum. The multiport system allows you to send the waste water completely out of the pool.

To begin, set the system to its “waste” setting. Depending on the vacuum, it connects to either the skimmer (suction-side) or a dedicated suction line (pressure-side). 

With this “vacuuming to waste” method, the algae is vacuumed up, goes through the pipes and pump, and is then sent out of the pool system, bypassing the filter. This not only protects the filter from clogging, but also ensures algae won’t be reintroduced to the pool.

Also, it’s important to keep your skimmer basket and pump basket in place during this process, as they’ll help catch large clumps. If they’re removed, these clumps can clog up your pipes, and potentially damage your system.

The second method (if you don’t have a multiport system), is sending it straight through to your filter.

An older filter would be preferable as this process will render it useless when it’s over. Vacuuming algae through the filter can be less effective and a big headache as you’ll need to clean out the filter multiple times during the process.

As for vacuums themselves, the robotic kind are the best ones for this job as you just turn them on and let them do their thing.

However, manually vacuuming out your pool can get the job done just as well. It’s also important to make sure the vacuum won’t damage delicate pool surfaces like vinyl liners.

Use Flocculant

Adding pool flocculant to your water will coagulate the algae, clumping it up, and causing it to sink to the bottom of the pool. Flocculant works similar to pool clarifier, but clarifier clumps remain on the surface of the water to be skimmed off.

Sinking the clumps makes it easy for the vacuum to suck them up. However, only use pool floc if you’re vacuuming to waste, as these clumps will clog the filter and could cause potential damage.

How To Prevent Dead Algae In Your Pool

Preventing dead algae in your pool means preventing it from forming in the first place. It’s the best plan of action and means you may never have to deal with this pool pest if you stay on top of things.

Balance Your Chemistry

Regularly balancing the water chemistry (particularly the chlorine), is important because algae thrives in high pH environments that have low sanitization levels.

The ideal pH level for your pool is between 7.4 and 7.6. The total alkalinity of the water should measure between 80 and 120 ppm. Maintaining both of these will keep the water in a neutral state, which are ideal conditions for keeping algae away. 

When it comes to your sanitizing chemicals, chlorine should always be kept between 1 and 3 ppm, and shocking the pool on a regular basis is also important. 

Most pool owners will shock at least once per week. This process entails adding a mass dose of chlorine to kill off every single contaminant in the pool. When it comes to algae, shocking is a proactive measure to keep it away.

Phosphate levels in the water from swimmers and other organic matter can contribute to algae blooms, but if you’re on top water testing, and using an algaecide (see below) you can greatly reduce the chances of algae ever being an issue.

Keep Your Filter Clean

Maintaining the filter by cleaning it regularly is important not just for algae prevention, but for general pool maintenance as well.

The filter is usually working an average of 8 hours every day, so make sure you’re cleaning it out before it becomes ineffective and problematic.

Depending on your filter type, you can backwash a sand or DE filter, whereas a cartridge filter will have to be manually cleaned.

Use Algaecide Proactively

Algaecide is a pool chemical that will kill and prevent algae from growing in the pool, and is so effective as a preventative measure that some pool owners regularly add it to their water after its weekly shock treatment.

Dosing the pool with the right amount is critical, as too much can cause eye and skin irritation, as well as foaming that can damage your pool’s filter. 

It’s Dead And Gone!

The good news here is that dead algae in the pool is a curable problem. 

With the right know-how and proper prevention techniques, you can return your pool to a pristine state with very little work required.

Categories: Pool Care, Pool Problems