Does Adding a Pool Blanket Promote Algae Growth?

Key Takeaways

Algae is always present in pool water at microscopic levels — it only becomes a visible problem when conditions favour growth, primarily low chlorine, warm water, and the presence of phosphates as a food source.
Prolonged rainfall and warm weather significantly increase the risk of an algae outbreak by diluting chlorine levels and washing phosphates and nutrients into the pool.
A pool cover does not cause algae growth on its own — but if chlorine levels are already low, the warmer water retained by the cover can accelerate an existing algae problem.
Algae can develop resistance to normal chlorine levels, meaning that once a bloom takes hold, simply topping up chlorine may not be enough — addressing the phosphate food source with an algae starver is a key step in treatment.
Effective algae treatment requires a combined approach: correct chlorine levels, a functioning chlorinator, phosphate removal, and running the filter for extended periods to clear algae spores from the water.

It’s not hard to understand why pool owners do everything they can to avoid an algae outbreak in their pool. Once algae takes hold, it can quickly spread and take over your pool.

What causes algae in pools?

Pool algae are ultimately the result of favorable growth conditions. These conditions include:

Low chlorine levels
Warm water
A food source (phosphates)

Algae is a pest organism that is always present (even a teeny, tiny microscopic levels) ready to bloom in the conditions that are right.

In general, it is easy to control algae however if you experience prolonged rainfall, excess runoff into your pool, and warm conditions - these will all predispose you to algae growth

Does a pool cover promote algae growth?

A pool cover will help to retain pool water temperature. However, if you are maintaining chlorine levels you should not have an issue with algae.

Using a solar pool cover will not make your pool go green. However, if you are having an algae issue then the warmer water can accelerate algae growth.

How do I fix my algae problem?

A green pool indicates a high concentration of Algae. Algae can become resistant to normal levels of chlorine and can then breed rapidly if the conditions are right.

In order to kill off stubborn algae, you should:

Ensure your chlorine levels are correct and that your chlorinator is working properly
Test for phosphates
Use an algae starver to kill the algae’s food source
Filter the pool for longer to remove algae spores

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