Don’t Close your pool GREEN!

dont-close-your-pool-greenI know that some of you are secretly glad about closing the pool soon. One less thing to do around the house.

It’s tempting and altogether common, that pool maintenance slackens at the end of the season. Some pools are nearly abandoned the month before closing!

Getting your pool back in shape for closing is a great way to ensure an easier pool opening, while protecting your smooth, soft and stain-free pool surfaces.

Some of you may be short on time and patience, however ~

“The pool cover will block out the light, and kill the algae, right?”

Closing a pool that is green with algae, or dirty with debris or with water that is unbalanced, leads to heavy staining and saturation of the water with dead algae cells, which makes it easier for subsequent generations to grow.

Many forms of pool algae can grow accustomed to low light, and some can substitute aqueous starch or sugar, to acclimate to complete darkness.

“The cold water will kill the algae then, right?”

pool-algae-growth-rate-chart-at-varied-water-temperatureAlgae becomes dormant at low temperatures, and the rate of photosynthesis and growth is very low once temperatures drop into the low 60’s. It’s for that reason that we have suggested on this blog to wait until your pool water temperature is 65° before closing the pool.

Algae growth is stopped at temperatures below 40° F, but some algae can continue to survive, and like weeds in a lawn, can go dormant over the winter, coming back to life in early spring, weeks before you open the pool.

“Why Clean the Pool Twice, am I right?”

Why clean it now, and then again when you open? Two reasons – leaves, debris, dust and dirt mixes with salts and minerals in your pool and can make ugly stains during a long winter without circulation. Secondly, any organic matter in your pool uses up the winter chemicals quickly, leaving no reserve for springtime.

“What If I Drain & Clean the Pool next year?”

For concrete pools that are going to be drained and acid washed next year anyway, or if you are certain you’ll replace the pool liner in the spring – then you may think it quite clever to close the pool green, and without any winter chemicals. However, excessive algae growth from high pH and low sanitizer can damage pool plaster or steel pool walls, and other underwater pool materials.

“Can I Drain it Now, and Refill it in Spring?”

All swimming pools must be kept mostly full during the winter to prevent damage to the walls or popping of the pool from hydrostatic pressure. It also protects  plaster from cracking and vinyl from shrinking.

“It’s Too Late, I have to Close the Pool Now!”

stick_figure_help_button_text_10646-1If it’s urgent that you close the pool without the water being clear and balanced, and the pool spotlessly clean, I understand this happens sometimes. In addition to winterizing the pipes, or filling them with pool antifreeze, take these steps as a minimum:

  1. Lower pH to 7.2, brush and skim to distribute
  2. Shock the pool or add a winter chemical kit
  3. Cover the pool tightly to block out leaves and sun

Green pools should always be covered, for safety reasons – uncovered green pools are more hazardous as the floor of the pool is not visible.

A safety cover is the best type of pool cover for winterizing, or for protecting a pool that is not regularly maintained, due to lack of funding or an empty house.

In the long run, closing a pool green or filled with debris will create more work and could permanently stain or damage surfaces. Protect your pool with clean and balanced pool water, a winter kit, and a strong pool cover!

Davy Merino
InTheSwim Blog Editor


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