Swimming Pool Blog

Preventing a Green Pool Opening

Holiday Vacation Planning
by Mark Garcia September 21, 2013

Problems that Create a Green Pool Opening

prevent this from happening to you!

If your pool opens up green every spring, this post is for you. Here's some ways to prevent a green pool opening, and be confident of a blue pool when the cover comes off.

Pools open green when the winter cover is not keeping out debris, the water chemistry is poor, and there is inadequate sanitizer.

Even if you open late, and even if you have a mesh safety cover - you can skip the stains and discoloration by avoiding these problems with the pool cover and the winter water chemistry.

Winter Pool Cover Problemssolid safety cover

If you want to open to a blue pool every year, I have a simple solution. Install a solid safety cover, without drain panels.

I've opened 1000's of pools in my time, and those with a solid-solid safety cover would always open up blue, and usually crystal clear. Keeping out winter air pollution, pollen and dust, by blocking all rainfall and snowmelt keeps the water in balance and conserves winter chemicals.

Raised Walls: For pools with a raised wall, for a raised spa or higher deck level, there are two ways to install a safety cover - in-the-wall or up-and-over. In-the-wall installations may not fit so well, and fill with leaves during winter. It's always best to go up-and-over on pools with raised walls.

ugly solid coverFloating solid pool covers, with water bags, can be a very good cover, if they are conscientiously pumped off, and kept clean. They are prone to easy holes however, from sticks or animals, and when they get a hole in the middle of winter - if you aren't maintaining it very well, a sinkhole can develop and spill dark green matter into your pool.

The problem with floating solid covers, is that they never fail to fail, right in the middle of winter, or when you're struggling to remove that last bit of mucky water from the surface  - rip! there goes a seam, or a small hole opens up to a gash.

Winter Water Chemistry Problems

If you close your pool clean, with water balanced, and a winter kit, or an appropriate amount of sanitizer and algaecide, you can expect those chemicals to last about 5 months. .

For pools that open green each year, something extra is needed. I use Pool Magic with Phos Free for problem pools. Pools that have green spring openings usually have a phosphate problem, although they may also have cover problems and/or water level problems.

The most important thing to note with winter pool chemicals is that more will be needed if you have contaminants entering the pool, be they full sized leaves, or dust that washes off the trees. More will also be needed when the temperature of the water rises.

Water Temperature Problems

When your water temperature drops into the 50's and colder, most danger of algae is suspended. Chemicals also last longer when the water is cold. But when the water temps warm up in the spring, your chemical protection can be quickly depleted. Above 65 degrees, and winter chemicals in an unfiltered pool will become active and begin to work themselves to death.

Winter chemicals are really most needed just after closing and just before opening. During the colder months, very little is going on under the cover, but as things heat up, more chemicals are consumed, and more organisms spring to life. Mesh covers will allow some sunlight to pass through which can warm the pool surface.

Mesh Covered Pool Problems

mesh pool cover leaf soupMesh safety covers and solid covers with drain panels, let in all sorts of microscopic gunk during the winter. If the pool water level is allowed to touch the underside of the cover, leaves get stuck on the cover, and a tea bag effect is created, leaching the tannins from the leaves to create a leaf soup, staining pools and consuming chemicals.

Water balance can change dramatically in a mesh covered pool. It should be checked at some point during the spring. It's a good idea to add an extra dose of shock or algaecide (but not both) as the weather begins to warm up into the 60's.

My advice is the same to all mesh covered pool owners.

'In mid to late spring, or about a month before you plan to open the pool:'

  1. Remove springs on both sides of the pool. Fold cover onto itself in the center.
  2. Use a small submersible pump or a siphon to lower water below the tile.
  3. Check and balance the water chemistry and shock the pool, or add a Qt. of algaecide.
  4. Find the chlorine floater and fill it with tablets. 
  5. Brush the walls on both sides of the pool.
  6. Put the pool cover back on tightly.

If you open up to a green pool each spring, think if you have any of these problems above, Fixing one or more of them can give you a beautiful blue pool next spring!


Thanks for Reading!

Mark Garcia