Your pool water is looking fantastic — clear, odorless and seemingly in perfect shape for you (your family and your friends) to enjoy a swim.  Then for reasons you just can’t seem to figure out, you start getting that icky white foam and scum  starting to form on the surface of the water.  Does anything kill the look of your beautiful crystal clear water more quickly?

Sure, you could skim the pool surface.  You could “clean it up.”  The real question, though, is what is causing it to appear in the first place . . . and how can you keep it from making a return engagement during your next pool party?

White foam appearing on the water surface is usually caused by one of three things (or a combination of them):

1.  Low Calcium

2.  High levels of polymer based chemicals (e.g., biguanides, polyquat algaedcides, some clarifiers)

3.  An air leak in the system  (MOST common cause!)

Among these three possible causes, the foam formation on your pool is likely caused by either the type of algaecides you’ve added to the pool water OR by an air leak in the system.

So what is the solution?  There are really two ways to fix this problem:  Change the type of algaecide you are using AND/OR check and fix any air leak issues.

How do you know which one (or both) of these is necessary?  And do you do one of these . . . or both?  To know the answer to these questions, you need to understand how they both work and how they relate to the problem.

Some algaecides sold at places like Walmart etc can cause foaming when too much is used.  Some algeacides, known as linear quats and containing the ingredient “Alkyl dimethylbenzylammonium chloride,” will tend to foam.

The level of foaming these will cause, however, tends not to be excessive and is fairly inconspicuous.  So this is not usually the primary cause of your problem.

If you have a vinyl pool, foaming will also tend to occur in pools that don’t have enough calcium in them.  Raising the Calcium Hardness (CH) to at least 100-150 ppm usually does the trick.

On the algaecide issue, try using PolyQuat 60 algaecide.  This is a situation of “you get what you pay for” since the linear quats are less expensive than the polyquat.  Algaecide eventually breaks down, though it will take over a week (that’s why they are added on a weekly basis). Shocking with chlorine will speed up the breakdown process.

If you do have an air leak in the return lines, it can lead to a higher level of pool water foaming and the creation of unacceptable water conditions.  This is not only the primary cause of your foam problem, but something you need to address right away.

In terms of checking for a possible air leak, there are a number of things to check for with this.  First, check the water level in the skimmer and make sure it’s not taking air.  Also make sure the return (eyeball) is pointed towards pool floor and away from the skimmer.  Next, check the hoses and clamps.  Then check the plumbing fitting.  Next check the pump strainer lid for cracks chips.  Finally check the strainer o-ring.  Remember an air leak is going to be on the suction side (at the nipple going into the pump) not the discharge side.

While an anti-foam can help, when you have an air leak your problem is more more mechanical in nature, and you need to fix it!  The good news is that this is not usually a major problem, and can be controlled and eliminated with the use of cleaning agents or enzyme products.

Address the root causes of your foam problems, and not only will you no longer have to deal with it . . . you’ll be done with it!

Filed under: General Information, Swimming Pool Chemicals, Uncategorized