Why Does Algae Grow?

admin — Mon, 26 Sep 2011 16:50:13 +0000

Algae is a major concern for pool owners. Algae is a one-celled plant that can grow in your pool if conditions are favorable. The most common myth concerning algae growth in pools is that it is ONLY a result of low chlorine (or its alternative). Although this is definitely a major cause of algae, it is not the single contributing factor.

Despite water treatment facilities, actual traces of algae may very well be present in the tap water that is used to fill your pool. Therefore, it is always a good idea to add an algaecide and to shock your pool after it has been filled or refilled. Yet another contributing factor toward algae growth are millions of microscopic algae spores that are carried by wind, eventually falling into your pool, where they will grow into outbreaks of algae if conditions are favorable.

A few of these favorable conditions are environmental. Algae, like all plants, need light and food in order to survive and grow. Temperature, humidity, sunlight, and nutrients (food) foster algae growth. Temperature, humidity and sunlight are self-explanatory. Nutrients consist of lawn fertilizers and other industrial products that are carried by wind and blown into the pool. Nutrients also consist of certain minerals that are already present in water. Since water chemistry relies on some of these certain minerals to be present, they cannot simply be removed from the water.

Here is a possible sequence of events: Algae spores will blow into your pool, where they are supported by temperature, humidity and sunlight. The algae spores then consume various nutrients. From temperature, humidity and sunlight, as well as from nutrients, the once unnoticeable algae spores have now grown into actual algae.

In addition to these environmental factors, other factors, such as limited water circulation, poor filtration, a neglect of routine pool maintenance, heavy bather loads, a neglect of overall water chemistry, neglect of shocking, and of course, insufficient levels of chlorine (or its alternative), also make conditions favorable for algae growth.

Algae is not harmful to swimmers. It just causes the appearance and integrity of your pool to suffer and occupies time to correct. If you do get algae, you are not alone; it has been seen in pools of some of the foremost authorities on pool care and maintenance. Rest assured, any algae can be killed, but not without a few days of continued effort and time. Therefore, it is best to begin with a discussion on the necessary steps to prevent algae growth. An ounce of prevention is worth a hundred pounds of cure.

Pool Water Chemistry, pH & Total Alkalinity

admin — Wed, 17 Jun 2009 18:27:13 +0000

However, th e relation ship between pH and total alkalinity (TA) is the most instrumental one that resides in your body of water…If the total alkalinity is in the right range, pH won’t be so volatile. If your pH is bouncing, chances are the TA is too low. TA is the real driving force to controlling the pH.

If a service tech or do it “yourselfer” doesn’t understand this relationship, poor water balance can result.

TA is the governor of pH. Don’t try to change the pH unless the TA is in the right range. The first correction is always TA…then you address any pH issue. And you may never have to change it if the TA is OK.

Here’s a look at exactly what pH and TA are, how they relate and interact and what service techs can do to keep it all under control.

What is pH?

Let’s go back to High School chemistry class (I’ll keep it painless and I promise there’s no test at the end).

pH is defined as a measure of water’s acidity or alkalinity. This is done by determining the power of hydrogen ions (H+) in the water. These ions are measured on a logarithmic scale from 0-14, with 0 being the most acidic and 14 the most basic or alkaline.

In simplified terms, pH is actually counting how many hydrogen ions are in the water.

Ideally, one is shooting for 7.4 to 7.6, slightly on the base side of neutral. This is a comfortable range for humans as well as the optimal pH range for chlorine to do its job.

Keep in mind that extraneous factors from both people and Mother Nature can alter pH levels. Things such as pool parties with high bather loads or heavy rainstorms, especially when the rain tends to be on the acidic side, all have an impact. In the wake of such events, we need to check water chemistry variables as soon as possible.

If the pH is allowed to dip below the 7.2 minimum standard, the water becomes more acidic or, as it is sometimes known, aggressive. This can lead to equipment corrosion, pool surface damage and inefficient sanitizer use.

If the pH rises above the 8.3 level, the pool may experience scale and high turbidity. In either case, skin and eye irritation can be an end result here.

It is important to monitor pH levels because the number drastically impacts the Saturation Index equation – a formula used to diagnose water’s chemical balance.

When the pH changes (for any reason), so does the Saturation Index.

That’s because although both TA and pH figure into the Saturation index, pH has a larger impact on it.

For example, a TA reading of 150 ppm uses a factor of 2.2 in the formula. A reading of 200 ppm is represented by a factor of 2.3. In fact, TA ranges from 100 to 300 ppm are represented by factors ranging only from 2.0 to 2.5. Consequently, it takes a major shift in TA ppm to affect the results of the Saturation Index formula.

On the other hand, the Saturation Index uses the actual pH reading in the formula – not a factor–so the change in the pH will have a profound effect on the outcome.

Whatever the pH changes, the index will change in the exact same amount. It’s a 1:1 factor. If you want to change the Saturation Index, lower or raise the pH.

When pH levels stray, most employ muriatic acid to lower it and sodium bicarbonate or soda ash to raise it.

However, it’s not always that simple. If all the variables are not in their proper ranges as well, particularly total alkalinity, it can be difficult keeping the pH within ideal limits.

The TA/pH relationship

Total alkalinity has an important relationship with pH in swimming pool water. But first, what exactly is TA?

Total alkalinity is essentially a natural buffering system that helps to stabilize pH readings. If pH is counting how many hydrogen ions in the water, TA is counting how many things in the water are capable of absorbing hydrogen.

Simply put, total alkalinity is made up of things that can take on hydrogen.

At higher pH ranges, total alkalinity is the combined presence of hydroxide ions (OH-),carbonate ions (CO3) and bicarbonate ions (HCO3).

However, in swimming pools and hot tubs, where the pH range shouldn’t stray too far from the recommended mid 7 range, TA remains strictly a bicarbonate.

TA is nearly 100 percent bicarbonate in pools unless the pH is in the 9.0range or better. You can define TA as the sum of alkaline salts and, in essence, to simplify things…the primary one is bicarbonate.

When TA levels are too high or too low, it affects overall water balance. For example, with water that has very low TA levels, the pH is under stabilized and will change dramatically whenever even small additions of chemical are made.

Water becomes more corrosive to plaster and metal fittings and heater elements. In conditions of excessive bicarbonate alkalinity, the pH is overstabilized and tends to remain around 8.3. The pH level is likely to bounce back to the 8.3 range even after acid is added. With TA and pH in such high ranges, dull, turbid water also can result.

I truly hope this pH and TA “overview” helps manage this interesting relationship – it can be a complicated one. I’ve really tried to break it down to something that isn’t terribly technical so it can be better understood.

Penguin Pools » water chemistry

Why Does Algae Grow?

Pool Water Chemistry, pH & Total Alkalinity