Pond Ionizers For Algae Control

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Written By Mark Washburn

Mark has 20 years of experience as a professional pond management consultant.

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One of the most recent devices to enter the pond care market is something called a pond ionizer and it promises to be a relatively affordable and safe system for helping to control algae in small ponds, water gardens, and pondless waterfalls.

Ionizers are best known in the air purification market and many “air ionizers” have been sold over the years. In simple terms ionizers use electrical power and current to ionize air particles. They add a positive or negative charge to these particles which is purported to purify the air.

A pond ionizer uses an electrical current which runs through what’s called an anode, which looks like a two-pronged tuning fork. The anode is made out of copper and is placed in the water flow line. By controlling the amount of electrical current going through the anode, the release of copper ions can be controlled and released within in the pond water itself.

Now you may ask, why is this important?

Copper Is Toxic To Algae

Primarily the main power behind copper, in terms of pond use, is that copper is toxic to many algae types (including string algae and single cell algae that creates green water) and it can be used to control and kill many algae blooms. This is why copper has been traditionally been one of the main ingredients of algaecide chemicals.

One problem with copper algaecides however, and in this discussion we’re talking about small pond treatments, is that small bodies of water are completely enclosed or confined ecosystems. With such small volumes of water, there is not as much room, or buffering, for mistakes in dosage, or other changes that can happen when algae is treated with a chemical.

Algaecides can and often are used in koi ponds and many times there are no problems however other people have experienced complete fish loss when products like this are misapplied or conditions are not supportive of the fish during the treatment. Because of these experiences many pond owners have begun to shy away from copper algaecides in smaller ponds and other algae control alternatives are always being considered.

How A Pond Ionizer May Help

One of the interesting and potentially beneficial features of a pond ionizer is that they have some type of gauge or dial in which the amount of current going to the anode can be controlled. As the current charge rises, more copper can be released and as the current is lowered less copper is added to the water. As yet, these are not self adjusting systems, but they can easily be managed by the push of a button or turning of a dial.

Ideally the pond owner would want to use just enough power/copper to maintain a clear, algae-free pond. This allows the use of the lowest amount of copper in the water, and it allows a longer life of the anode. Most anodes under normal conditions will last a year or longer and then it will need to be replaced to ensure consistent operation.

The water should be tested frequently for copper concentrations (using test strips) and after awhile one can generally get a feel for where the device needs to be set to maintain clear water.

A Few Precautions When Using A Pond Ionzer

A pond ionizer may sound like the perfect solution to algae control and they will certainly be sold as such by many manufacturers. However some precautions and preconditions need to be kept in mind to ensure safe and effective use.

First, it’s important to follow ALL of the manufacturers recommendations on the units. In most cases mention will be made of the importance of water parameters such as the pH, alkalinity, and hardness of the pond water. The basic numbers would go something like this. pH readings should ideally be in the 7.2 to 7.8 range and this can shift a good bit during the day, as well as when heavy loads of organic material are in the pond.

Perhaps more importantly is the amount of alkalinity in the water. The ideal range for use of an ionizer should be somewhere between 80 to 120 mg/L or ppm’s. Alkalinity levels dramatically affect the copper retention in pond water. A high pH and hardness will increase the precipitation or, in another word, the evaporation of copper in the pond. It either won’t last long enough to do much good or it will disappear so quickly that the copper anode will degrade prematurely.

On the other end of the spectrum, low alkalinity increases the duration of copper and this can be problematic when it’s constantly being added to the water, even in small amounts. In readings where the alkalinity is below 50 mg/L copper can build up to toxic levels over time and may cause harm to fish. In most cases a copper level reading of 0.2 to 0.25 should be safe for fish and be able to control algae.

And finally it needs to be remembered that although the control box and other components of the pond ionizer will last a long time, the one part of the system that will not is the anode. These will dissolve over time to the point where they will need to be replaced. In most situations, one should last for at least a year or possibly longer, however if a pond is fairly dirty, or the alkalinity is running on the high range, then it’s possible that the anode will degrade more quickly.

Current market prices for the replacements are running from $80 to $100 and that should be a consideration when comparing this technology to other options. Replacement of the anode is quite simple where the old one is unscrewed and the new one is put in it’s place.

My Recommendations On Where To Use A Pond Ionizer

Based on the current technology and the parameters mentioned above, some pond experts have concerns about using an ionizer in a pond with fish. To us, this concern is a valid one, despite the fact that many reports indicate that koi pond owners are using the systems with good results.

Our suggestion is to follow the axiom of “buyer beware”. If someone does their due diligence and insures that their water quality is fairly stable and within the range suggested for safe operation it’s very likely you will have success with the ionizer and experience no adverse problems. However pond environments are not static and can change from time to time so it’s a good idea to keep an eye on water chemistry and fish behavior to ensure a safe and healthy pond environment.

No fish?  Try A Pond Ionizer

In my opinion, a pond ionizer may have tremendous benefits for those with small ornamental ponds and no fish, or pondless waterfalls. Fountains and other water features may benefit greatly from an ionizer and routine cleaning and treatments can be reduced and in a sense, automated. In the readings that the devices produce, there is no indication that pets or other wildlife will be harmed from drinking the water. (As we noted above the main risk is for fish and only if water parameters our outside the suggested range.)

A pond ionizer can obviously have great benefits to certain pond and water applications since copper is a proven algae control mechanism. Nevertheless, they may not be perfect for every single situation but with some initial research and information such as we’ve provided here, many people will be able to decide for themselves as to whether it might be a good tool for controlling algae in their ponds.

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