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13 PROTEIN SKIMMERS AND OZONE:
13.1 OZONE:
Ozone is one of the most misunderstood additives used around aquariums. This is mainly because few articles have been written about its function and use, and because even pet stores are not all that familiar with how to incorporate it safely in a salt water or reef system. Ozone is an allotropic and very unstable form of oxygen. Ozone does not exist on its own, it needs to be produced for you to be able to use it, therefore, hobbyists interested in injecting this gas, somehow, into their tank's water need an ozonizer. It cannot be bottled in pressurized canisters.
Because of its strong redox (2076 millivolt), much stronger than oxygen (1360 millivolt) ozone quickly oxidizes a great number of compounds, transforming them into compounds of a different chemical nature, often much less harmful than the original ones. This oxidizing ability is what underlies its use around marine tanks, and its injection into either protein skimmers or ozone pressurized reactors.
Ozone quickly breaks down because it is so unstable. Even in nature it cannot exist for any length of time, unless new quantities are produced continuously. You may have been exposed to ozone without knowing it if you have visited large waterfalls, coniferous forests, or in coastal areas during a massive die-off of seaweed. Ozone is also produced during large electrical storms. None of it can, however, be collected and stored. If you need ozone you will have to produce it right where you need it, and you will have to do so continuously to have an unending supply.
Excess ozone is harmful to all animals in the tank, to humans if too much is present in the air (1/10) mg per m3). Ozone also damages all non-ozone resistant tubing and hose it comes in contact with, and is neutralized in the process. Practically, what this means for the hobbyist, is that unless you use ozone-safe tubing you will lose a lot of the ozone you produce to the chemical reaction taking place with the tubing itself.
13.1.1 WHEN SHOULD YOU USE OZONE?:
If the water quality in your tank is low, which would be demonstrated by low redox potential levels and low dissolved oxygen levels, and a tank that does not really look in good shape, you may wish to consider using ozone to improve your water quality.
Tanks with these characteristics are usually in need of additional equipment to reduce the amount of organic material, alleviate the stress on all the filters because of the high load or poor water quality, and increase dissolved oxygen levels in the process.
Ozone will also keep parasitic disease in check. It may not cure the problem completely on its own, in a short period of time, but it will definitely kill off all free floating parasites that go through the skimmer and/or ozone reactor. Because free floating parasites are the ones that spread the parasites to other hosts, this is a plus.
Ozone also oxidizes nitrites, and can be used to cope with small amounts. Whenever you find nitrite you should, however, look for the real cause and deal with it, rather than using a patch solution such as ozone injection. Typically though, in tanks in which a fair amount of ozone is injected, no nitrites will be present, unless things get really out of hand. In such a case, major changes may have to be made to your system to bring it back in line.
13.1.2 HOW IS OZONE PRODUCED?:
Ozone is first produced by an ozonizer, or ozonator as it is sometimes called, and then mixed with water either in a protein skimmer, foam fractionator, or it is injected into an ozone reactor.
Two types of processes are used to produce ozone. Corona discharge units use very high voltage transformers (several thousands of volts) and transform some of the oxygen that is blown through a special tube inside the unit, into ozone. To do so efficaciously a good air pump is required. Wisa 200 and Wisa 300 pumps are, in my opinion the best suited for this process. Typically 1 percent of the oxygen passing through the tube will be converted to ozone, at 6000 volts.
Many factors affect the process, and generating ozone is not at all as simple as it sounds. Ozone generators can be very temperamental indeed. Moisture and dust in the air reduce the output of these type of units considerably. A loss of 50% or more is not unusual, especially since air around aquariums is usually extremely moist, over 90% is not uncommon. Dust inhibits the formation of ozone as well, which is the reason some hobbyists buy and install small in-line air filters.
A second process used, is to blow air over and by a specially constructed bulb that emits light in a specific nanometer range, and generates ozone while irradiating oxygen that passes through the unit as part of the air that is blown into it. These units too are rather touchy, as moisture, dust and temperature all affect the amount of ozone that will be generated, although to a lesser degree than in Corona discharge units. These units operate at regular house current voltages.
In both of these processes you must blow air through the unit itself, except if you have installed a venturi protein skimmer as the latter such in their own air, and do so through the ozonizer if you have installed one. In this respect, venturi skimmers can save you a good deal of money, as a strong air pump can cost quite a bit of money.
Several companies now offer a number of models to fit just about any situation you may be in. Small units from Sander producing 25 or 50 mg of ozone are available, and so are much larger units producing 250 mg, 500 mg, or even 1.0 gram from TAT. Regardless of which unit you buy, look for a long warranty because you may need it. Ozonizers can be very temperamental.
As indicated, moisture greatly reduces the amount of ozone your unit will produce. Adding an air dryer to your system is one solution, as it will pull moisture out the air that goes through before it enters your ozonizer. Problem is, air dryers need constant attention. The compound that absorbs the moisture needs to be dried itself just about every couple of days (and I do mean 2).
This is laborious, not as easy to do as you think, and many hobbyists quickly tire of it, and neglect the dryer. As a result, less ozone than is necessary is injected into their system.
The alternative is really simple. Buy a unit that produces about twice the amount you need, and do not use an air dryer. You will still end up with enough ozone and will not have to mess around with air dryers and the compounds in it, often calcium sulfate or silica gel.
Which unit is right for you depends on many factors. Mostly on the size of your tank, and the load you keep in it. Additionally the type of unit you need is determined also by whether or not you will be using an air dryer and an in-line air filter.
13.1.3 INJECTING OZONE:
Not much time needs to be spent on this as most hobbyists know that this can be done in two ways: through a protein skimmer, or with a pressurized ozone reactor.
After ozone is generated the mixture coming out of your ozonizer contains both air and ozone. This mixture is pushed into the protein skimmer and escapes into the water from so-called air stones. Since protein skimming happens more efficiently when the bubbles are small, appropriate air stones should be used, and they should be changed as soon as the size of the bubbles starts to increase. You may want to make it part of your maintenance schedule to change your air stones once a month. Limewood and oak seem to work best. The latter requires a stronger air pump than the former, because they offer more resistance to the air, however they make much smaller bubbles.
Some hobbyists want to use two small units rather than one, usually because they already have them. The correct way to hook them up is in parallel, not in series. The above diagram shows the correct method of hooking up 2 ozonizers.
When ozone is injected into a reactor, often just a plain acrylic cylinder filled with a medium to disperse the water, the process can be made efficient by raising the internal pressure of the cylinder. As the partial pressure of ozone is increased, it is forced more strongly into the water and a higher efficiency rate is achieved. What this means in simple terms, is that you get more oxidation from the amount of ozone used.
You will remember that earlier in the book my premise was that it does not really matter how much ozone you use, as long as none can be found in the water in the tank itself. This must, of course, be somewhat qualified! My recommendation is that you size the ozonizer you acquire to deliver 2 mg per gallon water in your system, and that you do not use it with an air dyer, and preferably install a redox potential controller.
Two milligrams per gallon in your system, rounded off to the nearest available size of ozonizer available, may seem high. It is not in my many years of experience with ozonizers. I personally use a 500 mg unit on a 135 gallon tank, but because of all the water in the sump and pipes, the true volume is really around 200 gallons. Even with that 500 mg unit I do not find any residual ozone in my system, other than in the water coming out of the skimmer.
Because no residual ozone may be present in the water that is in the tank - such could be very damaging to your corals - all the water coming out of the skimmer must be flowed over activated carbon before it remixes with the main water mass. Do not take this requirement lightly, especially if you follow my recommendation with regard to the amount of ozone used. As the activated carbon neutralizes the ozone, it exhausts its ability to do so. Change the carbon regularly. Once a month is a safe frequency.
13.1.4 USING REDOX CONTROLLERS:
As you "clean up" the water in your tank with ozone, and reduce the amount of pollution, especially organic pollution, the redox potential will go up. If you now adhere to sound feeding and stocking practices, it will take less ozone to maintain the water at that quality level, than it took to get it there in the first place.
This may seem like a dilemma. It is really not. If you operate a redox controller on your tank, the unit will shut your ozonizer on and off whenever the redox goes over or below the set point. Because of this automation no changes have to be made to your system, and you can let the ozonizer operate exactly the way it has done before.
If you do not use a redox potential controller you must use a different method, but you must use a redox potential meter, a device that will cost you between $50.00 and $100.00 depending on its quality. Buy one, or borrow one, or rent one from a pet store. You can rent such units from TAT as well. A one week rental will cost you $20.00, plus a refundable deposit of $30.00. The rental can even be applied towards the purchase price (price applied at the time of this writing, check with them for current pricing).
Proceed as follows, do not switch the ozonizer off:
Although this exercise may be somewhat time consuming, and although you may have to repeat it several times, it certainly is less expensive than acquiring a redox potential controller of good quality.
Not only will it allow you to operate your ozonizer more efficiently, but it will, in addition, give you a better understanding of what is going on with your tank, which in itself is a plus.
13.1.5 CONCLUSION:
Whether you like it or not, the use of ozone will greatly improve the quality of the water in your system. Used as explained in this chapter, ozone's mystique is no longer a problem, and it can safely be used, even by a novice.
Used in the amounts suggested it will bring the quality of your water up to levels where it has not been before. Both the animals and the appearance of your tank will reflect it and the overall result will be a much more vibrant looking aquarium.
Read up on ozone in other books if you still feel uncomfortable with it. Talk to others who have used it for a long a time, or call us at Aardvark Press. We will gladly help you.
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