| NetPets® |
Water Additives Used :
Many water additives will change the way in which the water foams. Some can really make the skimmer get totally out of hand. Such foam is mostly water that does not contains the extra material that you want to skim out of the tank.
Before using any additives, it is important that you try out a very small amount of them, to ensure that you will not have to re-adjust the skimmer. Many products, unfortunately, fall into this category. Running a skimmer with 6 or more inches of very wet foam at the top is counter productive. If you must use these elements, switch the skimmer off for a while (several hours, to over a day for some).
Certain trace elements will not make your skimmer foam more than it normally does. One such products is sold by T-A-T, but there are others.
Once you understand what will affect the operation of your skimmer, and made the necessary adjustments, you are ready to optimize the amount of water flowing through the skimmer. We assume, for this example, that you have followed the checklist, and that you have the right kind of skimmer, the one suggested and recommended for the type of tank that you keep.
- Take a small jar that can be closed airtight. The latter is very important. You must be able to fill it, and close it so no air whatsoever can enter the jar. - Perform a dissolved oxygen test. Note the result. - At the same time as you take water for your dissolved oxygen test, fill another jar completely, making sure that no air is trapped in the container. - Store this jar with the water for 48 hours, in dark place. - Flow the content of the aquarium once, per hour, through the skimmer. For ease of calculations use the rated content of your tank. - Let the skimmer run for 48 hours. - Perform a dissolved oxygen test on the tank water, and a dissolved oxygen test on the water you stored. - Compare the results of the the oxygen test you did two days ago with the one you just did. If it is lower, you are not skimming enough, and either your skimmer is too small, or your load is too high. - Now test the water you put away for 48 hours. Compare the result with the Dissolved oxygen level you had the day you took this sample. Write down the difference. - Refill the jar with aquarium water, and store for 48 hours. - After 48 hours test the sample. Write the number down. - Compare this result with the one you got when you took the sample. Note the difference. - If you are running enough water through your skimmer the oxygen deficit should have gone down.
To illustrate this :
Flow rate Day D.O. D.O.(48) Difference 1 x tank 1 6.80 4.50 2.30 3 7.00 4.80 2.20
At the above flow rate your tank's organic load went down; the skimmer removed it. How do we know that ? By looking at the dissolved oxygen (48) numbers, and comparing the first one you had with the second set. We are not interested as much in total dissolved oxygen, as in the difference between the first and second number. Notice that for the first set the difference was 2.30 (the deficit), and in the second set it was only 2.20, slightly less. Not much, but still slightly less.
Another example :
Flow rate Day D.O. D.O.(48) Difference 1.2 x tank 3 7.00 4.80 2.20 5 7.20 5.60 1.60 1.5 x tank 7 7.50 6.20 1.30
All numbers in mg/l. Numbers were achieved on a 40 gallon reef tank, using a 30" x 6" skimmer from Thiel-Aqua-Tech. Tank had a heavy load of fish and invertebrates.
What you now want to do, is to change the flow rate through the skimmer and determine at which level, the difference between the D.O. test, and the test done on water taken at the same time, but stored for 48 hours, is the smallest. At that level the skimmer is removing the most organic material, and is running more efficiently. The reason for this is, that the higher the organic load left, the more oxygen will be consumed by bacteria in the 48 hour elapsed period, the greater the difference in the D.O. levels will be as well.
This may not be the quickest way to determine optimum flow rates, but it is certainly a method that is both easy and inexpensive, does not require elaborate equipment, and can be used by any Hobbyist.
Protein skimming is a special form of filtration, and the name is a misnomer. Skimming removes more than just organics (protein). Trace Elements, vitamins, fertilizer, and other elements will be removed as well. You must be aware of this, and replace these elements on a regular basis, lest you will run a tank with a deficit of beneficial compounds.
How much you should add is very hard to know, but add you must. Refer to the recommendations made by the manufacturers of the products that you use. If, in addition to a protein skimmer, you also inject ozone, you will need to add even more additives, as ozone breaks these compounds down rather quickly.
If you happen to be in the market for a skimmer and a filter, consider buying a trickle filter that incorporates a Venturi skimmer. Your total expenditure will be less, and you will have a skimmer that not only fits underneath the tank, but that works as efficiently as a 4 foot column (applies to T-A-T models).
Keep the following in mind when selecting and running an outside skimmer:
- Size the unit properly. Use the checklist as a guide.
- Change the airstones every 3 to 4 weeks.
- Adjust the water level so you produce only dry foam.
- Try to determine the optimum flow level.
- If you don't, flow 1.25 to 1.5 times the tank's content through the skimmer.
- Empty the cup regularly, or make it run into a bucket that you then empty.
- Adjust the water level in the skimmer as needed. This means and we have said it already, monitor your skimmer on a regular basis.
Recently, more efficient and more compact protein skimmers, foam fractionators, have appeared on the market. Of the three models that were available at the time of this writing, only one was made in the United States.
Venturi skimmers do not require an air pump, but can be operated with one if you want to. The principle behind these skimmers has been around for along time. As water is forced through a special fitting, a differential pressure is created, and this differential pressure sucks air into the water stream, and breaks the air up in very small bubbles, giving the efficient skimming we instanced.
The more forceful the water is pushed through the Venturi valve, the greater the differential pressure, and the more air is being sucked in. Water flow levels needed vary, depending on which Venturi skimmer you purchase.
It may happen that the pump you are using to run your Venturi skimmer, is not pushing enough water through the Venturi. As a result not enough air for efficient skimming is being pulled in, and you have the impression that your unit is not working properly. There are two ways around this : one, push more water through the Venturi, and if that is not possible; two, attach a strong air pump to the intake of the Venturi valve and blow air into it. This will compensate for the lack of high water flow.
Venturi skimmers are appealing to many Hobbyists because they are compact, and will fit underneath the aquarium cabinet. If you plan to use ozone with such a skimmer, make sure that the unit you are planning to acquire can function with it. Some cannot, as a lot of Hobbyists have found out.
A Venturi skimmer's efficiency is determined by the quality of the "venturi" valve, and how it is constructed. Ideally it should have a Pitot tube inside. If not, the venturi still works, but may not draw air in as forcefully.
More details on "Pitot" tubes can be found in Advanced Reef Keeping Made Simple. Regardless of whether your skimmer has such a tube or not, more air can always be blown into the skimmer by means of a strong air pump, if such is necessary. Remember: the amount of water going through the skimmer is important, but what is more important is whether or not the skimmer operates efficiently, and that is determined by the mixture of air/water, and the size of the bubbles you generate. Some companies, e.g. Thiel-Aqua-Tech uses both "molded" and hand made Venturi valves. Molded valves obviously are more efficient but are more expensive.
If you have to make a choice between a columnar and a Venturi skimmer, the Venturi model will, in most cases, outperform the columnar one, especially if it is equipped with a molded venturi.
Conversion and Hang-on Units (Biological filters)
Several manufacturers now offer so-called conversion units, mostly geared towards the smaller tank, e.g. the 30 to 70 gallon range. Many will perform an excellent job for your aquarium, as long as you select the correct size for the tank you have, and the load you will keep.
What is most important in those units, is that the water is dispersed very evenly over all of the biological materials inside. Because you have less of it, you must use it more efficiently. This is where drip plates with many small holes are a must. It is probably best to actually "see" the unit before you buy it. Look through the magazines as well. Pictures can tell a lot too. One really excellent unit is made by World Class Aquarium, of Brooklyn, New York.
Several commercial units are available. Moe (1989) describes how you can make one yourself in "the Marine Aquarium Reference". That 500+ pages book contains a wealth of such information, and is well worth the investment of around 22.00 dollars. Look through the magazines, or at your local Pet Store, and you will usually find a selection of them.
Because of the reduced size these filters do not necessarily accommodate all of the extras that we have recommended earlier in this book. Select one that has as many as you can find, and supplement the system with additional filtration means, e.g. canister filters filled with Poly Filters, activated carbon, X-nitrate, or similar products that we have already described.
In these filters we recommend that you use plastic filtering material that definitely does not trap dirt . Since this is a smaller filter, you certainly do not want to have to clean it and destroy a great deal of bacteria in the process. Cubes, Blocs, Spheres, Techs, Balls, Packs, disks, and the newer Super-Techs will work well. Blocks and Cubes are especially well suited.
Remember : you must blow air into the biological chamber as this will greatly improve the efficiency of your filter. The biological processes that take place in the bio-chamber require a great deal of oxygen, because the bacteria that "perform the work" are aerobic. Not blowing air into the filter is, to make an analogy, like driving your car in third gear and never moving up to fourth or fifth, or, back to our filter, only using part of the available biological activity of the filter.
Make sure too that the conversion unit is of the "trickle" type, and not a submersed biomedia type. Although the latter units work too, of course, they operate at much lower levels of biological activity than the other types.
[Albert J. Thiel requests that you make a $5.00 donation to the New Mexico School for the Visually Handicapped Children, 1900 North White Sands, Alamagordo, New Mexico 88310 (or other charitable group) if you download the entire book. This would be in lieu of the standard purchase price for this publication.]
| Back to Table of Contents | Back One Chapter | Top | Next Page |
 NetPets® Main Page |  The Fish Center |