Aquascape : Aquarium protein skimmers
Every hobbyist desires a crystal-clear water, including the surface! Dissolved organic compounds, oils & other agents form slicks on the surface, they are a nuisance that only special devices can eliminate them.
After a little discussion about aquarium protein skimmers in the previous article, maybe you are wondering, how these devices work to clean the water's surface? Or is it really can be used in a freshwater aquarium?
How aquarium protein skimmers work?
Protein skimmer is a water purification device that seperates the dissolved organic+inorganic matter, either from the water's surface or any water levels by using microscopic bubbles. Water that entering the device will be aerated. Bubble size is a key to a successful aquarium skimmer and various advanced methods such as a vortex system or a needle-wheel system are used to create the microscopic bubbles. Surface tension -which is friction between the oxygen bubble and the input water- attracts waste to stick to the bubbles & carries it up through the column of water, and when the bubbles reach the surface, they burst, depositing the waste into a collection cup. This collection cup is designed to keep the accumulated waste from slipping back down into the water column.
Can an aquarium skimmer be used in a freshwater aquarium?
Some opinions said that the protein skimmer can only be used in a saltwater aquarium, due to the very nature of saltwater which has a high water density/salinity (34-36 ppt), high degree of water hardness (KH around 7-10°dKH) and high pH level (pH around 8.2-8.6).
At first, I was also in doubt about the effectiveness of using aquarium protein skimmers in freshwater aquariums, but I tried it anyway. It appears to be quite effective to overcome the water's surface problems, the oil slicks disappeared and other particles stick to the collection cup. Although it doesn't produce a foam froth as much as in the saltwater usage, it does work anyway to dump the surface waste into the collection cup.
Based on the placement of the aquarium protein skimmers, it can be divided into:
In-tank aquarium skimmer
These aquarium protein skimmers are usually set in a rear corner inside the aquarium. They have limited designs and models, such as:
• Co-current skimmer. This aquarium skimmer draws water from the open-bottom where the air stone is mounted - limewood is usually used to create the froth. This protein skimmer uses the volume of air bubbles rising in the column to contact with the water, the duration of the water is in contact with the bubbles is important here. By lengthening the column, the duration will increase, so more water could be processed and more waste removed. Choose the tallest one for more effective skimming. Since this model draws water from far below the waterlevel, it's not effective for surface cleaner! even by operating a small powerhead to create the surface agitation in order to make the waste and oils dissolved/ mixed with the rest of the water and available for removal by the protein skimmer.
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Counter Current skimmer. Counter current means upward flow VS downward flow. By countering the flows, the contact time between the water and the bubbles can be doubled! making a more effective skimming process. Downward flow is water to be fed through the top of the skimmer chamber by using a water pump, a powerhead, or a surface-overflow set up. While upward flow is air-bubbles provided by an aeration through the air stone that rise in the skimmer chamber, which then carry the surface waste into the collection cup for disposal. This type of aquarium skimmer can answer our need for surface cleaner, since it can suck the water's surface; i.e. through the surface overflow technique.
In-tank set ups can be an eyesore to your planted tank, and the sticking-up collection cup may get in the way of other equipments within your aquarium canopy; i.e. lighting equipments.
Hang-on Tank Mount aquarium skimmer
If you don't want an aquarium skimmer that sits inside your planted tank, you can use a Hang-On Tank Mount aquarium skimmer.
These aquarium protein skimmers are attached behind the aquariums, they take up spaces between the rear tank and your wall, so you should make sure that there's enough room to install it before you buy one. And since the tube of Hang-on aquarium skimmer is located outside the aquarium, there's a risk of collection-cup overflows that can ruin your aquarium stand, floors or carpet. What a mess!! That's why it's very important to install a drain plug in the collection cup, with a drain hose exits into a large capacity container behind the aquarium stand.
There are 2 types of Hang-on Tank Mount aquarium skimmer:
Venturi driven protein skimmer is powered by a water pump or powerhead with venturi to create and inject air bubbles. Then the injected air bubbles create a vortex of water and a foam froth in the bottom of the chamber. This vortex greatly increasing the amount of contact time and waste collected.
Pinwheel/Needlewheel protein skimmer is driven by a water pump or powerhead. It works by drawing air into the needle-wheel style impeller system. The needle-wheel chops air into the water, creating a bubble rich froth that is then pushed into the chamber of the skimmer.
Usually the water is fed into the skimmer chamber by using a powerhead or a water pump (with/without a venturi use) that is placed below the waterline. This pump position makes the aquarium protein skimmers unable to skim the oil and other dissolved organics that float at the surface and these harmful accumulations are left unattended. To place a small powerhead just below the surface in order to create turbulence and make the accumulations more soluble to be sucked by the pump to the skimmer, will NOT work!!.
Note: Water agitation only can't break the surface slicks, it should be help by an aeration. The air bubbles from an aeration will break the surface slicks first, and then the water's surface is stir-up by the agitation. But an aeration in a planted tank is prohibited, right? especially during the day!
So ... what to do? For all non-surface feeding skimmers, you can attach the surface extractor device to your powerhead/water pump's intake, it will slurp the water surface for removing slicks and debris. Gentle surface flow is needed to direct the water to the device's intake.
Usually a surface extractor is designed as an addition/attachment to external filters and can only be compatible with its own brand. To make it work with your powerhead/water pump, you can just simply connect the surface extractor to the pumps' intake by using a short segment of flexible hose, a L(90°) connector, etc., of course with a little creative modification.
HOB (Power filter) with built-in surface skimmer
HOB+Skimmer is a breakthrough concept in a power filter design, a total system, combining a protein skimmer with chemical, mechanical, and biological filtration techniques. It is basically a protein skimmer and an aerating power filter in one compact, easy-to-use unit:
- It is easy to operate. The unit hangs on the back of the aquarium, just like a standard power filter and provides three stages of filtration.
- Innovative, built-in skimmer Automatically adjusts to aquarium water level (Patented Floating Surface Skimmer Technology) for effective removal of Surface Film (oily, organic film and scum) & Dust from the surface.
- Three-level intake system extracts water from the surface, middle, and bottom for complete aquarium filtration. Includes 2 filter cartridges for efficient, mechanical, chemical, and biological filtration.
- Improves Oxygenation & Water Circulation.
They are for freshwater or saltwater aquariums.
In-sump aquarium skimmer
A sump is nothing more than a reservoir placed beneath the main display tank or in the aquarium cabinet where it can be hidden. Within the sump, an aquarium skimmer is becoming part of the aquarium filtration with many placement-variations. Sump systems do require a specialized installation and plumbing knowledge that won't be discussed in this article. If the sump is placed inside the aquarium cabinet, the size of the aquarium skimmer is limited by the height of the cabinet!
All of the aquarium protein skimmers except the In-sump type have the same disadvantage: the tube disturb the aquarium's appearance and they all take-up a lot of space (either inside or outside the aquarium). If it's a great concern for you and you also don't want to install a sump, Don't worry, you still can eliminate the surface problems by using another devices which will be explained in our next inspiring article! Or just use above explained HOB (Power filter) with built-in surface skimmer.
See you in our next articles.