In all marine systems wastes are continuously produced. Fishes secrete most of the food in form of ammonia/ammonium (= NHx), protein, amino acids and fibers. To prevent fish and other animals against toxic concentrations, these substances must be eliminated or changed into harmless material.
With skimming or flotation proteins and some other substances are taken out of the system before the biological filtration works. The raising of nitrate and phosphate lowers with skimming. The water has lower concentrations of biological oxidizing substances. So the redox (ORP) is higher and the animals grow better.
What is the right skimmer for me?
First, the available space should be considered. Is there enough space for a large version or must all the techniques be build unter the aquarium?
High skimmers are more effective than lower models in any case because of the longer water retention time (at same water inlet flow).
This statement is only valid for the same procedure. If different methods or skimmer of different manufacturers are compared, it can be carried out, that a low model has a better performance than a high model.
Secondly the bubble creating system has to be chosen. If you compare hobby aquaristic skimmers, there is only one winner: the wooden air stones. With wooden air diffusers very fine and uniform bubbles are generated with low pressure (low energy). This point is extremely important for the performance of a skimmer. The disadvantage of air stones is the relatively short life time. Every 4-12 weeks the wooden air stones has to be replaced, because the performance of the wood is reduced by algal and bacterial deposits and decomposition processes. The use of ozone accelerates the decomposition processes.
In order to minimize maintenance work, AquaCare has placed the air wood in a separate module outside of the actual skimmer.
The injector, also known as venturi, is basically maintenance free. For smaller aquarium systems, the gas bubble size is slightly larger, the efficiency is a little bit lower. However, if a venturi is compared with an old wooden air stones the venturi will win. - For large skimmers with strong pumps, the bubble size is similar to the size of air stone produced bubbles. But this is only possible with high working pressures with more than 1 bar (10 meter water pressure).
Needle wheel skimmers can only be realized structurally as skimmers with a low height. The water level of the filter basin must be absolutely constant at the point where the needle wheel skimmer is installed. Slight variations in inlet pressure drastically change the performance. The big advantage is the low energy consumption of this type.
The Aqua Care injector skimmer types just need ONE standard pump for water supply and for bubble formation. The air stone types also need an air pump. The needle wheel types run only with special pump.
Finally, the question remains, what water flow should have the skimmer?
Basically: the higher the water flow rate, the more pollutants can remove the skimmer from the aquarium water, the better the water quality.
The skimmer does in fact compete with biological degradation processes in the aquarium and filtration system. The lower the exchange rate between the skimmer and aquarium, the more organics will be degraded by bacteria in the aquarium, rather than being physically removed by the skimmer.
The specified maximum aquarium sizes for each skimmer model are based on an exchange rate of 1.5 hours, ie the aquarium volume will theoretically run in 1.5 hours through the skimmer. If the aquarist feeds a lot and the fish density is high, the exchange rate should be increased. Rates of unter 0.2 hours for small aquariums are the useful maximum, for cost reasons. In systems with low organic load (little food, little animals), the exchange rate can be raised. However, it should be noted that the risk of oxygen deficiency, a bacterial bloom and low ORP value with the undersizing increases.
Comparison between the air bubble producing systems
|System||Air Wood||Venturi = Injector||Nadelrad|
|Quietness||very quiet||quit (sucking sound is reduced by muffler)||quiet|
|Bubble quality||extreme small and very uniform||small and uniform||extrem small and very uniform|
|Energy consumption||very low||low||very low|
|Mainenance||air woods must be changed periodically
(every 4-12 weeks)
|Venturi ist nahezu wartungsfrei||
|Sensitivity to changing water levels||medium||low||high|
|expendable part costs||medium||low||high|
Spare for your can be found here.
At places with low clearance (for example under the aquarium) Short Skimmers are useful unit to clean the water.
High Skimmers compared to Small Skimmers have a better performance because of the longer contact time.
Air woods produce smaller and more uniform gas bubble than injector = venturi or some dispergator pumps - they are more effective.
Injectors or venturis are nearly maintenance free systems to form very uniform bubbles for a skimmer.
Needle wheel skimmers are compact skimmers with high efficiency and low energy demands. Hower they need special pumps.
To realize certain projects you need accessories for skimmers: conversion kits, suction angles, spacers.