Revising part two: Filtration

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Revision questions and answers for week two's filtration module.

In this quick revision, the important thing to remember is that you are aiming to pick out the specific facts relevant to the question. The final test at the end of the diploma will not be the kind of test that requires hundreds of words — no part of it runs as an essay. Instead, it will be conducted in the form of multiple-choice answers to a series of questions.

The layout below is a selection of practice questions, each of which probe your knowledge on the module you have just covered. Though they’re not laid out as multiple-choice questions and answers, they are designed to stimulate your mind to re-explore some of the main areas you’ll be tested on.

1) What are the three main categories of filter function?


2) What is the main purpose of a mechanical filter?


3) Which two pollutants are biological filters intended to control?


4) What are the three necessary criteria for a surface to become biologically active?


5) What is the collective name of bacteria that can utilise organic carbon as a food component?


6) How do autotrophic bacteria mainly develop in aquaria?


7) How quickly can heterotrophic bacteria double their population?


8) What does an ion exchange resin media do?


9) In normal use, how often is it advised to replace carbon filters?


10) Is fish-in cycling safer or more dangerous than fishless cycling for fish?


11) All things being equal, will filters mature more quickly at 28°C or 15°C?


12) What effect will a pH of 4.0 or lower have on biological filtration?
























1) The three main categories of filter are mechanical, biological, and chemical.


2) The purpose of a mechanical filter is to remove of particulate waste.


3) Biological filters are intended to control ammonia and nitrite.


4) The three necessary criteria for a substrate to become biologically active are access to oxygen, access to food, and omission of light.


5) Bacteria that can utilise organic carbon as a food component are known as heterotrophic bacteria.


6) Autotrophic bacteria mainly develop through binary division.


7) Heterotrophic bacteria can double their populations as quickly as 20 minutes.


8) Ion exchange resins swap one chemical for another.


9) In normal use, carbon filters should be replaced every 4 to 6 weeks.


10) Fish-in cycling is more dangerous to fish than fishless cycling.


11) Filters will mature more quickly at 28°C than 15°C.


12) A pH of 4.0 or lower will inhibit biological filtration.