This post was contributed by Sophie Leadsom of Saltwater-Suckers.co.uk. Sophie is an experienced marine fishkeeper and used to specialise in breeding seahorses (she has successfully bred kuda, comes, reidi, barbori and dwarfs, and at one time had 12 marine tanks running concurrently). She is also an ecologist by profession and specialises in designing and building wetland nature reserves. This post is part 3 of a four part series on getting started with marine fish keeping. In my last post we focused on how to cycle your new marine fish tank. Cycling your marine tank involves establishing the full suite of bacteria that will create the foundation of your tank. These are the bacteria you will need to nurture and keep happy. Once they are established, they will be the underlying make or break of your tank, as they break down all the 'nasties' such as ammonia, nitrite and nitrate, and help to create the environment in which your marine inhabitants will thrive. Establishing these bacteria is essential to the 'biological filtration' of your tank, a process which emulates the natural cycles of the ocean by ensuring oxygenated water flows over the bacteria on the rock.

However, our tanks are not the ocean and when we introduce our last 'must have' fish we are often close to overloading these bacteria to where they can no longer cope with the bioload. If the bioload becomes too high we will start to see a change in the tank. Nitrate may start to rise and your aquarium water may start to lose that pristine look and take on a yellow hue. If this happens, don't panic! You can usually accommodate your last 'must have' fish and keep your water parameters in order, but your tank just needs a little bit of extra help. The nitrogen cycle as carried out by your happy bacteria is known as biological filtration, but there are other types of filtration that can give those bacteria a little helping hand - these are known as mechanical and chemical filtration. Mechanical filtration is defined as the process of extracting particulate matter from the water column. This is usually done by drawing the aquarium water through something like a filter sponge or filter floss.

In your tank, sometimes you’ll find your water or rocks will look 'dusty'. Maybe you have noticed your rocks are dirty and you have scrubbed them; or perhaps you have disturbed your sand-bed and the tank is cloudy with thousands of unwanted little particles after you have done your routine furtling. (My routine furtling tends to involve a lot of turkey basting of the rocks and subsequent cloudy water). In these cases, mechanical filtration is a good way of removing the unwanted particles from the water column so your water is back to its pristine cleanliness. The filter will draw water into itself, run it through a series of sponges or filter pads and put it back in the tank, minus the irritating particles. The main mechanical filtration method is to use a filter - “how obvious” I hear you freshwater fish keepers scream! However, using an internal or external filter on a marine aquarium is often met with great debate in the marine fishkeeping world. If you have kept freshwater fish you will be well versed in using filters to maintain your water quality but marine systems are a little different.

Marine tanks rely on the bacteria living in the rock for their filtration, the filtering bacteria having set up home on the available surfaces within the tank. The balance between water flow and bacteria efficiency is delicate and cannot be met within a filter. What this means is, if you try to filter a marine tank in the same way as you filter a freshwater tank (by keeping all the sponges etc. within the filter), the filtration bacteria will start to establish in the filter and begin causing you nitrate problems because the filter can’t function efficiently.fish tank heater melbourne You will sometimes hear of people putting live rock rubble in filters thinking they are increasing the filtering capacity of their tank. fish tank filter motorThis doesn’t work unfortunately - all you will do is create a trap for tank debris that will cause you all sorts of problems, as the bacteria can't function effectively and will basically suffocate.fish tank heater on ebay

The point is, by all means use a filter on your marine tank, but make sure you don't allow the bacteria to become established. This is best done by making sure you keep the mechanical filter somewhere it can be easily cleaned and maintained. Any sponges within it should be thoroughly cleaned weekly before any bacterial reactions start to take place. fish tank second hand saleAlthough slightly controversial, I have always advocated washing marine filter sponges weekly in tap water. fish tanks for sale in coffs harbourI hear you say, but everyone has already told you time and time again that you can never have tap water near your tank. fish tank price in sangliYes, that's right but.... Fluval External Canister Aquarium Filter available at Swallow Aquatics

Tap water has chlorine in it. In any decent quantity this will begin to wipe your tank out, but in minute quantities, the chlorine actually acts as a disinfectant. If you wash your sponges out in tap water, it will kill any bacteria on them so they can start fresh before any problems start. I used to use tap water to disinfect my baby seahorse rearing tanks (seahorses, by the way, are really, really sensitive, to, well, everything), so I know that it works as long as it's in small quantities. So by all means use an external or internal filter to remove particles from the water, just make sure you keep it, and whatever is in it, clean! Chemical filtration is often considered alongside mechanical filtration, as you will probably use the same vessel for both. Chemical filtration is the removal of dissolved nasties in the water, such as organics, by using, well, a chemical. The most common chemical filtration medias are carbon and aluminium based substances that remove organics and phosphate.

These often come in pellet or granular form and are either already in bags to be placed directly in an area of water flow, or you can sandwich them between pieces of filter floss and place in the filter. These will help the bacteria to keep your water quality pristine and ensure you can have your last 'must have fish' and still keep your tank pristine. Fluval Sea Total Clear Chemical Filter Media available at Swallow Aquatics Mechanical and chemical filtration can be a useful addition to your marine aquarium if used carefully, but always remember that biological filtration using live rock and happy bacteria will always be the heartbeat of your tank. So even if you use a filter, carbon or phosphate remover, never forget to make sure you're still keeping your bacteria happy! If you have any questions for Sophie regarding any of the subjects discussed in this post or any other aspect of marine fishkeeping, she is more than happy for you to contact her via Twitter or email.