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Substrate, Filtering And BioFiltering

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So I think some info on this would be necessary before I start establishing my new tanks.


Sand - Can it house biofiltering bacteria? Can you use an undergravel filter? Is it better for plants? What type of sand is to be used for tropical aquariums and what fish can't have sand? Also.. Different types that can be used for freshwater fish?

Gravel - Houses biofiltering bacteria. Is this a better option if I wish to establish my 90L tanks? What fish CAN'T have gravel?

Soil - I've heard you can get soil for planted tanks? Is this useful at all? Obviously would not be used with an undergravel filter.. Also best to put gravel on top?

Other - What other types of substrate can you use and are they useful for cycled aquariums? (eg. riverstones.)

Colours - Brightly coloured fish prefer darker coloured substrate so they don't "feel" too conspicuous and it also provides a nice contrast to their colours.


Undergravel - Yes it may LOOK better, but is it particularly useful for cycling a tank? Are they efficient enough and how often do they need cleaning? (Considering they are mighty difficult to manouver once set)

Sponge - Unsightly sponge-on-the-end-of-a-tube in your aquarium that could be aesthetically unpleasant unless it was large tank and heavily planted/scaped. Can they be used for cycling a tank? Are they efficient? How often do they need cleaning? The filter pictured is a bio-sponge filter. They can also look similar to this

Submersible - I realise that sponge are essentially a submersible but they look/are rather different than what I wish to talk about here. They are particularly useful as you can attach spray bars and multi-directional flow to them with ease. (Spray bar pictured in photo) I understand you can use these for Mechanical and Chemical and sometimes Biological filtration but how efficient are they? And how often would you need to clean them?

Wet/Dry - Sometimes home-made and are usually used in the big filtration systems for Betta Barracks. Particularly useful for fish of the same species and Marine fish. The heater can also be placed in the sump of these filters. How efficient are they? Good for cycling? How often are do they need to be cleaned? Please realise that if you have seperate aquariums running off one wet/dry setup, you must have fish that require the same/similar water conditions! (eg. Not an aquarium that needs PH 6.4 and another than need 7.8)

Power - The hang-on-back filter. Can be used for cycling but are they efficient enough for larger tanks? These can easily be "jacked up" to create less flow and are, from what I understand, useful in oxygenating aquariums as the flow comes from above. How often should these be cleaned?

Canister - Virtually silent, powerful and can be easily hidden from view under the tank. These are generally expensive. Are these filters efficient for all types of freshwater tanks? I understand that not all can be used for cycling an aquarium.

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I am in the process of setting up a tank also. It will be fully planted and pretty much no-expense spared... The reason I am doing it the "expensive" way, is because my current 2ft has, over the years, chewed up easily as much as what I will be spending on the new one. The point being, it is best to buy the very best that you are able to afford, and not go ahead with this bit or that thing, "just for now". You will most certainly end up spending double what you have to.

Now, having said that, yes, SOME canister filters can be expensive, but if you want a nice display tank, with awesome filtration, they almost cannot be beaten. There are plenty of brands around that will do a perfectly fine job, for not too much outlay. Hang on filters are also good, and not overly conspicuous. These are always available very cheaply. Now, if you are not too concerned about appearence inside the tank, a sponge filter is a great, cheap way to bio-filter your tank. Easy to clean, as well. As to the others...a wet/dry is a great filtration system, but can be bulky and messy. Good for multiple tanks on the same system, though. Internal filters...well, they are just internal filters...they do the job well, but will never look attractive. UG filters are good, but very hard to keep clean...and very 20th Century, lol.

Substrate. Again, find the best you can afford. A gravel of about 2mm grain size is perfect for almost any application, whether planted or otherwise. Of the specialist planted substrates, you could try EcoComplete or Seachem Flourite. These are both around $50 a bag and a far cry from some of the ADA gear that is vastly overpriced in this country. You are right, bright colours are a no-no...not only does bright blue gravel look ridiculous, it does nothing for your fish. Everytime I see a tank with yellow/blue/green/anything but brown gravel, I seriously want to vomit...it just looks naff.

Now, the tank I mentioned setting up, is a long term process. I am buying things as I can afford them. I am not by any means rich, but by doing the research, I have came to a setup that will be exactly what I want in every way. Key point, be patient. Don't rush it. Do what you can, as you can and make sure it cycles properly...

Good luck!

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Ok here goes the thoughts of a madman.....


Sand - generally no good for biofiltering bacteria - can cause anaerobic bacteria which then release sulfurous gases (highly toxic) unless it is regularly groomed - can cause cloudiness to the water after this action. Sand can cause severe wear in filters with moving parts. Sand is also hard to 'vacuum' the debris from. Sand cannot be used in an under-gravel filter. Washed river sand is good for plants but some have successfully used 'play sand' and other bagged sands from major hardware retailers - depends on the effort you put into it as to how well sand works. Some fish will make a mess with sand - others love digging in it - best to work out what type of fish you want to keep and do some research first on what substrates they have in their natural environment.

Gravel - Most fish keepers use gravel - pebble size from 2mm up to 10mm again depending on fish and their habitats or habits. Eg: shell dwellers prefer sand to bury their shells in rather than heavy gravel (they are only tiny fish) but a large cichlid will move mountains of larger size gravel like a bulldozer but not do so well with sand.

Soil - Ghengis answered this one pretty well above. Commercial planted tank substrates can be pretty expensive - unless you're growing expensive plants I personally think plain old gravel is good enough to start with. Some of these substrates work better on their own, or with many additives (which also can be very expensive). Do a search on the forum to find some home recipes for planted tank substrates.

Other - no substrate is the easiest to clean!

Colours - dark substrates tend to bring out the colours of fish - white / light substrates can cause the fish to look washed out in colour at times. As Ghengis said - 'pretty' coloured gravels are for the 5 year olds with their first gold fish bowl! LOL


Undergravel - A well set up ug filter works very well - loss of power to the air pump though can cause disaster (lost a tank of angels overnight due to loss of power) as the bateria and gunk built up under them can be very toxic if it gets back above the gravel. Cleaning them usually means tearing down the entire tank to get them out. Some people do reverse ug filters - they use a powerhead to blow water under the plates and cause the water to come up through the gravel - good for biofiltration but no good for mechanical - they usually have another filter in the tank to take care of that.

Sponge - Cheapest and probably one of the most efficient biofiltration devices available. In the pic you referred to - the larger filter is rated for 480litres and the other is rated for 240litres. Easy to clean - squeeze it out in a bucket of tank water once a week. Can be hidden behind rocks or plants easily and only has one 4mm tube coming into the tank (which can be hidden easily too). Provides extra aeration to the tank. Cheap to run - can run many filters from one pump - I'm currently running about 20 tanks from one pump with the capacity to add another 20 if I want without having to buy another pump. Can be used to cycle a tank or keep a spare in a spare tank to kick off a new tank quickly.

Submersible - Large submersibles have good bio capacity but the smaller sized filters are really only a water mover when you look at the amount of bio material they contain. They are bulky and take up tank room and if you don't get the right capacity filter you either blow the scales off your fish or you underfilter the tank. Definitely not good for fish like bettas. Some of these chew a fair amount of power for the value they offer. I have two of these in a 4ft tank to give water flow but don't rely on them for mechanical of bio filtration alone. They need to be cleaned regularly - weekly or more often depending on how messy your fish are. To filter for bio, chemical and mechanical - you would need something the size of an Otto1200 (1200 l/hr flow) with three cups and even then you are only providing less than 1.5 litres of filter media.

Wet/Dry - Great for large tanks, marine setups, betta barracks, and tank systerms with fish all requiring the same parameters. Saves on heating costs. Exposes all tanks in the system to disease if one tank has a problem - all have a problem. Fairly expensive to drill all the tanks, plumb them and then fill a large sump with filter media and pumps. Easy to access and clean without disruption to the main tank. Some sump plumbing makes a fair bit of noise if the return pipes are not setup properly (nice to go to sleep with). Need to be maintained weekly or fortnightly depending on the fish and how messy they are or how much you overfeed...

Power - The hang-on-back filter. Some of the larger HOB filters can compete with canister filters and have capacity for various forms of filtration media. Generally low power usage and provide minimal extra aeration. Easy to access and clean with minimal or no disruption to the tank. Do not provide much in the way of water currents in a tank. If not cleaned regularly - filter material can become clogged up and the filter can overflow - either into the tank or onto your floor!

Canister - Virtually silent, powerful and can be easily hidden from view under the tank. These are generally expensive. Are these filters efficient for all types of freshwater tanks? So far - YES on all points raised. Expensive - yes - for Eheim or Fluval filters - prices can go up to $800 or more dollars - it pays to shop around for these items. There's a few LFS's in Brisbane that have excellent / competitive prices though. Canisters can be used when cycling an aquarium. They have lots of space for filter material - larger filters have up to 10 litres of space available (on average around 5 litres). Usually have media trays to separate and organise your filter media. Some have inbuilt UV sterilisers. The model number does not always indicate the actual flow rate in l/hr - read the specs carefully before buying. If you do not have the hoses attached properly it is possible to have them let go and siphon the entire contents of your tank onto your living room floor (I had 1½" of water left in my tank and a lot of unhappy fish that day!)

Whatever you do with filtration - it must match the fish and the environment you have in your tank. If you have a sand substrate you don't want 2000l/hr blowing round and giving you and aquatic sand storm. If you have an amazon biotype tank with leaves all over the bottom - same thing applies really. Choose the filter to suit and always make sure you turn over your water at least 4-6 times an hour - there is no such thing as over filtering!

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Thanks Lisa... was going to ask if you thought it worthwhile to pin... along with any other's thoughts on the topic too...

Do you think it would be better in another forum rather than gen discussion? Perhaps in the Equipment & DIY or the Aquatic Plants & Aquascaping forum?

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Yeah, fishy, that was a great response!! Pretty much everything I wanted to say, but just done much better (I blame the fact that I was typing at work and didn't want to get sprung, lol!)

I do want to reiterate, though, that not all canisters need cost over $500. I believe that alot of beginners are scared off by what they think they have to spend on such a device. Yes, the Fluvals and Eheims etc can get pretty pricey, and for good reason as they have a great reputation, but I have always been a fan of the Aqua One fiters (be they canister or otherwise). They are a fantastic brand, right across the board. I just the other day received my new Advance 1250, to go under my new setup. Cost me $165. Plus delivery. This will be the second Advance in my collection, the other being the 750 ($125) sitting under my 2ft. I honestly cannot recommend these filters enough...you simply cannot go wrong. Particularly with a 4 year warranty. This is not to say everyone should have one...an FX5 would be an awesome filter to own if that's what someone wanted and could afford, but it does mean there are options. Just don't try to go TOO cheap, lol.

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