Filtration rates, flow, and other questions

Ill try to find the chart, and come back to you. From what i gathered is that Jebo and Lifetech pumps are the same thing? My pump model is exactly the same is this one http://www.jeboaquarium.com/Water%20Pump.htm and it also looks the same with the same specifications. the max output is 2500l/h and the max head is 2.5 m. but i cant seem to find a chart

 

Hi Ashley and the rest of you guys,

Apologies for not replying earlier, I have only been answering crisis type requests of late because I am preparing a massive research application which I need to submit on Monday.

A lot of what everyone has contributed is correct and I agree with it, but I want to add a few things.

When considering the efficiency of a filter, we must just pause for a moment to think about what it is supposed to do.

Firstly, we all want the filter to remove suspended material to ensure that the water is clear, in other words, mechanical filtration.

Secondly, we want the filter to convert the ammonia (NH4+) produced by the fishes to nitrite (NO2=) and then to convert the nitrite to nitrate (NO3=). Fishes are very sensitive to ammonia and nitrite and are less sensitive to nitrate, but this depends on the type of fishes that you keep. Also the conversion requires oxygen and the water that goes through the filter must carry the oxygen if this is a canister filter and in a sump can be added by aeration.

Thirdly, we may want the filter to convert nitrate to nitrogen and oxygen gas by means of the process called anaerobic filtration.

Most aquarists aim that the filter does the first two things, and only the real specialists aim to get the filter to do the third.

So first and foremost, the filter must do the ammonia to nitrate conversion. How, we need sufficient medium for the Nitrosomonas and Nitrobacter bacteria to grow on. They prefer a solid medium such as ceramic rings and not plastic such as bioballs as already indicated by some of you. If the filter does this conversion properly and efficiently it will means that you cannot measure ammonia or nitrite levels in your aquarium. So, as long as you cannot measure ammonia and nitrite in your filter, your filter is in order and meets your requirements, it does not matter if it is a canister or a trickle filter, the flow rate does not matter, that is the bottom line.

Now, when does this change? Well, if your filter gets clogged with suspended material, the flow rate will drop and the oxygen going through the filter will drop. This is changed more easily in a canister filter because the surface area of the filter is smaller, what I actually mean is the bore of the filter, the width of the baskets that carry the media. In a sump, this can be made much larger and depends on the size of the chambers. However, if you have a whole lot of up and downs, it is the bore, or the surface area of the single cell that decides the efficieny of the filter, if you make these chambers larger then the bore is larger. Now if the flow rate drops due to mechanical blockage, the amount of oxygen also drops and the filter cannot do the ammonia to nitrate conversion that well any more. How do we know this? If you would measure ammonia and nitrite levels you would see that these would go up. In a sump, because of the size of the chambers and because oxygen can be introduced into the filter after the water has flowed into the filter using an airstone say, the oxygen levels can be kept higher more easily and therefore the sump type filter generally has a higher rate of being able to perform this conversion of ammonia to nitrite or biological filtration as we call it. However, if you do not allow your canister filter to get blocked due to suspended material, there is no reason why it should not be completely adequate for your circumstances.

The third type of filtration, the anearobic filtration, can only take place in areas of the filter that do not contain oxygen. In a canister filter that flows at a high rate it is hardly possible to have any area in which anaerobic filtration can occur. Aerobic bacteria compete with anaerobic bacteria and are able to grow much more easily, so in realistic terms a canister filter will not have any anaerobic filtration. Then at the flow rates that are normally used in sump filters they will also not really allow anaerobic filtration to occur either. It is only if you have a closed canister type filter through which you allow water to circulate very slowly that you will get anaerobic filtration.

So, the whole filtration issue boils down to filter maintenance (regular cleaning or it will not work) and filter design (large surface area and large bore).

What influences this:

Stocking rate and feeding: high stocking rate and high feeding means high ammonia production and means you need more filtration.

Nitrate production and removal: if you want to regulate nitrate levels, you can do so by water changes, or by having an anaerobic filter linked to your system (see explanation above), or by having many plants under high lighting and with CO2 fertilization. So you can see that a number of factors will influence nitrate levels in an aquarium.

Where can things go wrong? IF YOU ARE KEEPING DISCUS! (as always, problems with these damn fishes!) Discus are far more sensitive to ammonia and nitrite than other fishes are. So, even if your kits are measuring no measurable ammonia and nitrite, you have a problem if your filter is even only slightly clogged with muck, and the nitrite levels are ever so slightly elevated. Keep discus for a week under such circumstances and you will start loosing some, they go dark immediately, stop eating and then develop one problem after the next. Goldfishes or Malawis would be perfectly healthy under such conditions, whilst your discus would die. In keeping discus, another complication is of course the high temps at which you have to keep them, because at 28 C+ the solubility of oxygen in the water also drops dramatically, so temp also has a influence on filtration.

So, it is complicated and filtration very definitely depends on your fishes and your stocking rate and a general guideline is actually difficult to give, but monitoring of ammonia and nitrite levels is good to help you. I can by now smell an aquarium and tell you if you have nitrite problems, I have a very sensitive nose and somehow increased nitrite causes bacteria to multiply which I can then smell from experience. What I have also found is if you take the filter medium out of a canister filter and it is slimy if pressed between the fingers, this is the result of inadequate filtration and therefore increased indicate increased nitrite levels.

Kind regards,

Dirk

 

copy and paste and save in file of very important things...

thank you very much for taking the time out to explain in detail(all posts), i have been keeping fish for about a year and have a 600l and 1000l imabout to set up, am totallly inspired and encouraged by the quality of advise and guidance here...will use advise!!!

erm prof about that nose....hehehe my elder always impresses upon me how valuable experience is...you know cellular over cognitive, it can only be love that has driven you that far...bless you

Fire!

 

Prof thanks for the reply, i think that makes things alot clearer for alot of us

 

Hey thanks prof. Now i understand filtration a whole lot better. and i dont need to worry about my pump anymore

 

Hi Prof , I recently read a book published in the early 90's and the writer was talking about an anion exchanger in wich exchanger resin was used as filter material and wich removes nitrate from the water . Do people still use these filters and if not why not .Thanks

 

Hi Farmer,

You are correct that one can use an anion exchanger resin to remove nitrate but then this sort of system can hardly be called a filter, this would be called an anion-exchanger column or something. However, if we leave the names aside this sort of material can be packed into something similar to a canister filter and it will remove the nitrate, but as the name indicates this is an exchanger and not a remover, it exchanges nitrate for chloride (not chlorine, be careful) ions, Cl-, and these are then effectively added to the water. So this filter may remove the nitrate but it does not soften the water really which is one of the reasons why they are not often used any more. The other reason why they are not used is because they require regeneration, in other words they have a certain capacity for nitrate and once that has been reached then they do not remove nitrate any more, after which one then has to pour concentrated salt solution through the filter after which you need to wash it with distilled water to wash away the excess salt. This is labout intensive and messy which is another reason why it is not used any more. One of the biggest reasons why these anion exchangers are however not used any more is because they also remove humic acids, the brown pigments in water coming from wood and plant material, and these are actually beneficial for fishes such as discus, so this sort of filtration actually also has a negative side to it.

Modern discus keepers have just opted for frequent water changes to reduce nitrate levels which is easier and at the same time softens the water, in other reduces the total amount of dissolved substances in the water.

Hope this clarifies the matter.

Kind regards,

Dirk

 

Thanks very much , it sounded too easy to be true .

 

Hi Guys,

There is one additional aspect that I do want to mention and that is about flow rate. Flow rate can have a big influence on biological filtration in that the flow rate has an effect on how fast ammonia and nitrite are removed from the aquarium or whether the levels are able to rise. Basically the filter is constantly diluting or reducing the ammonia and nitrite levels and with a good filter that has a high flow rate one strives to reduce these levels to below where they are dangerous for the fishes. Even with a flow rate of half the aquarium volume per hour, you would achieve this is most aquaria, but again with discus keeping this can be a problem. Firstly, discus are large and need to be fed a lot which means that they will produce a lot of ammonia which will be converted to nitrite in the filter and then to nitrate. If the flow rate is not high enough, and one should aim for 1 x tank volume per hour to 1 1/2 x tank volume per hour when keeping discus, the ammonia and nitrite levels, normally it is only nitrite levels, creep up ever so slightly. When tested with a nitrite test kit the levels appear to be normal, but discus are so sensitive to nitrite, that they then show symptoms of nitrite toxicity and stress. They would go dark and would breathe fast. Why? Because nitrite is taken up by the blood where it oxidizes hemoglobin, the pigment in red blood cells that carries the oxygen, to methemoglobin, which cannot carry the oxygen. So nitrite toxicity actually leads to asphyxiation, or shortage of oxygen, in fishes that suffer from nitrite toxicity. You can reduce this by water changes and you can add salt to help the fishes temporarily but really what is needed is stronger filtration. What again makes matters worse is that when keeping discus you also need high temperatures which cause less oxygen to be dissolved in the water, so again the fishes would be getting less oxygen and this can make things worse.

So, once again, filtration and filtration rate in discus keeping is far more critical than in an aquarium in which other fishes are kept.

Kind regards,

Dirk

 

@Dirk Bellstedt

Now you have thrown my logic way out of sync here, and I'm going to try and ask for clarification in the above post.

From what I understand, you are saying that if I have a 300litre tank, with normal plant, and a good stocked (not over stocked, or stocked to capacity) fish tank with fish like tetra's, dwarfs, Guppies, (i.e the basic starter point), a filter rated a 150litres per hour would be suitable?? This is a basic fundamental point in all fish keeping. Here on TASA we have been advising new member to aim for 5X turn over per hour. Meaning if it's a 300 litre tank, they should strive for 1500l/hour tank.
And then onto the bigger fish, Discus for example: If I had a 300litre tank, stocked correctly with discus, and obviously maintained correctly, you are saying that a 450l/h filter will suffice?

Obviously we are in agreement here that the correct water changes are being done, and that suitable filter media is inside the filter to carry out the biological filtration.

 

@Dirk Bellstedt

Now you have thrown my logic way out of sync here, and I'm going to try and ask for clarification in the above post.

From what I understand, you are saying that if I have a 300litre tank, with normal plant, and a good stocked (not over stocked, or stocked to capacity) fish tank with fish like tetra's, dwarfs, Guppies, (i.e the basic starter point), a filter rated a 150litres per hour would be suitable?? This is a basic fundamental point in all fish keeping. Here on TASA we have been advising new member to aim for 5X turn over per hour. Meaning if it's a 300 litre tank, they should strive for 1500l/hour tank.
And then onto the bigger fish, Discus for example: If I had a 300litre tank, stocked correctly with discus, and obviously maintained correctly, you are saying that a 450l/h filter will suffice?

Obviously we are in agreement here that the correct water changes are being done, and that suitable filter media is inside the filter to carry out the biological filtration.

 

Thanks Professor!

So, are we saying that faster is always better? And if not, what can be considered at too fast? I have a 300l tank and filtering at around 2000 l/h.

 

Hi Ashley,

I think we may be misunderstanding each other here. You are correct and so am I, but we are talking about different types of filters here. If you have a canister filter, which is the type of filter that is, I guess, most often referred to here, you have a problem with filter medium capacity and the total amount of bacteria that can occupy the filter media is actually small. The only way in which you can get the ammonia and nitrite levels down then, is to filter the water over the medium many times in an hour, this is similar to what I replied in my first post. What happens is that even if you were to filter the volume of the tank over such a canister filter once in an hour, it would just simply not get the nitrite levels down enough, and so you have to filter the water over the medium more often per hour. This is the basic point that you are making and this is correct.

However, if you can a high capacity trickle filter, that removes the nitrite down to almost zero during the 1 to 1.5 times the aquarium capacity that the water runs over the filter in an hour, then this is enough! My comments were referring to such a setup, but then very few people have such a filter as it takes a lot of space and it needs to be properly designed to contain medium that is actually active, by that I mean filter medium such as gravel or ceramic rings, and that it is strongly oxygenated and therefore occupied by active bacteria doing the nitrite breakdown.

I have too little time right now to do some measurements, but I will see if I can actually measure my flow rate through my discus tanks that have a huge trickle filter, but I am absolutely sure that I do not circulate the water 5 x per hour, but my discus are not only very healthy but also breed in this system.

I will get back to you on this matter.

Kind regards,

Dirk

 

Hi Shibby,

your post came in whilst I was writing. No, if you read carefully, I am not saying the faster the better, as a matter of fact fishes like discus do not like a high current caused by higher flow rates. The crux of the matter is the volume of the filter medium, it needs to have a high enough volume so that there is enough place for the bacteria to occupy and do the biological filtration.

Kind regards,

Dirk

 

Hi Ashley,

I have now gone back to my recirculating discus system and made some flow measurements. The total tank volumes are 1200 litres and the total flow over these tanks is 1400 l per hour, in other words a little over 1 times per hour. I specifically measured one tank of which the volume is 300 litres and the flow rate was 320 litres per hour.

My biological filter is a trickle filter, consists of a course gravel filled aqaurium and the dimensions of the chambers which are filled with gravel are 1.2 m x 30 cm x 20 cm, in other words 72 litres. Before the water is filtered over this filter it is strongly aerated. Water is jetted onto this filter medium and the gravel is not submerged. The flow rate over this bed is 1500 litres per hour! So you can see that this is one mother of a filter in comparison to a canister filter. If you were to run a canister filter your filter medium capacity will obviously be much less and to compensate for this you would have to increase flow rates.

So, where does this bring us? I think that this actually illustrates very nicely how important the biological filter capacity of a filter is, and what the implications of a filter can be. I smaller filter medium capacity canister filter needs greater flow rates and a large trickle filter system can work with a much slower flow rate!

Kind regards,

Dirk

 

That's exactly the type of answers I wanted to know @Dirk Bellstedt.

So I can therefore conclude that the more filter medium you have, and places effectively, you could slow down the filtration FLOW rate... but the less medium you have, the more rate you would need. Makes a lot of sense.

So in essence, a person running a sump could be turning over less water per hour than a person running an internal, or HOB filter... and the filtration would be pretty much the same.

 

...AND a person with a small sump like myself can, in the event that no fish require slow moving water, speed up the filter process rather than getting a bigger sump and still have the filter benefits.

 

Well obviously because your sump is small, you have far less filter medium in there... hence the need for higher flow rate.

Light bulb moment- "The volume of filter media in your filter will determine the required flowrate."

 

There would of course have to be a constraint on this light bulb moment where the flow rate exceeds the filtration capabilities, ie; using 1 ceramic ring and having a flow rate of 1000 X your tank volume in an hour. It just is not going to work.

 

Yes all extremities should be avoided as always...

But its safe to say that for a somewhat constant filter quality, the flow rate is inversely proportional to the amount of filter media available.