HMF Mattenfilter - lots of pictures and FAQs

[J?rg]

You picked the one photo which shows, in my eyes, a too generous use of the filtermat. Usually, one tries to construct a quarter-circle, and the picture above looks more like an egg or ellipse. ;-)

I tried to do a calculation for some typical tank sizes, so you can see how much ground surface of a tank is used for a HMF (corner construction)

L W H are the lenght, width and height of the tank in [cm]
Area [cm2] is the surface area of the tank
Area HMF [cm2] classical construction : The recommended size of the mat according to calculations for HMF where the mat is a the left/right end of the tank, stretching from front to back.
radius mat [cm], the recommended radius for the mat, if built in a cornered way
area bent mat [cm2]: the surface area of the mat if constructed that way and stretching from ground to water surface. VERY close to the results two colums left
space req, for HMF [cm2]: how much area is used for the tank, when seen from above,
% of total space: how much of the total surface area of the tank is used by the tank


Interpretation:

In small tanks (like the 63 liters =17USG) a HMF in the cornered construction uses 1,1 % of the bottom area of this tank. This percentage increases with tank size.


What to learn of it: In small tanks you will have to build your HMF with a larger radius, otherwise a 5cm radius is too small to place a pump/heater behind and such a small radius bends the mat too much. In larger tanks (> 80Gals) it is recommendable to build two in each corner, preventing an all too large filter in one corner.


The area behind the mat: It's used usually for the heaters, the CO2 reactor, the pH-electrodes, a bag of peat for watertreatment. Usually no extra filtermaterial.

When you want to do you own calculations you will need the formula for the circumference and the area of a circle.


Hope that helps.

Jörg

 

[J double R]

any reason why, in a very tall or large tank, that you couldnt use two pumps and two outputs if you wanted to keep it to one corner?

 

[J?rg]

No, that's actually the setup i use in a 300 liter tank, a HMF in one corner, radius = 16cm (thats the 2nd tank in the example above) and two pumps (1 with 300liters/h , a 2nd with 350 l/h). one output goes diagonally, the other on the long side of the tank. But for optical reasons >>I<< would do it with two HMFs in >>that<< specific tank. Then there's the Dupla CO2 reactor in the filter chamber and no more space left.

Another reason for taking two pumps was a additional backup if one fails. And 300 liter/hr pumps are the most widely sold, hence 2 are cheaper than 1 with 600 ltr/hr. You have a wide range of products to choose from, any large manufacturer has them, like the Eheim compact series. (I like Eheim, i just don't need their canisters anymore!)


Jörg

 

[wolf13]

Now thats an interesting setup, I might give that a try on one of the tanks i am setting up. Any of you US guys know where to get the padding?

 

[J double R]

seems like you could use any sort of filter padding, just try to find one with dimensions bigger than what you need and cut it down....

 

[J?rg]

this is where a German living in the US ordered his material:

http://www.foamandupholstery.com/out_door_foam.htm

scroll down to Regicell foam. Seems that it works.

 

[BoCoMo]

This deserves a trip ttt!




(if for no other reason than because of this tank - how cool!)