How Do Designers Choose Filter Media Sequence?

[waterdrop]

I got to thinking about the tradeoffs involved in what sequence of media the water passes through in an aquarium filter. To my rather inexperienced eye, there are various subtle tradeoffs and I was wondering what others think.

For instance, one bit of advice I've gleaned is that some type of fine-pored material, like poly or a fine sponge, can be used to stop the debris early and allow the larger media that follow a longer time between cleanings. In contrast to that, there also seems to be some sense in a material with larger pores being at the front to stop big particles without causing an overall blockage early in the maintenance interval. These contrasting goals seem at odds with each other.

Another interesting subtle contrast is that between ceramic rings (noodles) vs. ceramic beads. Both of these materials are often made with a ceramic or sintered glass I believe which is designed to have many surface openings with spa (ce for bacteria to attach to as possible. But the rings, being heavy and solid, making them relatively non-movable by the filter water flow, are able to redirect the water flow in random ways without "paths of least resistance" being developed as can happen in a sponge. Ceramic beads, in contrast to rings, can have even more surface area, although are somewhat more prone to paths of least resistance.

So it seems like the designer has at least three goals; ideal bacterial surface area (max area and quality (bio-filter)), ideal mechanical filtering (stoppage of debris of all sizes) and retention of rated water flow.

What do others think? Are there other goals for the filter media itself? Are there other trade-offs concerning placement sequence or material choice? (realize I'm sort of ignoring chemical filtration, like carbon or specialized chems but I was trying to stick to basic normal operation). I think the fine-tuning of media in the filter is one of the skills or black-arts that very experienced TFF members are often good at, but is difficult for beginners to understand/learn!

~~waterdrop~~
ps. sorry! I need to learn to write one-liners. But I'd really enjoy hearing your thoughts!!

 

[andywg]

For me the most important thing is to get all the mechanical filtration done before the biological. I can never understand people putting filter floss after the biological media to "polish" the water. All they are doing is allowing phyiscal waste to flow into the bacterial chamber and clog up the high surface area.

So I would alway divide my filtration into two very seperate parts: mechanical and biological.

First up, I should point out that all my FW tanks run on a trickle tower wet/dry sump system (SW is another are altogether!) and that therefore I am not likely to be among the majority of fishkeepers with my filtration style. The water flows out of a pipe onto the mechanical media. After flowing through the media the water goes through a drip tray into a tower filled with bioballs for mechanical media and lands in the sump to be pumped back and the cycle goes on.

With regards to putting larger media first in mechanical, that is a function of how often you want to clean the media. I used to have filter floss on top of my drip trays and it did a great job, but it also needed cleaning about every 2-3 days if I was to keep it really clean (which is partly evidence of my stocking levels, and partly evidence of how superior this style of mechanical filtration is over submerged media). I now use a fine sponge with a coarser sponge on top and this does well for me.

I then have my towers with the bioballs; high surface area:volume ratio which I like. I have not had to clean out the towers in the close to 3 years or more that the towers have been going. By putting a decent mechanical filtration system in that gets done at (almost) every water change I have kept clogging down to a bare minimum.

 

[Miss Wiggle]

can't offer all that much but here's what i do

sponge first - catch most of the debris
then some bio media such as bio balls and ceramics
then a bit of floss at the top to catch any last bits of mank that didn't get caught by the sponge or were built up in the bio media.

 

[rabbut]

My ordering is Corse sponge to catch large particulate waste, then medium to stop anything that little be smaller, then a fine sponge for those little bits of particulate waste that wern't caught by the other foams. Next it goes through carbon (where appropriate, very rarely used type of thing) then floss to polish. Bio-ceramic media is in my last compartment. This system is designed to not clogg quickly, and the sponge obviously acts as a bio-filter if left long enough. Never cleaned the ceramic, and the sponge only "needs" doing every few months, but could easily go a year without being cleaned by my reconing. I am keeping fish that don't like desolved organics though, so like to keep my mechanical filters on the clean site of things.

HTH
Rabbut

 

[MermaidMel]

For me the most important thing is to get all the mechanical filtration done before the biological. I can never understand people putting filter floss after the biological media to "polish" the water. All they are doing is allowing phyiscal waste to flow into the bacterial chamber and clog up the high surface area.

So I would alway divide my filtration into two very seperate parts: mechanical and biological.

First up, I should point out that all my FW tanks run on a trickle tower wet/dry sump system (SW is another are altogether!) and that therefore I am not likely to be among the majority of fishkeepers with my filtration style. The water flows out of a pipe onto the mechanical media. After flowing through the media the water goes through a drip tray into a tower filled with bioballs for mechanical media and lands in the sump to be pumped back and the cycle goes on.

With regards to putting larger media first in mechanical, that is a function of how often you want to clean the media. I used to have filter floss on top of my drip trays and it did a great job, but it also needed cleaning about every 2-3 days if I was to keep it really clean (which is partly evidence of my stocking levels, and partly evidence of how superior this style of mechanical filtration is over submerged media). I now use a fine sponge with a coarser sponge on top and this does well for me.

I then have my towers with the bioballs; high surface area:volume ratio which I like. I have not had to clean out the towers in the close to 3 years or more that the towers have been going. By putting a decent mechanical filtration system in that gets done at (almost) every water change I have kept clogging down to a bare minimum.

o/t but your flipping avatar mesmerises me lol

 

[waterdrop]

Very interesting!

I think there is an important take-home message in these posts that its important to think about getting the mechanical part done before the bio part. Good for beginners (or guys like me who didn't truly know it well the first time around!) to try to understand when making changes to their media.

These posts do seem to support the idea of coarser sponge before finer sponge for the mechanical part, assuming one does not want to be forced to clean excessively often.

~~waterdrop~~