Tropical fish filtration

Hi there, I'm a long time fish keeper but haven't kept tropical fish for 20 years. Back in the day I used a Fluval external filter: sponge > carbon > ceramic rings (mechanical > chemical> biological).

So it's been a long time and thoughts of the best tropical fish filter media may have changed some. What is the best method now? Does anyone still use mechanical filtration and do you vary the sponge types (course > medium > fine)? Does carbon still have a place in modern tropical fish filters? I'm certainly planning on using it while I cycle and if I ever have any water quality crisis or need to remove meds. And bio media, there seems to be new stuff like bio-home which looks interesting. I quickly picked up some ceramic rings off eBay but am now wondering if they are any good or should I swap them out for a better option.

I'm happy to read over any links or old posts on the matter as I'm in need of a general education, but as I have the basics (if a bit outdated), I would appreciate some insights from you guys on my specific questions.

To be quite honest, there has not been any major changes since I started keeping fish 40 years ago.
The principles are the same; it is just that various media may have been "perfected" a little or made more widely available at lower cost, and there have been more molecular sieves made available off-the-shelf.
Ditto the same with filters, but power filters have been made more powerful and cheaper and maybe bigger and probably do not leak as much

All in all, choice has got bigger. But it is still much of a muchness.
There is nothing wrong with sponges, filter floss, activated carbon, or ceramic rings so long as they are used correctly.

ian

Thanks Ian, yes I suppose nothing radical has changed. There's a couple of clarifications I'd still be interested in hearing more about:

When using mechanical filtration and do you vary the sponge types (course > medium > fine)? Last night I found a set of sponges on eBay intended for pond filters. I intend to throw out my useless AquaOne cartridges and use this, optional carbon, and bio media.

I'm curious if anyone has used the bio-home. The idea that anaerobic bacteria takes hold in the middle of the porous media which gives you better nitrate removal makes sense. Whereas my ceramic rings would hold ammonia and nitrite processing aerobic bacteria. I'd like to hear thoughts about this.

The bacteria that remove nitrate in anaerobic conditions are aerobic bacteria. and any media can hold them if the media is anaerobic (it depends on how the media is used or placed).

Although there are many ways removing nitrogenous waste almost completely from a tank via filtrations system/biological actions, water changes are the best method as the water changes remove compounds that filtration will not remove.
Water changes also replenish the "life" (RedOx) of the water in an enclosed system.

ian

I'm pretty sure the bacteria that convert nitrate to nitrogen are anaerobic. I don't think ceramic rings would offer the same potential for anaerobic bacteria.

newkie wrote:

I'm pretty sure the bacteria that convert nitrate to nitrogen are anaerobic. I don't think ceramic rings would offer the same potential for anaerobic bacteria.

Nope. The denitrifying bacteria are aerobic, not anaerobic.
Bacteria that convert ammonia to nitrogen gas are anaerobic though.

Normally, ceramic rings are used in a manner that would not offer much in the way of anaerobic conditions, but that is more to do with the fact that close-packing is difficult. But if they were positioned in a way to receive anoxic water then they would also enable anaerobic reactions to occur.

ian

Again I'm talking nitrate -> nitrogen. For example in a reef tank a deep sand bed offers the anaerobic conditions to naturally convert nitrate to nitrogen and you'll see little bubbles of nitrogen develop in the sand bed and bubble up.

The removal of nitrates from sea water is accomplished via uptake by algae or by anaerobic bacterial reduction of the nitrate to nitrogen gas. Under anaerobic conditions, bacteria such as Pseudomonas, Micrococcus, and Paracoccus convert nitrates to nitrogen gas, in a process called denitrification. These bacteria are facultative anaerobes, and can grow in the sand, where water flow is minimal and oxygen levels are low. They participate in the removal of nitrogen from the aquarium system, because the gases they produce from nitrate reduction escape to the atmosphere.

newkie wrote:

Again I'm talking nitrate -> nitrogen. For example in a reef tank a deep sand bed offers the anaerobic conditions to naturally convert nitrate to nitrogen and you'll see little bubbles of nitrogen develop in the sand bed and bubble up.

The removal of nitrates from sea water is accomplished via uptake by algae or by anaerobic bacterial reduction of the nitrate to nitrogen gas. Under anaerobic conditions, bacteria such as Pseudomonas, Micrococcus, and Paracoccus convert nitrates to nitrogen gas, in a process called denitrification. These bacteria are facultative anaerobes, and can grow in the sand, where water flow is minimal and oxygen levels are low. They participate in the removal of nitrogen from the aquarium system, because the gases they produce from nitrate reduction escape to the atmosphere.

They bacteria that convert nitrate to nitrogen gas (denitrification) are profoundly aerobic bacteria (I can't think of any anaerobic ones). Under low oxygen conditions, the bacteria will reduce nitrate to form nitrogen gas (much like we reduce oxygen in aerobic conditions to produce water during respiration).

ian

Yay! We eventually found the same page.

Yeah you can see in this link it says they can also grow in aerobic conditions but when thinking about DSBs and nitrate->nitrogen gas anaerobic conditions is mentioned more.



Anyway... this is why I find the bio-home media appealing and was looking for reviews on it. Just looking at it you can imagine it would be a good host providing lots of surface area and both aerobic (outer pores) and anaerobic (in the core) conditions.

I worked on developing the dentrification systems for fish keeping (mainly for marine in public aquaria) many many years ago
On fish keeping sites I do lament that so much "new stuff" is actually very archaic.

Anyway, I have not used or tested that product.

Different media would have differing ability to allow the bacteria to "cling" to it, I'm not totally convinced that that is a useful determining factor for fish keeping so long as some form of colonisation is allowed.

There is always a major danger in forcing an anaerobic system within the fish tank....that is one of making sure that anaerobic bacteria (particularly sulphur reducing bacteria) do not out compete the aerobic bacteria within the anaerobic environment.
If hydrogen sulphide is produced then not only is that toxic within itself but it can act as a catalyst for alternative pathways within the nitrogen cycle to convert nitrates to ammonia.

ian

bio-home works well, never had any problems with it. Didnt seem to clog, which is good. Never used the bigger ones, only the standard. I prefer media a little smaller in size, but thats a personal thing.