Let's talk the little-known built-in biomedia of a tank

[MultipleTankSyndrome]

The thread on pool filter sand inspired me to make a thread on this. I'd like to go over the obvious, yet often overlooked, built-in biomedia of the average tank, and why having separate mechanical/biomedia in your filter that you do and don't rinse, respectively, is not such a big deal.

Let's begin with the fact that biomedia is just providing a space for beneficial bacteria to live on. This is exactly what decor, substrate, live or fake plants, etc provide, and is also the source of the wisdom to use these from an established tank for jumpstarting a new tank's cycle/not removing too many at once from an established tank when changing them.
In fact, in the average tank, the surface area these provide for the bacteria far, far, far outweighs the surface area of the filter media. My favorite example of this is one of my 473 liter tanks, which is currently only filtered by an Aquaclear 75 with 4 sponges and a prefilter.


As you can see, those sponges and prefilter have nothing on the surface area provided by all the log/temple caves, grains of pool filter sand, fake plant leaves, and rocks. In fact, since that photo I have added 5 more rocks, a small piece of driftwood, and a small cave.
Therefore, they provide the most biofiltration in the tank despite being 'built-in' aspects not specifically designated for that.

Which brings me to my next point. Because of all that biomedia, designating some in your filter that you never or hardly ever rinse is no longer a concern.
This is my favorite thing about the built-in biomedia because I can easily rinse out everywhere in my filter that collects gunk 3 times a week, without ever having to worry about damaging the beneficial bacteria.

One final benefit that slips the mind of just about everyone, myself included until recently, is that so much in-tank biomedia makes a filter breakdown very non-disastrous if there is a manner to keep the water in the tank oxygenated (such as with Sicce pumps). All that must be done in such a scenario is to put the filter media into the tank (rinse if dirty) and keep it well oxygenated while the filter is being fixed or replaced.
The thing that got me thinking about this is my Aquaclear recently making unusual noises, making me suspect it might break and require me to use its warranty to get it fixed or get a new one.

In fact, this last benefit means that technically, you could run the tank with no filter at all once it has a good enough beneficial bacteria colony established plus a source of sufficient oxygenation! I would still run filters given the choice so that detritus can be gathered in a place where it's easy to access and clean out, but if the Aquaclear has to be fixed and I have to go filterless, I have no doubt everything would be fine.

[NancyD]

Well, I agree up to a point. Your tank will only grow enough beneficial nitrifying bacteria to deal with the bioload from a given amout of fish & food. If you suddenly remove a filter's amount of BB there will be a "lag time" until it can grow enough to compensate. Theoretically it can double in 24 hours...but how does that account for all the surface area of the filter media & the oxygenation it provides by water flow? Yes, I know you change a lot of water often...& I'm sure that helps. I only do that much in quarantine tanks or if treating for a disease, not all the time.

I use 2 filters on most tanks, live plants & a lot more decor than you have. I like extra safety & not testing much. The bb only penetrate the top part of substrate surface area. I'm quite "safe" to thoughly clean 1 filter (it doesn't kill all the bb) or remove it or its media to seed a new tank. I'd lose 1/3-1/4 of bb (at very most) & live plants take up any ammonia etc until bb catch up. Unless you test very often you can't really know what's happened to your particular tank. Your powerhead will help with oxygenation but not all the surfaces a filter's media offers.

Yes, you can run a tank without any filtration, look up the "Diana Walstad method". Heavily planted & very light stocked, it can work...but not how most of us like to keep our tanks. Your idea is too broad for, lets call them our "regular" tanks. I'm pretty sure we've discussed all this before...

I'm also wondering how you fit 4 sponges in an AC 70, 3 is the most I can do with no other media. What's the trick? I'm always ready to learn something new, lol

[MultipleTankSyndrome]

You are absolutely correct. Both on the total amount of beneficial bacteria only being enough for however many fish+feedings there are, as well as the doubling being a very general formula that doesn't necessarily account for all affecting factors.
The thing is, given a well oxygenated tank, there ought to be equivalent (or at least nearly so) amounts of nitrifying bacteria per any surface area compared to the filter media, which was kind of the original point - that the sheer surface area of decor etc in well oxygenated tanks will end up having far more surface area than the filter media in the average tank, and more bacteria as a result.

Concerning all the water replacements I like to do, you might find helpful to know that pretty much all non-swamp fish come from water in the wild with 0-5 mg/l NO3, and this low to nonexistent NO3 also indicates low to nonexistent levels of the 'other' substances NO3 buildup indicates, like hormones, bacteria, dissolved organic compounds, etc.
Therefore it's advisable to have multiple weekly water replacements totalling over 100% of the tank volume to keep it that low as part of normal maintenance for any tank, it helps the fish health greatly in addition to helping this matter like you mentioned. I have word on this from Duane Stuerner, a retired microbiologist who has kept fish for over 50 years.

Yes, I have heard of the Walstad method - suppose I should have specified I meant without live plants, since live plants is the go-to thought for most when it comes to no filtration, not no filter or plants.
Besides it not being the go to for most fishkeepers as you mentioned, a big caveat many overlook is that 50% of the time (night), all the plants compared to the fish will effectively 'overstock' the tank with regards to oxygen, unless the fish are air breathers like Siamese fighting fish, snakeheads, walking catfish, common pleco, etc. So it's highly advisable to stick to air breathing fish.

Nitrifying bacteria can penetrate substrate all the way down if the circulation is sufficient (such as with sand sifting or digging fish). For how far it does in a given tank, a good way to know is to check underneath the tank for any black or gray areas - if there are any, they are are anaerobic areas where denitrifying bacteria instead of nitrifying bacteria live.
But if there aren't, there's a good chance every grain of sand has some nitrifying bacteria on it, as the sand will be circulated enough to avoid those anaerobic areas (although, anaerobic areas are desired by some fishkeepers to reduce the NO3). Presently I have no black or gray areas likely thanks to the pictus catfish and kuhli loaches, but I had some before the fish went in the tank because the sand just sat in the tank with no filters etc to let the silt settle before moving over the fish.

And you're absolutely right: as much as powerheads oxygenate water, they don't help with surface area for bacteria much. My point was that they provide enough oxygen to tank water for the built in surface areas to be good for bacteria.

By the way, I do have a story to tell that's a scary coincidence! Just on Thursday I fed the tank in question, and as usual turned off the filter before feeding so the food wouldn't get sucked up before it was eaten.
I forgot to turn it back on though, and then headed out for 8 hours. Seeing that this was the case when I got back, I got scared and tested for NH3/NO2 with both being 0 - given that the filter media would have had such a small portion of bacteria compared to the rest of the tank, it's easy to see how catching up for the rest of the bacteria on the decor, substrate, etc to deal with excess NH3/NO2 would be.

Unfortunately, you're probably right that my idea is too broad for 'regular' tanks. It was aimed more at a loachkeeper audience.
Most 'regular' tanks lack anything beyond the filtration for surface agitation, powerheads or flow pumps that would oxygenate the water in loachkeeper tanks are very uncommon in these tanks. Therefore the filter's water has the most oxygen, which is not just detrimental to the beneficial bacteria outside of the filter but can be to the fish as well.

We definitely have not discussed this before, but from searching Loaches Online as much as I have, lots of similar threads in which you and other older members like Emma, Martin, bookpage, newshound, etc commented on exist, so I can see why you might think so. And I can also see why so many threads exist, it's an important topic to discuss.

As for the Aquaclear 70 sponges, I must admit they are pretty maimed, falling apart, and worn down at the moment to be on the verge of replacement (on Black Friday). They currently fit much better than they did when new, when the available space was more like 3 1/2 sponges (you can even see the 4th sponge about halfway out of the water in the full tank shot, that was taken when they were new lol).
For that reason, though, I would not consider them the best option for mechanical media. They're far from the worst, but because they're also not the finest the maiming and fall apart from the necessary 3x a week filter cleanings begins after 2 to 2 1/2 months, which causes sponge pieces to go everywhere into the tank and also reduces the ability to catch/hold onto detritus between filter cleanings. I'd use Poret foam or appropriately sized, new kitchen sponges - being much finer makes them stronger and better able to catch debris, and although I won't have used either until Black Friday, I've been told by those who have that they last for years and years.

[MultipleTankSyndrome]

Using the best aquarium filter media will ensure that your aquarium will always be clean. The filter media is responsible for catching most, if not all, of the solid waste suspended in the water. It can, therefore, keep the water clean so that your fish will always be healthy and happy in their artificial surroundings.

I agree with the general premise of this, but would like to add the following caveat if you didn't already have it in mind.

Good, robust filter media can absolutely help keep the water clean and keep the fish healthy and happy. You just have to remember to clean it on a regular basis so that the solid waste it catches is actually removed from the tank - if it's still in the filter it's still in the tank.
Although it may not look that way because it's out of sight in the filter, not cleaning the filter is no different from leaving solid waste lying on the substrate. Which is to say that it wil just decompose and produce excess NO3, being recirculated over and over again in the case of an uncleaned filter.

As mentioned, I rinse my filter media 3 times a week on Sunday+Tuesday+Thursday during those days' water replacements, and I would not recommend doing any less than this - in fact, every day is perfectly fine. It's a simple matter of rinsing in old tank water until the water is clear, and in doing so 3 or more times a week, you remove any solid waste that would rot into NO3 had it not been cleaned out.

[MultipleTankSyndrome]

Which brings me to my next point. Because of all that biomedia, designating some in your filter that you never or hardly ever rinse is no longer a concern.
This is my favorite thing about the built-in biomedia because I can easily rinse out everywhere in my filter that collects gunk 3 times a week, without ever having to worry about damaging the beneficial bacteria.

Using the best aquarium filter media will ensure that your aquarium will always be clean. The filter media is responsible for catching most, if not all, of the solid waste suspended in the water. It can, therefore, keep the water clean so that your fish will always be healthy and happy in their artificial surroundings.

I agree with the general premise of this, but would like to add the following caveat if you didn't already have it in mind.

Good, robust filter media can absolutely help keep the water clean and keep the fish healthy and happy. You just have to remember to clean it on a regular basis so that the solid waste it catches is actually removed from the tank - if it's still in the filter it's still in the tank.
Although it may not look that way because it's out of sight in the filter, not cleaning the filter is no different from leaving solid waste lying on the substrate. Which is to say that it wil just decompose and produce excess NO3, being recirculated over and over again in the case of an uncleaned filter.

As mentioned, I rinse my filter media 3 times a week on Sunday+Tuesday+Thursday during those days' water replacements, and I would not recommend doing any less than this - in fact, every day is perfectly fine. It's a simple matter of rinsing in old tank water until the water is clear, and in doing so 3 or more times a week, you remove any solid waste that would rot into NO3 had it not been cleaned out.

Some updates to this. I have had an experiment going on for a month, where I save the filter gunk that I rinse to see just how much there is.
What I've saved up is even underestimated from normal/actual figures, because there have been many more 'fast' days and 'light feeding' days than I intended, and as I wait for the gunk to settle in its rinsing bucket before pouring off the rinsing water to get just the gunk, some of it decomposes into that water as liquid NO3.

Despite that, though, I've STILL ended up with enough gunk to fill a 1/3 liter/328 mL jar. And all that from only 9 one third grown roseline sharks and 24ish kuhli loaches of various sizes - I can only imagine how much gunk there will be when I have all my planned fish and they all grow up.
I'll put a picture of the gunk later. All I can say for now is that I'm happy beyond words that I rinse my filter 3x a week instead of just once a month as per most instructions, because if I didn't, over 1/3 liter of blackish green gunk would be in the filter and fouling the tank water faster by the minute.

[NancyD]

OK an interesting experiment but that seems like maybe overfeeding or a subjective way of measuring the filter gunk. I always have plants so there's some debris even with prefilters. Detritus can be from poo, uneaten food, & in my tanks, plant debris, it all looks the same when it breaks down. I know you don't have live plants...& you change lots of water often with vacuuming...So where's all this "stuff" coming from?

[MultipleTankSyndrome]

I'm personally very skeptical it's overfeeding. I have ran into that problem before, but the only times I've ever really overfed them were when they were new and I didn't know just how much food to give, at which point they all got greatly bulging tummies.
Now that I know how much to feed, the normal feeding routine of whatever they can eat in 30 seconds to a minute, 2x a day leaves them with either no bulges in their tummies or only very, very slightly bulging tummies. This is also the feeding routine that leaves a visible (but not enormous) amount of gunk on the prefilter between tank and filter cleanings, as would be expected from how much gunk I get from rinsing everything altogether.

Honestly I have no idea how objective or subjective saving the gunk and going off its final volume is. That was the best way I could think of to quantify it.

I think it's mostly, if not entirely, just fish poop, as both the kuhli loaches and (surprisingly) roseline sharks are very good at getting every last scrap of food even when it falls in the nooks and crannies of the fake plants where one would expect them to miss it. There are 2 things I can think of as the causes of all the poop:

-I'm underestimating the bioload of the roseline sharks. They're closely related to goldfish, which of course have a very high bioload, so it would make sense that they have a somewhat high one too even if it's not something most fishkeepers would inherently expect.

-The biofilm in the diets of both (but especially the kuhlis) is acting as roughage which increases the poop load much more relative to amount eaten than pellets or frozen food. I almost always see at least a few kuhlis nibbling biofilm (off the tank walls, off the decor, probably even off the sand), and the roselines will nibble biofilm off the side of the tank walls much more often than I expected, a couple times a day.

[NancyD]

OK, you're missing a few points. Both fish poo & uneaten food look exactly the same in filter media or vacuumed out water/debris. How are you telling the difference? & this is based on 1 month's worth of (iffy) data?!

Roselines are NOT the same as any goldfish in body mass, food consumption, temp, food preferences &/or waste production You're not comparing similar fish although they are very distantly related...this is not a valid assumption...Do more research before you just guess or hope to find a "right" answer to your ideas.

We all understand you want to keep your loaches as well as Emma & Martin did at each of their different times & places...& ways. You do know they had different water in different continents?...& how many loaches bred for them?

If you want to look at successful keeping & especially breeding of many loaches, look to Mark Duffill & his FB loachfanatics page & join...you might be surprised how easy he & others makes it seem oftentimes. I may have suggested that before...

[MultipleTankSyndrome]

OK, you're missing a few points. Both fish poo & uneaten food look exactly the same in filter media or vacuumed out water/debris. How are you telling the difference? & this is based on 1 month's worth of (iffy) data?!

Roselines are NOT the same as any goldfish in body mass, food consumption, temp, food preferences &/or waste production You're not comparing similar fish although they are very distantly related...this is not a valid assumption...Do more research before you just guess or hope to find a "right" answer to your ideas.

You just reminded me of 2 things I thought I did mention but must have forgot. Must have mentioned them somewhere else.

-1: At every feeding I turn off filters and pumps so food isn't blown into the filter or places where the fish cannot get it, I always try to feed food where it is fully accessible (so in open water for floating and onto the substrate as far from decor as possible for sinking), and should there be food in/under decor after a feeding I will lift up/shake off any decor that food went in/under, to get the food to where the fish can eat it. I'm sure at some points there have been uneaten food, but with this method there really doesn't appear to be much or any.

-2: Even after fast days, let alone normal feedings, I will always see at least a few of the kuhlis or roselines pooping strings of poop of a decent length (it's not stringy or white, rather brown and as thick as expected). And of course, since I can't watch them all the time, let alone the 12 hours when the lights are off, they make all the more then. This is very much like goldfish, even if they are not close (see 3), hence my assumption.

-3: Perhaps roselines are not as closely related to goldfish as I thought. Looking on Wikipedia though it seems they're reasonably close to bala sharks and filament barbs, and owners of both I have spoken to have said their bioload relative to their size will take you by surprise.

We all understand you want to keep your loaches as well as Emma & Martin did at each of their different times & places...& ways. You do know they had different water in different continents?...& how many loaches bred for them?

If you want to look at successful keeping & especially breeding of many loaches, look to Mark Duffill & his FB loachfanatics page & join...you might be surprised how easy he & others makes it seem oftentimes. I may have suggested that before...

Yep you have. I just wish it wasn't Facebook.....

[NancyD]

I'm not much of a FB person either. But I'm 1 of very few who still visit this site & post regularly if at all.

So what do you base your roselines vs goldfish diet & pooing on? AFAIK goldfish should be fed a diet heavy on plant materials but most? barbs like or do better on a diet higher in proteins but with some veggie materials. Many "carp" survive temperate freezing temps, barbs are more subtropical & cannot live in temps much below mid 50Fs for long at best. Neither do well at higher temps, say low 80sF+ for very long term.

Of course GF & barbs are vague terms, for well, many "carp relatives".

So too are "loaches" diferent in temps preferences. Most, or at least many, are "tropical", some are subtropical for temp preferences. Many "Chinese" & "weather" loaches are more cool or even cold water fish. Sometimes difficult for us hobbiests to meet their needs even if we can find them. & then there are "hillstream loaches" not so much a temp preference than a high flow & high oxygenation rate but they're all interrelated. I know you know that...

[zgleason]

It may not appear that way as it is hidden in the filter. However, not cleaning it is the same as leaving solid waste on the substrate. This means that the filter will eventually decompose and release excess NO3. Then, it can be recirculated again and again if the filter is not cleaned. the backrooms