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I am about to redo the filtration on my 120 planted rainbow tank from scratch. I *want* to ditch my two Eheim 4+ 600s in favor of one strong external pump (that will branch off to various returns for flow purposes) and a Nu-Clear mechanical (with option for carbon or Purigen) filter.

QUESTION: In our planted tanks, with (in my case, 2” of) black blasting sand covering my 18” x 60” footprint, do I need a BIO filter? The Nu-Clear would be an outstanding mechanical filter, powered by a strong external DC pump, where the retur flow is branched with ball valves three ways: 1) run with an inline Vecton 2 600 UVS, and 2) provide flow to my CO2 cerges and 3) boosted flow throughout the tank.

In this plan, there would be no biological media in a filter. The sand would house the biological bacteria needed to control ammonia. My tank is mature: it’s been running since May of this year.

Anyone do this currently? Anyone go without biological media and just use their sand for that? (I feel like someone said they did...)
 

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I feel there will be many schools of thought on this one...

How many fish are in this tank now?

No matter what, if you remove all the bio media and rely on the sand alone, you will see ammonia spikes. Frequent testing and water changes will be necessary. If in the long run the sand can maintain the tank is the key question.

In the filters the water is forced through the bio media. This allows for the BB to work. Although you have a deeper bed of sand, you will not get nearly the same flow through the sand.

It is possible to run with no filter media, yes, but I would not stock heavy!
 

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My 29-gal is heavily stocked and I haven't used biomedia in many years. BB already exist on every surface in your tank (including substrate) and tubing. Plants will get more access to ammonium (which they prefer) without biomedia in a filter and BB will expand, as needed, to deal with any NH4 that remains. Although I've never measured a TAN spike, if your pH is below 7 there will be none of the dangerous NH3 present, it will all be NH4. So it wouldn't matter if you did get a TAN spike.

Qualifier: I may be resuming use of biomedia. I've been reading some aquaponics and hydroponics articles that claim that NO3 is taken up better, beginning at pH below about 6.2, than ammonium and that the excess ammonium that is not taken up may interfere with the uptake of calcium, magnesium and potassium. Additionally, too much NH4 vs NO3 may actually cause N limitation at these low pH levels. So far in my reading, it seems mainly applicable to the root zone. Apparently, a ratio balance in favor of NO3:NH4 becomes important as acidity increases. I haven't gathered enough yet to make a decision. Perhaps other members may have knowledge of this possibility.
 

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Can't say anything about plants liking ammonia or nitrate more, BUT I can talk about fish and biological filters. A lot of this is information paraphrased from the saltwater side of the hobby (surprise! They have sand there).

So with the saltwater side of the hobby, you can theoretically do a "negative space aquascape" (minimal rock, designed to take a large volume of space up) and without sand. There is a LOT of surface area in the tank, and the glass/sponges/protein skimmer/every surface gets colonized by beneficial bacteria. You will see a LOT of posts about tanks having mini-cycles when the hobbyist removes the sandbed, as 1) detritus is resuspended, and 2) beneficial bacteria are removed. So, in conclusion, you MIGHT be able to do with no biofiltration and just a sandbed.

BUT, there is one catch. Saltwater tanks frequently have a very high turnover rate. It ranges somewhere to 15-30+x the tank (ex. a 10 gallon tank might have 150-300+ gph flow on it). This means that there's a lot of oxygen blowing around the tank, and a more even distribution of nutrients for everything to get at it. Additionally, saltwater tanks tend to run heavily understocked. There's usually one 1-2" fish in a 10 gallon tank, and a 55 might be at stocking capacity with 8 3"-5" fish.

In your case, how much flow are you going to have going through the tank? While turbid (random) flow is not a requirement, is there at least enough flow so that there are minimum dead spots? Additionally, how many fish are in your tank?
 

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Seems there are many variables to a no biological media system that would have to be taken into consideration before we made the determination that its not needed:
PH
Planted/not planted/lightly planted
Livestock density- stocking density with 2 prior considerations in mind.
Livestock sensitivity- in combination with previous 3.
 

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I run multiple HOBs in my 125g for mechanical polishing only without inserting any biomedia, but I install a dedicated circulation pump to blow oxygenated water over all surfaces.

You don't need dedicated bio media in your filters if you have good oxygenated water turn over as your tank walls, substrate, decors and all contact surfaces are practically in situ bio media.

On the other hand, it is useless and may even be harmful if you have a lot of bio media in your filter but allow it clog up and not thoroughly oxygenated.
 

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Seems there are many variables to a no biological media system that would have to be taken into consideration before we made the determination that its not needed:
PH
Planted/not planted/lightly planted
Livestock density- stocking density with 2 prior considerations in mind.
Livestock sensitivity- in combination with previous 3.
Agreed. I would never consider my current no-biomedia setup in a non-planted tank. It's absolutely critical, with a heavy fish load, to have a good and healthy plant mass if attempting no-biomedia in a tank with pH greater than 7.

Additionally, if anyone is considering moving to no-biomedia, do it slowly, over several weeks, to allow both plants and biofilm to adapt slowly to the change. Last thing you want to do is to kick things out of balance due to sudden changes. When I converted, I reduced my biomedia by about 20% of the original load every week. Obviously, that took me five weeks.
 
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The Nuclear filter cartridge has a pretty sizable central cavity. I suspect you already know this and were planning to use this for a large bag of carbon or Purigen. You could instead use the space to have two media bags. One with carbon or Purigen, and one with a biomedia like Seachem Matrix. Might be usefull if you want to max out the rainbow herd!
 

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Every water facing surface in the entire aquarium system is a home for beneficial bacteria to colonize- including the mechanical filtration media. The BB will propagate to a level in balance with the food (Nitrogen compounds) available to the bacteria no matter what surfaces the bacteria has colonized on. Rinse the crud out of the mechanical filtration media in tank water instead of washing it thoroughly to keep from loosing all the bacteria that is on the media. Although you will still loose a considerable amount of the bacteria the remining will recolonize quickly.

Water flow is important to exposing the BB to its food source. This is why BB grows denser colonies on "biological" media that has a lot of flow through it.

I have a Nuclear cartridge filter that I tried for a while. Even with a good pre-filter the cartridge plugs way to quick for my tastes! I had to put the pump on the exhaust side of the Nuclear filter because the filter would always start leaking drips of water when the cartridge was full with the pump pushing water through the cartridge.

I switched to a Diatomatious Earth pool filter and couldn't be happier! Much cleaner/clearer water than every cartridge filter I have tried and MUCH MUCH less maintenance than all of the cartridge filters I have tried! https://www.monsterfishkeepers.com/forums/threads/monster-diatomaceous-earth-de-filter.434493/

The rate at which a mechanical filter will clog is directly proportional to the surface area of the filter (assuming a constant mesh size). A DE filter coats the filter mesh with a layer of Diatomatious Earth that provides 100x more filter area than the mesh it is coating AND the pore size of the microscopic diatom shells is MUCH finer than the usual pore size of a cartridge filter... fine enough to filter out fungus, free floating algae, and free floating bacteria. When the entire surface area of the diatomatious earth is plugged you simple knock the DE off of the filter screen then turn the pump back on which recoats the screens with a fresh layer of DE exposed to filter the water. The regen of the DE takes me about 30 seconds to do with the DE pool filter I linked to above.

If you are set on using a cartridge filter many of our aquarist brethren highly recommend this cartridge filter that has about 80% more surface area than the Nuclear, is reported to be easier to change the cartridge in, and has MUCH less expensive cartridges available than the Nuclear. https://www.amazon.com/Pentair-R172504B-Cartridge-Replacement-Dynamic/dp/B001O9VESS/ref=sr_1_68?dchild=1&gclid=Cj0KCQjwuL_8BRCXARIsAGiC51CPJ5jnL9LxoWk4aDXKRXWH2Cssvbd707q4L9Vh9OldZif2G7yxubgaArzaEALw_wcB&hvadid=409956821440&hvdev=c&hvlocphy=9033152&hvnetw=g&hvqmt=e&hvrand=10114805571269901842&hvtargid=kwd-1461279300&hydadcr=24630_11410025&keywords=pentair+cartridge+filter&qid=1603303506&sr=8-68 I HIGHLY recommend a DE filter over a cartridge filter though! :)
 

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I am about to redo the filtration on my 120 planted rainbow tank from scratch. I *want* to ditch my two Eheim 4+ 600s in favor of one strong external pump (that will branch off to various returns for flow purposes) and a Nu-Clear mechanical (with option for carbon or Purigen) filter.

QUESTION: In our planted tanks, with (in my case, 2” of) black blasting sand covering my 18” x 60” footprint, do I need a BIO filter? The Nu-Clear would be an outstanding mechanical filter, powered by a strong external DC pump, where the retur flow is branched with ball valves three ways: 1) run with an inline Vecton 2 600 UVS, and 2) provide flow to my CO2 cerges and 3) boosted flow throughout the tank.

In this plan, there would be no biological media in a filter. The sand would house the biological bacteria needed to control ammonia. My tank is mature: it’s been running since May of this year.

Anyone do this currently? Anyone go without biological media and just use their sand for that? (I feel like someone said they did...)

fake it?
take the media out of the filters , bag it up in a well rinsed /de-chemicaled or ideally new rinsed laundry bag (those drawstring permeable sack things) or similar permeable bag and place it in the tank.
next add new foam to the filters for mechanical scrubbing then run it and monitor levels, if all still tests good after a day or two start removing the old media in stages , eventually you'll either have two mechanical only filters and the tanks bacteria coping or you've hit spiking levels and abandoned the idea and put all the media back into your filters , either way you got a definitive answer at that point.
 

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I recently bought 1L of Seachem Matrix, following rave reviews and suggestion by one popular yourtube Chanel. It looks very porous, indeed.
I put about half of it (0.5L) in canister filter running on my 40gl, and about 1/4 of it used for 10gl tank. Suddenly, the TDS in both tanks started to rise, about 10ppm per day. It took me a while to realize that Matrix is the culprit. I removed most of it, and the TDS stabilized. I placed all removed Matrix media in a bucket of water, and the TDS is increasing, although at slower rate.

Anybody had similar issues? Would it get washed over time and would stop leaching (Ca, Mg or whatever)? I am kind of disappointed, especially since this is not mentioned in product description. I also could not find anything about this on the net.

additional info: the tap water is at TDS 160ppm. Both tanks are matured, heavily planted stable tanks. One is low tech (essentially with no ferts added), and one is high tech (following a lean EI).
 

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The manufacturers of commercial bio-medias would have us believe that beneficial bacteria only lives on/in their media in the filter. Commercial medias often brag that their media is best due to the vast surface area with all those nooks and crannies and micro holes. Whether gravel or sand, there is far more surface area in the substrate than in any filter...not to mention the countless other life forms that make up the true bio-filter. My filters only contain sponge material. My 60g has 3-4" of pool filter sand, untouched except for plant maintenance for over 8 years. I have fast growing floating water sprite.
 

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Another small point which is more a matter of how we speak is that I would not call a tank "fully mature" at six months but feel it about half ripe! Does a tank with plants and fish who change as they grow, ever get fully mature or are they still going through constant changes!
Every change I make is based on doing it slowly and watching what else is changed. I do not favor totally doing away with an area where I can keep a small "reserve" of good bacteria, just in case something major goes wrong in the tank. It allows me a bit more freedom to do anything like a major rearrange, etc.
 

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I'll go a step further to suggest that we've also been somewhat conditioned to think that sponge material in a filter is for mechanical filtration only. In fact, sponge material (aka bio-sponge) is a great platform for beneficial bacteria. Proof of this are the many large fish rooms out there that rely solely on air driven sponge filters.
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So although I may rely primarily on the bio-filtration of the substrate in my established planted tank, my filters that are all filled with sponge material, will also contain beneficial bacteria. I just don't need overpriced bits of plastic, ceramics, or rocks.
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Disclaimer: I will confess that I do have two large baskets of (BBQ type) lava rock in the 40g sump on my 110g bare bottom stock tank.

 

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Is there anything folks on this forum like to talk about more then filtration? ;P

I'm half serious with that question, its such a hot topic because everyone has an opinion since what they are doing (whatever it is) tends to work pretty good. This alone should tell the OP that filtration options offer a WIDE therapeutic window (to ruthlessly co-opt a term).

To answer the original question though of whether you need specific biological media (meaning ceramic discs or similar) in your filter to keep your tank healthy the answer is a qualified no. The qualification being around how high stocking involves. If you are stocking your tank like its a fish store tank, then yeah.. you need something as biomedia. If on the other hand you either have it understock to slightly overstocked then you are going to be fine with the setup you described.

As mentioned everything that comes in contact with the water in your tank is going to grow bacteria. There is nothing magical about the ceramic discs, bio balls, or whatever. They just are providing surface area.

I can't help but point out though that there is a semantic problem here as well that we should probably clear up. Some folks may be referring to biomedia meaning a thing sold to us as biological media (like ceramic discs etc) while others may be referring to biomedia as anything in a filter that grows bacteria. If you put a piece of sponge in your filter for purposes of cheap, reusable mechanical filtration. That sponge may be there as 'mechanical' filtration but you can be 100% certain it is also growing bacteria and providing biological filtration as well. This is my preferred method of filtering my tanks. I use just sponge in my filters and typically only have a bag of ceramic rings in there for the purpose of seeding new tanks as needed. So that means right now that out of my 3 tanks, only 1 has some ceramic rings. /shrug just something to keep in mind. Hopefully some of this ramble on my part is helpful.
 

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I wont be throwing my biological media out anytime in this lifetime, but--- question...
I have also always heard ( and yeah, this could be false) that beneficial bacteria grow most abundantly in areas of highest oxygenation and food. This being located in the filter.

This quote explains it better than I could :

"The good bacteria can live on any surface in the aquarium. However, like all organisms ever, they concentrate their populations where their limiting factors are best met. In an aquarium the two things that are the most limited for the bacteria are food and oxygen. Filters provide flow which provides food and oxygen. The surface area of the biomedia provides a surface for the bacteria to grow on where they can sit and allow the oxygen and food to come to them. At the end of the day it is not the biomedia itself that is anything magical, it is nothing more than surface area per volume. The bacteria are happy to grow on any surface, but they do not simply spread out evenly throughout the aquarium. Although any surface area in the tank (decor, glass, substrate, etc.) are otherwise perfectly acceptable, they do not have the same flow as the filter and therefore will not house significant colonies of bacteria."

Cycling and Understanding the Good Bacteria ? Advanced Aquarium Concepts

Is this incorrect?
 

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This reminds me of the repeated claim that we must have 4x to 10x flow through a filter for good filtration...almost borders on nonsense. Water is brought into the filter from the tank, so there is no more O2 there than in the tank. It has been suggested (not remembering where) that the flow through the filter is fast enough to inhibit the efficiency of beneficial bacteria to process ammonia and nitrites (but maybe if we move water 4 to 10 times an hour the bacteria will have more chances to catch the food <hehe>).
I tend to believe that the very best bio-filtration happens with the zillion creatures that inhabit the substrate. But I just can't find my soap box this morning.
In any case, I used to buy into the commercial bio-media marketing hype, but after years of my own experiments and testing, I'm convinced that sponge material is every bit as good or better, cleans easily, and lasts nearly forever. Still, in the established tank, any BB in a filter is dwarfed by that in the substrate. That's my story anyway and I'm sticking to it. :)
 

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This reminds me of the repeated claim that we must have 4x to 10x flow through a filter for good filtration...almost borders on nonsense. Water is brought into the filter from the tank, so there is no more O2 there than in the tank. It has been suggested (not remembering where) that the flow through the filter is fast enough to inhibit the efficiency of beneficial bacteria to process ammonia and nitrites (but maybe if we move water 4 to 10 times an hour the bacteria will have more chances to catch the food <hehe>).
I tend to believe that the very best bio-filtration happens with the zillion creatures that inhabit the substrate. But I just can't find my soap box this morning.
In any case, I used to buy into the commercial bio-media marketing hype, but after years of my own experiments and testing, I'm convinced that sponge material is every bit as good or better, cleans easily, and lasts nearly forever. Still, in the established tank, any BB in a filter is dwarfed by that in the substrate. That's my story anyway and I'm sticking to it. :)
Not disagreeing at all on any point as things vary so much, the sub definitely has bacteria but I feel it may be a thin layer as compared to media in the filter as there is not water flow going down deep into the sub where we do find water flowing through media. So how how long the tank has been set and not been changed do make a difference in how much we might find and where, so If have no problem with putting some form of hard media in the filter as a hedge against any time that I might want to redo most of the sub as that gives me two places that I know there are a good set of bacteria. Then it also gives me comfort knowing that when I clean the filter after the tank has been running for months and I might knock the bacteria in the filter way down, I can know that the stuff all around the other parts of the tank will cover for any mistake I may make in overcleaning things.
 

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As I read through this, it seems to me that all of these points are good. Fundamentally, I suspect that there is not that much for the BB to do, no matter where it is. In a mature tank it will rapidly expand to the level of the food supplied (like snails), namely: ammonia. If ammonia was a big presence, I suspect that we would see quite a lot more deaths with even slight disruptions to substrate and/or filter media. We would also all be monitoring total ammonia with great frequency and concern. I don't remember the last time I checked TAN on my display tank.

Anecdotal experiences: I have always had overly-stocked aquariums, with and without plants, and cannot recall a tank wipe-out that could be attributed to ammonia ONCE the BB was established. Before we knew about the Nitrogen Cycle, we threw our spent charcoal and floss out every week and completely cleaned our filters, with no deaths. This was well before CO2 injection, so pH was generally ideally suited to leaving the ammonia in the deadly NH3 form, as opposed to the safe NH4 when pH is below 7. In this case the BB was probably never established in the filter. Often, I'd go a month or more before cleaning, which allowed BB to build in the filter - then threw it all out, with no problem. I have also completely replaced substrates with no bio-media in the filter and, again, no deaths. I've even been without power for days with no problem. In this case the BB in the substrate, and the plants, were undoubtedly critical. This might even make the case that plants take most of the ammonia.

In other words, in a mature tank, I think that BB rapidly meet the ammonia needs of the aquarium on any surface they can find (maybe even in layers) and, if you have plants, that further reduces the ammonia threat.
 
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