So, Maximizing Beneficial Plastic As A Bio Media

Discussion in 'Filters and Filtration' started by Homeslice, Dec 4, 2018.

  1. HomesliceValued MemberMember

    I am a bit dubious as to plastic as a bio media as compared to ceramic rings or other material, per this thread here:

    So, Some Results/questions From My Giant Trickle Filter

    That said, I have questions about using plastic as a bio media, particularly how its basically free from any public trashcan lol.

    So first, bio balls versus plastic pot scrubbies. Bio balls are like some plastic ball, hollow inside or with some sponge thingie inside. Plastic pot scrubbies are a LONG strand of plastic, wrapped over and over and over and over itself, again and again. It seems that plastic pot scrubbies provide MUCH more surface area for bacteria to live on, so, assuming the same amount of oxygen, ammonia, etc., are not plastic pot scrubbies much, much better area versus area? It just seems a no brainer to me.

    Second, are there "bad" plastics, as opposed to "good" plastics? I ask this because I sometimes see people say, as a DIY plastic alternative, use water bottle caps. But, why not just use the entire water bottle?

    Third, isn't the best option as far as plastics and bacteria go is to use the smallest, and thinnest, plastic shavings or strings or whatever? Assume you have the smallest plastic area that a beneficial bacteria can live on. It can live on all sides of that. Now, combine two of those. That automatically creates an area, where they are joined, where bacteria cannot live. It seems to me that whatever is good plastic you want to shred it, slice it, carve it, etc. into the smallest pieces you can, obviously dealing with the issue that you have to be able to pick it up, wash it off, put in the aquarium, etc.

    I would sure appreciate any thoughts! Thanks!

  2. AquaticJFishlore VIPMember

    To be simple, ceramic and lava rock are waaaay more porous than plastic.

  3. AuthmalValued MemberMember

    Yep. I've started using lava rock. It's a whole lot cheaper than manufactured media, and naturally occurring and sustainable. Just needs a rinse to get the dust off.

  4. CichlidudeWell Known MemberMember

    Plastic is only good in moving media filters.
  5. AuthmalValued MemberMember

    Oh. Dang. I know what you're talking about. They look super cool. I don't know how good they actually are, but they're certainly a conversation piece. I just can't place the name. Fluidized filters, maybe?
  6. CichlidudeWell Known MemberMember

    Fluidize = Moving media
  7. HomesliceValued MemberMember

    Of this, I have no doubt. You take any piece of plastic of similar size to a ceramic ring or lava rock, the plastic will have almost zero "poreosity" in comparison. Its is just a solid so bacteria can only live on the outside, with all the interior wasted.

    But what I am saying is imagine if you could shred that plastic piece into hundreds, thousands or millions of pieces. Each just big enough for a bacteria to live on it. You would no longer care about poreosity in the least IMO - you have maximized the total area bacteria could grow on.

    Same for the ceramic and rock too - while being porous means lots of bacteria can live on the inside, there is most surely space where they could live wasted because obviously it is not going to be porous to the extent that there is absolutely no places where there is excess material that could not be divided to create additional living space.

    There are other issues, of course, like compaction, getting oxygen rich water through the media, etc. But I just think if, at least on a theoretical basis, you could make the plastic filing or what not small enough the porous issue goes away.
  8. HomesliceValued MemberMember

    Chichlidude, if you mean plastic is only good in moving media filters WHEN YOU COMPARE IT TO OTHER MEDIA, that could well be true. But surely it provides a space for bacteria to live, and thus is viable, in a filter or in the tank so long as oxygenated water is moving through it. Logic dictates it. Other media probably works better for sure, I 100% agree with that - see the thread I linked.

    What I am wondering is this - let's say the smallest piece of material a bacteria could live on is 1 micron. Its not, but lets just say that. The question is would a bacteria do better living on 1 micron of plastic? Or 1 micron of ceramic media? Or 1 micron of "sintered glass" or whatever biohome and other stuff is made out of. I don't know if we know the answer to that. Check out that other thread I linked - I *think* they prefer ceramics over plastic, but I'm not really sure as those bio balls in my trickle filter in particular have so much less overall surface area overall as compared to ceramic rings given their poreosity. My question is, if you could shave that bio balls into hundreds of tiny pieces, so its total surface area was proportional to that of a ring, which would the bacteria colonize quicker/do better on.
  9. CichlidudeWell Known MemberMember

    And which bacteria are you talking about. Aerobic or anaerobic?
  10. CrazycoryfishladyWell Known MemberMember


    You could use a very very thin sponge

    The plastic idea works, and I think the "good and bad" comes into play when they start to degrade or lose an outer coating or something.
    Some plastics are considered toxic, especially when left in water meant for drinking or living, which is why not all plastics are labeled food or water safe.

    But a sponge essentially has the same idea as the rocks and sorta plastic minus the cutting it up or crushing it.

    Like the rocks sponges have pores, unlike the rocks, sponges aren't solid inside and can hold bacteria and water in every part, not just porous parts.

    Which is why one sponge filter can be exactly what a 55 needs meanwhile others will struggle using 2 hob or canister filters.

    Pro sponges tank up less space and only need moving water around them

    Con I believe they have to be switched decently often depending on type because they degrade just like everything else.

    Your plastic would be hard to contain, I'm imaging it a bit like a bunch of copper wire scrubbies, just a whole lot of thin sharp pieces with large holes in them and some spots where it's super duper compact.
    You would have to either encase it or bag it to use it in any type of filter rather than just one.
    Otherwise I would have plastic pieces floating out of my 55 hob.

    A sponge you just cut to size, squish in and add a few of them.

    Not that your idea can't work, but I think you may find it more logical to purchase a songe rather than dumpster dive for dirty filter media.
  11. HomesliceValued MemberMember

    I would think both. Check out this video here, where Dr. Kevin Novak talks about using bio-balls in one of his funny sounding filters, which is presumably for anaerobic bacteria:

    I would absolutely love some hard evidence, using my example above, whether aerobic bacteria on the one hand, and anaerobic bacteria on the other hand, would do better on 1 micron of plastic, versus 1 micron of ceramics, versus 1 micron of glass (i.e. that used in "sintered glass" media), versus 1 micron of rock (like lava rock). I'm just not aware of any. So many things in this hobby have just not been thoroughly tested!
  12. HomesliceValued MemberMember

    Hahaha, Crazycoryfishlady, much of what you expressed I was thinking to myself in my head - particularly the need if you have all these very small plastic pieces to contain them to not have them going everywhere. Maybe you put them in those cheap little media bags they sell (which I would guess are themselves plastic). Or I guess if they were buried at the bottom of a deep sand bed they could be contained.

    When you talk about certain plastics being bad, wouldn't the entirety of a water bottle or any bottle that people drink out of be good?

    I only just recently really learned that sponges are also bio media, not just filtration devices. They sound like an excellent bio media. Now my question is - what are SPONGES made of? If it is plastic, then I agree completely it might be the way to go rather than having a plastic junkyard in my tank. :) If it is something else, then my question above about what media do better on, given equal surface area, comes into play - would bacteria do better on 1 micron surface area of plastic versus 1 micron surface area of whatever sponges are made of.

    Thanks so much!
  13. CrazycoryfishladyWell Known MemberMember

    I'm not toally sure which of the plastics are the worse ones, but think about it like having old water.
    We know we can taste a difference in water, especially if it's old.

    If it's uncovered, it simply tastes like dust which is a nasty variety of things.

    If it's covered, water seems to erode it's container and pick up some of the pieces and that comes out in the flavor.

    If you leave water in a plastic water bottle, it tastes, no better described, than like plastic.
    Now it may not exactly be that we are drinking plastic, but I do personally believe that prolonged usage of plastic in water systems or in water bottles in general, eventually starts to make the water taste bad and perhaps "leaks" chemicals that make up the plastic into the water.

    Of course I would have to test this or find info to know if it's true, but water contained in a glass jar simply tastes more like normal water to me versus water in a plastic bottle.
    I know water breaks down all materials at different rates, so eventually glass water has a taste too, to me it tastes slightly metallic almost, but that could also be due to the pipes so that's not really a good example.
    But it's clearly proven moving water breaks things down, which is why I think sponges wouldn't exactly be the best material, and I'm not sure what they are made out of.
    Some are even called foam instead of sponge.
    Any of these items could potentially leach chemicals into the water, but personally based on my hate for plastic bottled water taste, I think some plastics should be avoided.
    Perhaps plastic like from a milk jug would suit better than a water bottle.
    I'm also thinking that with the rigidity of the milk plastic, that bacteria would favor colonizing on it's surface over the flat surface of the slim bottle.
    Not that I know what the bacteria favors.... But it seems logical it would want to hold itself in a crack rather than on a flat surface that could easily move away I guess.
    I guess a lot of this needs testing like you said haha

    We'll have to find out what various sponges/foams are made of
  14. HomesliceValued MemberMember

    Thanks Crazycoryfishlady! Everything you said makes sense. My only thoughts is that I'm not so sure bacteria could even tell the difference between the more rigid (did you mean "bumpy" or "course" or something like that?) surface of a milk bottle compared to the "flat" (did you mean smooth?) surface of a water bottle - I would guess the bacteria are so small that even what seems like a perfectly smooth surface to us is super mountain-ish to a bacteria. But I really don't know.

    I intend to do some investigating and will follow up. Maybe not right away, but I will! :)

  15. CrazycoryfishladyWell Known MemberMember

    Yes that is what I meant, smooth and bumpy lol
    Since milk containers have little crevices on them, as if there are small bumps, my thought was much like makeup, it will seemingly only fall into the cracks.
    Though I guess it really depends on how our bacteria likes to live.

    Certain types of organisms prefer to grow in crevices rather than smooth flat surfaces, but as you said, it is very likely that what seems smooth to us is actually quite bumpy at the microscopic level.
  16. FiscCyningWell Known MemberMember

    Most sponges are made of plastic, so what you’re describing with the finely shredded plastic is essentially just a sponge in unbonded form (and therefore more messy - to the point that it could potentially even damage your filter if the strands get tangled in the impeller). Some folks like filter floss or polyfill in their filters, which would essentially be the finest shredded plastic like you’re describing (but much easier than doing it manually, plus fine enough that they shouldn’t be a threat to the filter mechanics if they come loose).

    As far as water bottles go, bottles that you buy with the water in them are made of plastic that is intended for single use because it will break down over time and leach chemicals into the water. This is why it’s not recommended to wash and reuse these bottles or to leave it in a hot car (the heat accelerates the leaching). You can look at the recycle symbol on the bottom of the bottle to find out what plastic it is. Single use bottles are usually 1. The plastics that are generally considered aquarium safe are 2, 4, and 5.

    The reason people use caps but not the bottles is likely because the caps are made of a different type of plastic (which is why you have to remove them before recycling the bottles). I don’t recall offhand what type of plastic the caps are, but a quick google search should give you the info.
  17. HomesliceValued MemberMember

    Wow FiscCyning, that was EXTREMELY helpful! Thanks so much! Based on what you said it probably makes little sense to try and scrounge around for plastics to grind up and use as media - just use some super cheap sponges or what not. But it certainly helps me to know the 2, 4 or 5 thing to know what kind of plastics I should use, for example, to put on my powerhead to put in meadia and floss or polyfill to use for filtering. I'd guess baby formula plastic bottles, and plastic liquor bottles, are good to go, of which I have lots of haha. :)

  18. AuthmalValued MemberMember

    Who started talking about the 2, 4 or 5 recycle number instead of 1? @FiscCyning ? I must keep glossing over your post. But you're really irritating me. A lot. :mad: Because the probability of your being right is high, which is causing me difficulties.

    It makes sense, since the 1 is the most easily recyclable, that it's also most prone to leaching chemicals. It's less formulated for long term integrity. Sadly, almost all bottles I find are 1, and I'm having a devil of a time finding the other numbers in clear, or at least sufficiently translucent bottles. Alright, back to the search!

    Thanks for the tip. It really does make sense, and even if there are no studies out for it now, *it makes sense*, so I'm assuming it's accurate until I see something definitive that says otherwise.

    Edit. Found it.
  19. HomesliceValued MemberMember

    Authmal - FiscCyning indeed mentioned it - he said "You can look at the recycle symbol on the bottom of the bottle to find out what plastic it is. Single use bottles are usually 1. The plastics that are generally considered aquarium safe are 2, 4, and 5."\

    I'm curious - anyone know what a "3" would not be considered safe? I thought there would have been a consistent scale between 1 and 5, and if 2, 4 and 5 were generally considered safe 3 would be as well. Maybe 3 is some weird different plastic.

  20. AuthmalValued MemberMember

    3 is something like a polyvinyl chloride, if I recall correctly, which is a huge environmental hazard, and I don't think it recycles well. Different uses. Google will have more information.

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice