Anaerobic Bacteria And Such Pockets In Substrate

Discussion in 'Advanced Freshwater Aquarium Topics' started by Travisb1297, May 18, 2019.

  1. Travisb1297New MemberMember

    Hello, I am new to this forum, so please correct me if I am doing anything wrong or breaking any rules.
    Anyways, I have a question about anaerobic bacteria and the pockets that the may form in sand or other substrates that have toxins. Please correct me if I am wrong about any of this. These bacteria thrive in oxygen depleted parts of the tank such as low in the substrate. They "eat" nitrates and release nitrogen gas I believe. They also "eat" something else and turn it into hydrogen sulfide(this may be wrong but is what I have found said most) A while back I ran into a post that mentioned Hydrogen Sulfide was toxic, of course, but when exposed to oxygen, became non toxic. I went and did some research and I think it confirmed this. I was wondering if it can harm fish in the process or if I am completely wrong about this whole thing?
  2. kallililly1973Well Known MemberMember

    I use sand in all of my tanks and have heard of anerobic pockets while i think it is true that they can form and affect fish i've had no bad experiences with them. i think it is a very rare occurence like if the substrate is never touched for a long period of time. Others will chime in with more info than i can provide.
  3. Travisb1297New MemberMember

    Do you stir your sand on a regular basis to prevent them?
  4. angelcrazeWell Known MemberMember

    I have anaerobic bacteria in my 90g. I poke the substrate periodically before a water change to release built up gasses. The gasses exit the water in bubble form and into the atmosphere. There is no odor (maybe there was at one time), but now that the tank is fully rooted with plants, I think that helps to take care of it.

    According to this link, it says other bacteria eat the hydrogen sulfide in a healthy tank

    Anyway, I've had dirted tanks with anaerobic bacteria for years, no problems with any fish and absolutely fully processed nitrates.

    But if you want to avoid it, you should be safe if you keep your sand bed under 2" and plant it well. Pool Filter Sand has a larger grain than play sand and works well imo to prevent compaction.
  5. Travisb1297New MemberMember

    Ok. Thank you for your help.
  6. DanInJakartaValued MemberMember

    I don't think that the bubbles are harmful. Nitrogen if I remember correctly. If face, that was the purpose of the deep sand beds of the past.
  7. WraithenFishlore VIPMember

    If you somehow develop a bacteria that gives off a sulphur smell, that's the one everyone is afraid of. I haven't run across any real world proven occurance of fish being harmed by a release so I don't worry in the least. My current substrate is an inch of dirt, with an inch or two of sand on that, with a cm to 5 inches on top of that of fluval stratum. The stratum is new but until a month ago I can guarantee nothing dug around my substrate. Now that pond snails are everywhere, I'm sure it's being dug through.
  8. angelcrazeWell Known MemberMember

    @Wraithen Actually I have come across some real world issues. It was my mom lol, she removed a large Amazon sword plant from a dirted tank. The release all at once poisoned her fish. I suspect she really made a mess tho after seeing her plant :Yikes!:

    A little bubble here a bubble there and it doesn't hurt. I've said before maybe if a small fish swam into a bubble (hydrogen gas), it might disorient him for a bit, but nothing serious. The danger is accumulating hydrogen sulfide and releasing it all at once, or a big cloud.

    I'd like to learn if there's a way to prevent hydrogen sulfide from forming, I'll post if I find something...........Oh yes, I did read about it lol.
    That's why I keep the tank very well planted with roots aerating the substrate. Before the tank was packed with plant roots, I might have noticed a sulfur odor when poking the substrate at times
    Last edited: May 19, 2019
  9. WraithenFishlore VIPMember

    Generally, a planted tank will prevent a big buildup. The roots keep spreading. Snails will also keep the substrate moving plenty, and some people methodically poke the substrate. I get bubbles all the time. They dont stink so I dont worry about them.

    How did the gas not have anywhere to go but into the water in your mom's tank? If she was pulling the sword up, the gas should have popped at the surface and dissipated quickly.
  10. angelcrazeWell Known MemberMember

    Trust me, she made a mess. It's a 29g, so the sword and it's roots were the entire tank. If the tetras were right there because they had no where to go, it was too much all at once. Does hydrogen sulfide pop right up to the surface? If it was mostly sulfide gas and not nitrogen gas? Idk, it happened, she removed a large sword and some or all of her tetras dropped dead. Something went wrong, I figured out had to be sulfide.
  11. WraithenFishlore VIPMember

    I'm not trying to sharp shoot you, just understand exactly what happened. These stories usually have quite a few things that could have caused the deaths, especially with tetra species. I've had a few drop dead within a few hours of adding excel, but my remaining 5 never react to it.

    The released gas should have shot to the surface and popped. If there was so much sulfide gas dissolved in the water it would stink forever, but decaying matter in the substrate could also have caused a bad smell. I go by smell a lot in my tanks. Nitrite levels can be smelled easily in my tanks. If one of my tanks smells like fish, it's always nitrites. If it smells like dirt, its healthy as long as my nitrates aren't crazy. I have yet to smell farts or death in my tanks so I dont have experience in that. Sulfide gas is pretty stinky, so a plume that would kill your stock would definitely be smelled by anyone anywhere near that tank.
  12. angelcrazeWell Known MemberMember

    Fair enough! You are probably right, I guess I just assumed :( Shouldn't have done that! She was overfeeding as well. And I don't even remember the story too well.

    I agree with you on the smell thing lol! I am very particular about odors, and I purposely also smell my tanks hahaha! Nice to learn about the nitrite odor, that's cool!

    I have smelled sulfur. I also have smelled cyanobacteria. Let's just say they both have a very distinctive odor haha!

    I also helped take down my friend's 75g, the whole condo reaked so bad I was fighting severe nausea to put it politely. I had to keep leaving for air. She used a huge layer of some reptile soil that I believe is mostly coconut fiber. It was horrendous!
  13. happyscrubValued MemberMember

    1. You need at least 6 inches of fine sand substrate to create a zone for those bacteria.
    2. There is a myth of the gas being dangerous to fish. All those gasses neutralize when hit with oxygen which WILL be in your water. The gas is only deadly UNDER the substrate.
    3. People say you should poke holes and turn it over a lot to keep the gas from building up. This is silly and defeats the purpose of a deep sand bed. You want to not disturb it because if you keep disturbing it, you keep getting oxygen into the zone. Even a lot of the suggestions animals that dig don't go so deep.

    this guys has good videos on the subject

    find his playlist.
  14. angelcrazeWell Known MemberMember

    Inches or cm?


    I have 3 plecos and babies, 10 amano shrimp grazing the surface of the substrate to help slow exchange. I poke the substrate with a thin skewer stick to help with this also. I poke substrate maybe every 6 months and only a little bit of gases come up. Most of the anaerobic bacteria is still there. But I could stop using my skewer too. I will look more into this tx. All I know is it's working for me, no nitrate detection for years.

    But I do agree, I'm not sure why anaerobic bacteria isn't typically used in freshwater. I want to know more about how anaerobic bacteria affects fish.

    Is this an option?
    Someone decides to remove a large amazon sword first thing in the morning from a dirted tank with anaerobic bacteria. Could the amount of anaerobic bacteria released at once exceed o2 levels at the bottom of the tank (where fish are when sleeping) and poison the fish? Is is possible?
    Last edited: May 25, 2019
  15. WraithenFishlore VIPMember

    I think it's because most freshwater starts with mistakes, and it's the side of the hobby where people usually try to be cheap. If you're spending nearly a grand on a large tank setup, a lot of people still balk at spending a few hundred more on sand. I've got over 6 inches in the back of my layers, but I'm sure there's anaerobic bacteria throughout.... or at least was until pond snails hitched a ride in.
  16. angelcrazeWell Known MemberMember

    I'm trying to grow anaerobic bacteria in my 120g by adding dirted containers. The weird thing is I get a buildup of gasses in these containers. What is It? The containers are around 3" deep and capped with PFS. It doesn't smell.
    Last edited: May 26, 2019
  17. WraithenFishlore VIPMember

    If its actually dirt, the gas is stuff dying in there. It's super common when using dirt in tanks, it will subside for the most part in a few weeks. If you didn't sift out tiny twigs and stuff, you will have it going for a little longer. I sifted a huge bag and still had some pockets of air for a while. It never stank though so I let it do its thing. Now that I'm injecting co2, my soil seems to bubble pretty frequently in the evenings.
  18. angelcrazeWell Known MemberMember

    Interesting. I knew the soil breaks down and produces ammonia. Oh and I did sift it ;)
    Edited because I went off track :oops:

    I was reading an old Fishlore thread talking about using dirt to grow anaerobic bacteria.
    OP's thoughts were since 'soil' is more compact than sand, that a thinner layer may be sufficient for anaerobic bacteria to establish.

    Anyway, I have never had issues with anaerobic bacteria or soil hurting any of my fish. I am going to continue setting up my tanks this way.
  19. RSababadyWell Known MemberMember

    I am a bit confused, maybe some can help me.
    Some of the posts in this threads refer to situations where the tank owner doesn't want the anaerobic bacteria to form, while others refer to situations when the substrate is built to provide for a colony of anaerobic bacteria to build up. So it seems as though we have two situations:
    1. A tank with filters and anaerobic bacteria is not really required. Plants or WC reduce the NO3 level
    2. A tank with no filters so the substrate is thick and is the home for the nitrifying bacteria and the anaerobic bacteria.
    Is that what we are referring to?...or am I missing something?
  20. WraithenFishlore VIPMember

    Mostly. There is a ton of fear mongering about the bacteria causing a dangerous buildup that nukes a tank when it finally spouts up. I've started questioning that theory since I cant find a place where it is the only cause of death. There's usually a lot of things going on and the blame game starts there. I see no reason why anyone needs to avoid anaerobic bacteria, but most people shouldn't be trying unless it's just for fun. I say that because it is kind of a fragile system and can be extremely frustrating for people that have it as a goal. It can take forever to build up a good colony. It's a good way to go though for someone wanting to go longer between water changes.