Strange bubbles from substrate

Discussion in 'Substrates' started by willjones, 4 Jun 2008.

  1. willjones

    willjones Member

    Messages:
    47
    I have set up my first planted aquarium over the past 3 or 4 months. My set up is as follows:
    Roma 240 tank, 2x 40W T8's, substrate is seachem flourite (well washed initially), ehiem 2026, 8W UV unit and dosing with ferropol (TPN ordered and apparently on it's way).
    In the last few days I've noticed bubbles of gas rising from the substrate, and some of the fish not looking that well. I'm not sure what to do about this because my substrate is fairly densely planted and would cause a lot of disruption to stir it up. I tried two 40% water changes in quick succession and things seem a little brighter. Just wondering if anyone had any tips.
    Thanks, will
     
  2. nickyc

    nickyc Member

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    208
    Location:
    Nottingham
    What does the gas smell like?
     
  3. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

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    Location:
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    Yes, as nicky says there is a possibility that there are some anaerobic areas developing in the substrate. Among the products of this are Hydrogen Sulfide gas has the smell reminiscent of rotten eggs. It could be that this gas dissolves in the water and with other contaminants forms sulfuric acid. Try measuring the pH of the tank when this happens to see if it is abnormally high.

    Well fed plants send oxygen to their roots which escapes into the sediment, which stops this type of activity.

    Cheers,
     
  4. Wolfenrook

    Wolfenrook Member

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    336
    Location:
    West Midlands UK
    I think that Ceg means abnormally low as sulphuric acid will reduce pH, not increase it.

    Ade
     
  5. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

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    Yes, sorry, thanks Ade - posted prior to morning coffee consumption. :oops: See if it is abnormally low.

    Cheers,
     
  6. beeky

    beeky Member

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    879
    Location:
    Chippenham, Wiltshire
    It's it's just the odd bubble it might be air that's been trapped when the tank was setup and working its way to the surface.
     
  7. Wolfenrook

    Wolfenrook Member

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    336
    Location:
    West Midlands UK
    A few bubbles forming is perfectly normal in a substrate anyway, even in a nice aerobic bed you will get CO2 bubbles forming from the bacteria breaking wastes down. It's if the tank starts smelling of rotten eggs, or you get large, abnormal pH drops that it's time to worry as as Clive said this means that hydrogen sulphide is been given off, which means that your substrate bed has become anaerobic.

    Ade
     
  8. willjones

    willjones Member

    Messages:
    47
    Water has a hint of rotten eggs. Worried!
    The only thing I can think of is that when I'm moved some plants, I haven't necessarily pulled out the old roots. Perhaps these are now decaying anaerobically?
     
  9. nickyc

    nickyc Member

    Messages:
    208
    Location:
    Nottingham
    I've got a chopstick I use to prod about between the plants in the areas of the substrate that are densely planted. Little bubbles get released. I do notice the difference in the size of the bubbles if I leave it a while though. :wideyed:
     
  10. JamesM

    JamesM Member

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    The BIG End, South Wales
  11. Wolfenrook

    Wolfenrook Member

    Messages:
    336
    Location:
    West Midlands UK
    Any anaerobic activity in the substrate usually means that there just isn't enough water movement/disturbance in the substrate.

    If you pH isn't too low then as indicated malaysian trumpet snails are good. Other than this giving your gravel a poke during water changes can help a bit, as nickyc suggested.

    I would suggest a few more regular water changes to reduce the amount of sulphuric acid/hydrogen sulphide gas in the water column (take care that the pH doesn't go back up too quickly though), and some gravel poking is perhaps on the cards.

    Oh, and I find that good flow in the water column itself helps to increase the oxygen rich water going into the substrate, purely by preventing dead spots of oxygen poor water building up at the substrate surface, as if this is all there is there then this is what is going to pass through the substrate in convection currents etc. This is why I like to position a small internal filter low down in the tank pointing towards the front from the back. I get bubbles in my substrate, but no rotten eggs smell or drop in pH.

    Ade
     
  12. SuperColey1

    SuperColey1 Member

    Messages:
    2,677
    Location:
    Lincoln UK
    It shouldn't be a problem with leaving old roots in the substrate. Tropica actually suggest cutting plants at their crown and leaving the roots to decay, although I don't because I find that it tends to grow again.
    I think if they suggest it then it shouldn't cause problems.

    As per above I think you may either be less heavily planted than you thought ot your plants aren't growing too well.

    I get large bubbles that come up in certain areas but thats most likely because I have many heavy root feeders which will cause it. I also have MTS and plecs/Rams that love to dig away.

    Andy
     
  13. willjones

    willjones Member

    Messages:
    47
    Thanks for the replies and the suggestions.
    I forgot to add that I have checked the pH and it is not that low around 6.9.
    The KH is about 3, and CO2 is about 10 so I don't think the pH is abnormally low.
    Still getting a whiff of rotten eggs when I do water changes but bubbles seem to have slowed down and fish seem ok at the moment, although I did lose a few cardinals a week ago. :(
    The aquarium is quite densely planted and I have quite a few snails that roam around eating algae, but I don't think they're the type that dig up the substrate.
    I've just started adding nitrate and phosphate fertiliser to the tank, so I'm hoping that will improve the health of the plants and the aquarium (some of the plants were quite nutrient deficient i think). If possible I want to try and avoid emptying the tank and rewashing the substrate.
    The only other thing I was thinking of was whether a substrate heater would have avoided this problem, although they don't seem that popular on this forum.
    Thanks for your thoughts, will
     
  14. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

    Messages:
    8,952
    Location:
    Chicago, USA
    Hi Will,
    I don't think substrate heaters would have helped. As I tried to explain before your problem is lack of oxygen in the substrate. Substrate heaters will not address this fundamental problem. As you noted, starving plants are incapable of delivering sufficient oxygen to the sediment. In the absence of O2 bacteria will use other available chemicals such as sulfur from sulfate (SO4) to extract the nitrogen from the ammonia in the sediment. This is why one end product of anaerobic nitrification is Hydrogen Sulphide gas (H2S) which is the rotten egg smell, instead of nitrate. Consider the preferred nitrogen cycle pathway: NH4->NO2->NO3 There is no way this can happen with insufficient O. Increased CO2 and nutrients delivers O2 to the roots and in this way supports the proper (or desirable) bacterial metabolism.

    Many people view plants as just passive lumps of coal that just sit there looking pretty. In fact, just the opposite is true. Plants have voracious appetites and actively change their environment to suit their needs. If the soil is alkaline they attempt to acidify it. They remove inorganic chemicals from the environment, rearrange those molecules and redistribute the molecules in a organic form (such as sugars) that feeds and nurtures the favorable bacteria with which they have symbiotic relationships.

    Were you aware that almost all of the oxygen in our atmosphere was put there by plants only? And of course they remove CO2 from the atmosphere as well. I saw a recent estimate that the worldwide yearly CO2 consumption by plants was on the order to 120 gigatons - thats 120,000,000,000 Tons of CO2. Incredible... :wideyed:

    There is no need for chopsticks, powerheads or the introduction of disgusting vermin snails. Just feed your plants mate, and give them plenty of CO2 and they will transform the ecology of the sediment and the tank. To accelerate the process add plants with extensive root systems such as crypts and swords. The root systems act as a plumbing network for the redistribution of chemicals and conditioning of the sediment.

    Cheers,
     
  15. willjones

    willjones Member

    Messages:
    47
    Ok, thanks Ceg, I'm listening to the advice given, TPN+ arrived three days ago and just started dosing the aquarium.
    I think there's a fair bit of conflicting advice out there for the beginner, so I'm gradually figuring out who know's what they're talking about! I contacted a few of my LFS's and none of them sold aquarium plant fertiliser containing nitrogen or phosphorus.
    Your explanation makes sense to me, so hopefully things will improve if I get the hang of fertilising the plants.
    I think the tank is starting to look better already actually, when the plants which have turned white have turned green again I'll post some pictures!
     
  16. willjones

    willjones Member

    Messages:
    47
    Have been dosing TPN+ for the last two weeks and plants are looking better in general. My question is how much TPN+ should I go for?
    I do 40% water changes every 1-2 weeks. I have 2 x 40W T8 tubes on 10 hours a day for a 200L aquarium. CO2 is injected and dropchecker is green colour using 4dKH water.
    So far I have been putting 3mls in every 3 days or so. Thought I'd start small and build it up, thinking that my lighting levels aren't that high. Any thoughts on whether this is a sensible approach?
     
  17. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

    Messages:
    8,952
    Location:
    Chicago, USA
    My philosophy is to start high and lower it from there. What is the point of starting low? That just means slightly less starvation. If your plants are starving then they need triage not a band aid. You need to discover how much better condition the plants can get in and then back off from there. I'd dose 15 ml daily, but then I'm a fanatic :D

    Cheers,
     

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