This site is supported by the advertisements on it, please disable your AdBlocker so we can continue to provide you with the quality content you expect.
  1. Dismiss Notice
  2. We are after as many aquarium plant images that we can get, doing so will assist us in completing the aquarium plant database.

    https://barrreport.com/threads/aquatic-plant-images-wanted.14374/
    Dismiss Notice

Overloading/Too many fish's effects on plant growth

Discussion in 'Fish for Planted Tanks' started by Tom Barr, Apr 24, 2008.

  1. Tom Barr

    Tom Barr Founder
    Staff Member Administrator

    Joined:
    Jan 23, 2005
    Messages:
    18,676
    Likes Received:
    641
    Local Time:
    6:14 AM
    I noted some possible hypothesis and observations recently when I overloaded a well running 20 Gallon tank with some 50 Cardinals, 30 shrimp, 6 Killis, 24 cories.

    I added another 24 King emperor tetras.

    I allowed the plants to grow up more: poor growth, poor circulation, less CO2.higher pH. Same rate of CO2.
    Less O2.

    I hacked the plants back: more CO2, lower pH, high O2.

    Overall, better growth.

    When I removed the emperors, the next day the tank pearled much more than the last 3 weeks when I added the emperor's.

    The tank haqd been doing well prior to adding these fish and had a max load of the fish load minus the emperor tetras.

    Adding these fish pushed the system too far and caused poor plant growth, some slight melting, slowed growth rates, lower O2.

    The lowering O2 and reduced pearling may be a function of less bacteria and less fish consuming the O2.

    But the plant growth appears better certainly.

    Maybe the reduced NH4 production and the reduced O2 demand are playing dual roles.

    In any event, NH4 and O2 play a large role here in the appearance of the tank.
    And removal of the fish load really produced a dramatic result.

    When plants pearl well, they also might push algae off and help drive bacteria cycling rates much faster(more O2).

    So over loading a tank might be a function of reduced O2 and more NH4 that affects the plants, algae and the fish health, not just NH4 alone.

    Adding NH4 with high O2 might be okay, whereas adding NH4+ low O2 might not.
    Is this due to the available O2 that allows the tank to handle more NH4?
    I have O2 gas, so I might add that to see.

    Amano uses low fish loads, and most scapes do.
    I'm interested in combining high fish and high plant loads together.

    I think you have a lot more play and wiggle room with low fish loads and low NH4, adding more O2 seems to drive the bacteria. but how does it drive plant growth?

    Do higher fish loads and lower O2(adding more NH4 and less O2) increase plant growth? That's what some claim(NH4 is preferred and less O2 produces less photorespiration).

    But I do not see it in any tanks I've done this treatment to.
    If I add some NH4 from salts, then I rarely see it, if I add a lot of NH4, then I do.
    But adding less NH4, combined with less O2, this clearly affects bacteria as well, and perhaps they, rather than the plants, are controlling the NH4.

    If you assume that plants like and prefer NH4, then we should see better, not worse growth(not considering algae blooms) in plants right?

    I did not see that however.
    Good bacteria cycling, higher O2, low to moderate fish stocking rates, then you can likely add some NH4 without too much issue, but at higher levels or with lower O2, or high fish loads............then probably not.

    I'll need to think and look into it more, but it seems that there's a relationship there and adding NH4 to a low fish stocked tank with good plant growth/high O2, may not have much to do with plants as it does with the bacteria.

    Whereas in an overloaded tank, the NH4 and lower O2 might drive this to a poor state.

    High fish loads like this are certainly not good for plants, even with 2-3x a week water changes and nutrients, good CO2 etc. No algae formed doing this, just bad plant health, growth, less pearling, lower O2.

    Regards,
    tom Barr
     
  2. defdac

    defdac Lifetime Members
    Lifetime Member

    Joined:
    Aug 25, 2006
    Messages:
    95
    Likes Received:
    0
    Local Time:
    6:14 AM
    I can't say anything about fish overloading since I've seldom or never done it.

    However, I usually select rather intricate and very dense plant populations where mulm collects and that is very difficult to remove. Before I got really anal with removing mulm I also was very reluctant of removing mulm from my canister filters.

    I had tons of oxygen depleting mulm and quite a bit of POC because I had no shredders.

    All this POC/mulm caused bad pearling despite very high CO2-levels, and rather crappy growth too. The filter media inside the canister seldom smelled the way it should (healthy earthy stream kind of) and it was not the brown mulm color I was used to.

    When I found the Physa snail and introduced it things started to really take of. All of a sudden the POC went away and the filter started to collect some serious amount of healthy smelling mulm. Fluffing out mulm from the plant groups was a breeze - just waving the hand through them and poking around.

    About at the same time I noticed high NO3-levels seemed to inhibit some plants, even ones that are heavy NO3-feeders like M. umbrosum. Mostly woody plants though like A. reineckii and L. glandulosa. L. arcuata to some extent. I have really low KH/GH so I started manipulating Ca/Mg levels like crazy to no avail.

    Before I could dose 5 ppm NO3 3-4 times a week. I backed that to one single 10 ppm dose for the whole week and there it was. The growth. The pearling. I backed the CO2 too and drive a consistent 1 bubble/sec without ever measuring the pH.

    A couple of weeks ago one fish died and I just let it lying around to see if the oxygen-dip and possible NH4-spike would do anything. Sure it did! Some green algae on the glass developed, which I just had to wipe away before the next wc and then all was fine again.

    The whole tank feels extremely stable despite really low dosing and no pH-check whatever. Here it is:
    DefBlog - Akvarieuppdatering

    The NO3 with low KH/GH is wierd stuff though. I have about 2 in KH/GH.
     
  3. Dusko

    Dusko Prolific Poster

    Joined:
    Apr 20, 2006
    Messages:
    68
    Likes Received:
    0
    Local Time:
    6:14 AM
    Emperors probably reduced the O2 levels (fish respiration, fish waste, etc).
    In my case, i didn't over stock with fish, but reduced the O2 in another way;

    In the past, I used to think how still water surface would help keeping CO2 from depletion.
    So, no surface agitation, dosing all nutrients, dosing CO2, 4KH, 7GH, 7.4pH, reduced WC, reduced filter cleaning, small fish normally stocked, 48 gall tank, 1.3w/g, circulation 4x of tank volume (liter per hour), plants pruned not to reach the surface.

    I got algae, and especially the green surface scum/film. I would clean the film as soon it would appear, not to reduce light levels. What is missing? What was causing this problem? The only thing left was reduced O2 levels = less O2 for bacteria + possible NH4 since bacteria had less O2 for NH4 oxidation.
    Plants can uptake NH4, especially at low concentrations, so this should not be the problem.
    What then?

    Plants had enough of CO2 (for low light tank) and nutrients + aqua soil to grow well.
    Soils also reduce O2 (DOC), fish do, bacteria also.
    Low O2 was the only explanation (poor gas exchange).

    What I did is, I introduced another pump 350 l/h which was agitating the surface now, cleaned the existing filter/pump and pointed that 700 l/h pump to the surface also = lots of moderate ripples (but no splashes). Now circulation was 6x of the tank water volume per hour.
    I also reduced CO2. Manually removed all visible algae.

    The result was satisfying, no algae and no film started growing back, crystal clear water, good plant growth.

    Since then, I started looking at O2 (surface agitation, water turn over, clean filters, pruned plants, less fish) with great respect.

    Something we have to cope in Sweden (tap water way too soft) ;)
    And for that reason I will from now on, always mix some (maybe lots) crushed dolomite (faxegrus) with the soil (gravel over it of course).
    Soon I will start one Hi-tech, where I will test this.

    Regards, Dusko
     
  4. defdac

    defdac Lifetime Members
    Lifetime Member

    Joined:
    Aug 25, 2006
    Messages:
    95
    Likes Received:
    0
    Local Time:
    6:14 AM
    BTDT.. You can buy my 25 kg sack of Dolomite 8)
     
  5. Tom Barr

    Tom Barr Founder
    Staff Member Administrator

    Joined:
    Jan 23, 2005
    Messages:
    18,676
    Likes Received:
    641
    Local Time:
    6:14 AM
    Dolomite is good stuff.

    Update on the tanks: after removal of the fish load, but not much else, the tanks all responded very well.

    Clarity was back up, no surface scum, pearling increased substantially, O2 went from 5 to 8ppm on average, no algae, no plant issues, increased fish health/vigor/behavior/feeding.

    It took several days, 1-2 weeks for the tank to bounce back and I did do 2x a week large water changes, but it's a repeat when I did this very carefully with ghost shrimp.

    I also saw the exact same species of algae appear and had very hard water then, now I have very soft water. I can now dose more nutrients and they are getting used up by the plants.

    If you get enough organic material and enough cycling in the sediment, then you essentially now have another source of nutrients.

    So it's no longer just using KNO3.......the ADA As helps to this extent, or you can wait until it builds up, or add things that shred the POC so the bacteria can get at it.

    Amano shrimp, snails etc are good, but there are many smaller things/worms you cannot see that are effective as well.

    But they need O2...............

    One of the main keys here is really rate.
    How fast can the aquarium cycle and process the waste?
    How much decaying biomass is released?
    How effective is the filter, the bioload etc at processing it?
    What is the BOD?



    Regards,
    Tom Barr
     
  6. ceg4048

    ceg4048 Lifetime Charter Member
    Lifetime Member

    Joined:
    Mar 21, 2005
    Messages:
    240
    Likes Received:
    0
    Local Time:
    6:14 AM
    Hi,
    This seems to be corroborated by the 1992 report by your man K. R. Reddy entitled "Nutrient Transformation in Sediments as Influenced by Oxygen Supply" http://wetlands.ifas.ufl.edu/publications/PDF-articles/173.Nutrient%20transformations.pdf

    I had to read it about ten times before I could get a clue but it states clearly that ammonium concentrations decrease rapidly under oxidized conditions. He cites attenuated nitrification as the cause. Under low O2 conditions he reports that ammonium concentrations actually slowly increase.

    This data, as well as your observations of poorer plant health under low O2/high NH4 conditions would also appear to conflict with the arguments which claim NH4-N preference by plants.

    Cheers,
     
  7. Tom Barr

    Tom Barr Founder
    Staff Member Administrator

    Joined:
    Jan 23, 2005
    Messages:
    18,676
    Likes Received:
    641
    Local Time:
    6:14 AM
    It's all about the dose.
    NH4 is used as herbicide FYI, but at lower levels and in the sediments, it's fine.
    On the leaves, it's not.

    You can try this and add liquid concentrated ferts on any terrestrial plant, too much burns the heck out any plant and can kill it.

    My area that I focus on is not "too much or too little" in general terms, but rather what are these rates,dosages, exposure times, concentrations before we see effects on plants, fish, shrimp, bacterial cycling, etc.........

    What are the maximum and min limits and from that, we can assign a risk factor(which is a subjective parameter).

    But the assignment of the risk needs some support.
    Foloks in the hobby often say excess N or excess P.

    That's wothless information.

    We need to know where the N is, where is it coming from, how much and what form is in it.

    We also need to make sure the test we do are independent from the other things like O2, CO2 and other nutrients.

    I do not have nearly enough replications on some test, so I really cannot say with any confidence. But others, I've done several times and can be pretty sure the results are the same as long as I keep the other parameters in good shape, thus independent of the dependent variable of interest.

    Multivariable systems can get hairy, but they are not impossible to work through and see which of the factors are producing the lion's share of the results/response variable.

    The Reddy paper tells you nothing surprising really.
    If you have O2, then you oxidize everything and have high Redox, if not, then things get reduced and generally P and NH4 are far more mobile and likely to move out of the sediment and causes issues in the water column.

    This is how a sediment might sour over time if you over load things in the tank.
    If you deep vaccuum the sediment once every 1-2 years or so, you can prevent that. Also, plant roots pump a lot of O2 down there, more than enough to keep good redox levels and bacterial cycling moving along nicely.

    If you remove a large sword plant from a tank, you will see the redox drop from the sediment and also the NH4/P increase, and less O2 produced overall.
    We'd expect all that too.
    Bacteria alone is not all of it, we need to add the Fish, shrimp, snails, plants and density of the plants root systems into all this.

    Regards,
    Tom Barr
     
Loading...

Share This Page

  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