Why is mold growing under my aquarium lid?

Discussion in 'Freshwater Beginners' started by SofieM, Jul 14, 2014.

  1. SofieMNew MemberMember

    I have a 5 gallon fish tank. Tiny I know. I want to get a 15 gallon when I can.

    My tank has been running for just over 2 months and houses 3 black skirt tetras and 2 ghost shrimp. I'm learning as I go.

    My question is, why is there mold growing on the inside of the lid of my tank? I have a heater which keeps the water at about 77-78 degrees F. I have never done a partial water change yet (I've been reading about how it helps with ammonia levels. I just got a test kit and the ammonia levels read between 0ppm and 0.25ppm.)


    I also have a filter, but it was used prior, and I suspect it may need to be changed.

    I feed the fish through that hole in the image. Is this the food getting stuck and gone moldy? There is also mold on the cord to the blue light I never use.

    I read somewhere this could be calcium deposits if you have hard water. I did use hard tap water, but I also used the proper amount of water conditioner as suggested on the bottle. Or is this mold? Is it toxic? Will it harm my fish? How do I prevent it? Do I need to clean underneath the lid regularly? Is this a sign that there is something wrong in my tank?
  2. Adam55

    Adam55Well Known MemberMember

    It could be mold, but that's not the likely answer. Can you zoom in a little? More than likely, what you have is algae. You'll want to do a water change as soon as you can if it's been two months without one.
  3. Phishphin

    PhishphinWell Known MemberMember

    Are you using test strips or drops to test your water? While the bioload of your 5 gallon isn't huge, you will still want to do partial water changes once a week (maybe 20% of the water). Your profile says you know about the nitrogen cycle, so you will also know that nitrites and nitrates may also cause problems for your fish if left unchecked. Although nitrates are less dangerous than ammonia and nitrites, you still may have quite a build up after two months. PWC are really the only way to manage this effectively. And as far as your filter goes, it houses the majority of your beneficial bacteria that converts the ammonia and nitrites into less deadly nitrates; if you have a cartridge filter and throw it out, you will essentially restart your nitrogen cycle.

    Good luck on the tank upgrade! You may already know this, but you can find some really fantastic deals online. If you do upgrade, I would recommend increasing the black skirt tetras to at least 5; they will be much happier. :)
  4. Sayba

    SaybaWell Known MemberMember

    I sometimes get damp mold on my condensation tray and it's really hard to clean off, but a tighter fitting lid seems to have helped, no idea why, but its worked very well and any new patches growing normally die off.
  5. OP

    SofieMNew MemberMember

    Thanks for all the great tips. Yes I know about the nitrogen cycle, but it's more like I know *of* it rather than that I am an expert with it. I wasn't sure what to put. I am actually just learning.
    Sorry it took a while to get back online. I've cleaned the lid. It looked like some fish food got damp and moldy. If it happens again I can post it.

    My two ghost shrimp died! :( What could be wrong? What is PWC? I have drops to test the water.
    I did a 20% water change yesterday. Today the charts read:
    Ammonia 0ppm
    Nitrite 0ppm
    Nitrate 5.0ppm
    PH 8.2

    Isn't a PH of 8.2 too high for tetras? I think they thrive about a 6.5 or 7. How do I change the PH levels? Could this be why my shrimp died?
    I'm having trouble grasping the concept of PH.
  6. Bob Ellis

    Bob EllisValued MemberMember

    It might not be what it is but that looks a lot like a food flake that sat on the water uneaten.

    Sent from my iPhone using Fish Lore Aquarium Fish Forum

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