20 gallon tank, murky green water?

Discussion in 'Aquarium Water' started by kuhliloach85, Aug 10, 2015.

  1. kuhliloach85Valued MemberMember

    Hi folks.

    I have a 20 gallon community tank, with the following inhabitants:

    - Bristlenose pleco (baby)
    - 6 Glowlight tetras
    - 6 Platys

    It's a rather heavily planted tank, and all my plants are doing well. I use a mix of sand and gravel substrate and Flourish root tabs to keep my plants happy. I feed my fish once/day and do not overfeed.

    Over the past few months, my tank has been excellent and I've been keeping up with regular weekly water changes of 25%-50%.

    However, in the past month, I noticed the water getting very murky -- a greenish tint -- even just 1 day after water change. Water readings all show normal -- 0 ammonia, 0 nitrite, 5-10 ppm nitrate.

    I run a Penguin 100 bio-wheel power filter on it -- which processes up to 100 gallons/hour -- last week, I decided to do a large water change and change the filter (I never had changed it before; only rinsed off) -- and still, murky greenish water by day 2.

    The tank doesn't get direct sunlight, isn't overstocked, and isn't overfed - I have no idea what can be causing this green murkiness.

    I just went out and got a power filter that processes 200 gallons/hour -- perhaps the 100 gallons/hour was too small? Will update. Any ideas anyone has to help would be great, too. I'm stumped.

  2. Dom90Fishlore VIPMember

    Yep the 100 GPH was too overrated for a 20g. You'll want at least 8-10x GPH for a HOB.

    Sent from my iPhone using Fish Lore Aquarium Fish Forum
  3. junebugFishlore LegendMember

    Dom90 that rule applies to actual filtration. Since this tank is heavily planted, the filter is actually just providing water movement. I doubt much if any BB are living in the filter media. The plants will be gobbling up ammonia before it ever enters the filter.

    Green water algae is almost always the result of too much light. How long each day are the tank lights on? What spectrum are they? Fluorescent or LED? PAR rating for your tank depth?
  4. kuhliloach85Valued MemberMember

    Thanks! I picked up an Aqueon QuietFlow 30 (200 GPH); will update when I'm home if this solved the issues.
  5. Dom90Fishlore VIPMember

    Correct but you can never have too much filtration so more power to the OP for upgrading the filter.

    Sent from my iPhone using Fish Lore Aquarium Fish Forum
  6. kuhliloach85Valued MemberMember

    Hi there. I run an overhead light that contains 2 fluorescent tubes. It came with the tank - which I purchased from a friend - and I am not sure the PAR/specs of the light itself. The lights are on for about 8-10 hours a day.
  7. junebugFishlore LegendMember

    What kind of fluorescents are they? T5? T8? T5HO? How long are they and/or what brand? Looking up the PAR rating once you know the brand and bulb type shouldn't be too hard.

    Shortening to 6 hours a day will probably help, though. 8-10 hours is a long time for the lights to be on. Adding a liquid carbon to your weekly routine wouldn't be a bad idea either, as your plants would be able to start outcompeting the algae.
  8. DanB80TTSWell Known MemberMember

    I ran into a similar problem a while back, I moved my aquarium to the darkest part of the room away from the windows and any ambient natural lighting (not just direct sunlight). Covered the aquarium and left the lights off for a week or so and continued to dose flourish excel (liquid carbon). That did the trick for me and I haven't had green murky water since. The plants might look a bit bit miserable after a week without any light but they should recover.
  9. kuhliloach85Valued MemberMember

    All right, so here's an update:

    The filter doesn't seem to be the issue, although I feel better having upgraded it to something more appropriate for a 20 gal.

    Now the water is just cloudy looking -- not greenish. I'm chalking this up to some bacteria mini-bloom, although the water parameters all check out. I'll try fasting the fish for a day or so.

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