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Discussion Starter · #1 ·
G'Day,

My tank developed very bad greenwater(GW) the visibility is 2"

Things I tried in sequence:
°I lowered light for 2 weeks to no effect.
°3 Day blackout followed by water change (WC)
°1/2 dose of algaefix
°5 Day blackout, no food or fertilizer from this point followed by a WC and full dose of Algaefix the tank looks clearer visibility 7" but 4 or more dead fish
°3 days later another full dose of algaefix and the GW is back strong with 2" visibility again.

I can't figure this one out. It started right before a 2 month trip I still don't get home for a month (Freind taking care of it). Can anyone please help?
 

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How long has the tank been set up? What type of substrate? What size tank and how many fish?
Only seen this myself with elevated ammonia level's and high light in excess.
Could be friend has fed too much food which may have triggered the condition but am only speculating.
Filter material may be excessively dirty.
Maybe too much organic matter trapped there?
Maybe too much fertilizer added to substrate (see osmocote)
Might try a couple 50 % water changes 12 hours apart and give filter material a good clean in old tank water or dechlorinated water.
Might also run some fresh carbon for a week.
See that only one person is feeding the tank and maybe feed every other day or every two day's for a couple week's.
Last resort for me might be UV sterilizer.
 

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Discussion Starter · #3 ·
180L tank with Mineralised topsoil capped with gravel. The soil started releasing nitrogen has shortly before this started how that I think about it.
Ammonia was always zero when I tested as the problem started before I left and if anything I wasn't feeding enough. I never use soil ferts, and tried fresh carbon. During the first stages I did a couple water changes to no avail and made sure the canister is clean.

My lights were set to 75% when it started, I lowered to 45% which has always been a good medium setting, now it's on 25%. The tank has been set for 2 or 3 months with this substrate and is very plant heavy, all fast stems. The person is definitely not over feeding,a couple pellets every 2 days and I had about 9 tetra sized fish to start plus 6 sucking cats.

I'd love to try a filter clean but this caretaker would have no chance of succeeding without drama, and I can't get UV sadly.
 

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Discussion Starter · #4 ·
So I tried a flocculating agent and that didn't work either. I have told the caretaker to turn the lights back up and resume feeding. I'll just see what survives when I get home in a month.
 

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Solution. Buy a UV Sterilizer. Job done.
Why could you not get UV.
Fleabay has them on the cheap. Work great.
 

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Discussion Starter · #6 ·
I cannot buy one as I am in a remote desert 3,600km from my home. The caretaker of my tank does not have the necessary skills or interest to plumb it inline with my filter without causing a catastrophe. I have been gone a month and it will be another month till I can return to work on the tank. Until then I can get minor things like water changes, light adjustment and chemicals added but that's about it.
 

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Remove the fish to another tank. Take all of the water out. Leave it empty for 2 weeks with no lights.

Fix the problem which are the lights. They're too strong or they were left on way too long.
 

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I cannot buy one as I am in a remote desert 3,600km from my home. The caretaker of my tank does not have the necessary skills or interest to plumb it inline with my filter without causing a catastrophe. I have been gone a month and it will be another month till I can return to work on the tank. Until then I can get minor things like water changes, light adjustment and chemicals added but that's about it.
Ugh. Good reason.

Sent from my VS985 4G using Tapatalk
 

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Add floating plants and let them cover the entire surface. They cut the light and competition the green water algae.

Possible drawback, they cut the light for the plants under as well.
 

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Yes but sounds like the caretaker of his tank is just as likely to put plants in upside down as right side up lol
But worth a shot! Even duckeed they can just dump that in the tank. Be a pain to get rid of later but.....
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Ok, this is a stupid question but if the fish aren't being overfed, and you're not around to see it, is the green water hurting anything? I know it's unsightly, but it's not actually a problem unless you get a huge die off (by trying to kill it for example), is it? Can it get so thick as to actually be a problem for fish?

I'd say let the green water stay green, make sure the filter media is getting rinsed out a bit more regularly since the algae will get filtered out some, and let it be.

My only other question would be if you changed food products prior to the green water appearance, or some other thing like light period.
 

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Some people deliberately keep their water green to grow out fry and such. As long as it's not annoying you, I'd say leave it be. It will probably clear up on its own.

If you really want to get rid of it, get some large-ish floating plants (not duckweed). Water sprite, salvinia, red root floater, and frogbit are excellent for not only blocking light but also removing excess nitrogen.
 
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