# Water perfectly clear but turned dark green?



## DogTailRed2 (23 Sep 2021)

I have a strange problem with my 450 litre aquarium.
This aquarium has always been clear but recently had a complete breakdown, substrate change, filter upgrades etc.
Six months down the line the water in the aquarium has developed a dark green tint. I have no algae problems in the tank.
No blanket weed. No string algae. I don't even suffer algae on the glass. The tank is furnished entirely with plastic plants (sorry UKAPS  ).
My water parms are Ammonia 0. Nitrite 0. Nitrate 0.5. Phosphate .5. Ph 7 - 7.5. I also tested for copper contamination just in case which is 0.
I perform a 20% water change every week.
Tank is heavily stocked with a mix of Clown Loach. Ancistrous. Some Doras. Barbs. Fish are happy and healthy. Some of the Clowns and Loaches are 16+ years old.
I run Nitra Guard to keep the Nitrates low.

I also changed over time both filters. An FX6 and an Oase 800 Thermo. Both are using Biohome Ultimate. The Oase has a UV clarifier.
When maturing the filters (I ran an old filter while I added each new filter) I added Aqua Bio Balls. These came free with the media.

I have a single Juwel Helialux LED which cycles from 8am to 10pm, sunrise to sunset. It runs fully on between 10 and 5:30 pm.

Things I have tried to cure this problem;
1) Placed a quantity of water in the dark. Three days down the line no apparent change.
2) Adjusted the light profile to have just four hours light to no effect.
3) Added the UV. After four days no apparent change.
4) Trying Blue Exit in some jars to see if that fixes the issue. Two days in no apparent change.
5) tried carbon no effect.

I'm going to try Purigen and Phosgard as a last resort.

Any suggestions on how to fix this issue and how to determine what it is (Bacteria, Algae, something else) ?

Regards,

Ted.

p.s. The images show the affected water left and water from my 260 litre aquarium right. The 260 litre tank has exactly the same setup as the 450 except it doesn't use BioHome Ultimate but just has sponges and Matrix. It even uses the same Juwel LEDs and light profiles. This tank has same parms except higher Phosphates and 40ppm Nitrates. Again fish are happy and healthy.


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## PARAGUAY (23 Sep 2021)

Maybe its the lighting intensity thats the problem. Lighting to high with a long photoperiod. I wouldnt do anything dramatic additives ,chemicals and just stick to several regular water changes lower lighting intensity. Just wondering whats your reason for nitrate removal?Purigen though may help add some fast growing (even float them) fast growing oxenegenating stem plants


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## erwin123 (23 Sep 2021)

DogTailRed2 said:


> The tank is furnished entirely with plastic plants (sorry UKAPS  ).
> 
> 
> Things I have tried to cure this problem;
> ...



UV is very effective in clearing up the algae that turns water green. If UV has no effect, its not algae?

I've never kept plastic plants before, but do they contain chemicals that might leak into the water?


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## DogTailRed2 (23 Sep 2021)

erwin123 said:


> UV is very effective in clearing up the algae that turns water green. If UV has no effect, its not algae?
> 
> I've never kept plastic plants before, but do they contain chemicals that might leak into the water?


I use the same plastic plants in both my aquariums. They are designed for aquarium use so hopefully not.
I tried carbon which should remove contaminants to no effect.
I would expect the plants to change colour if they were releasing dye into the water?
I've no idea really or any way to prove it.


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## DogTailRed2 (23 Sep 2021)

PARAGUAY said:


> Maybe its the lighting intensity thats the problem. Lighting to high with a long photoperiod. I wouldnt do anything dramatic additives ,chemicals and just stick to several regular water changes lower lighting intensity. Just wondering whats your reason for nitrate removal?Purigen though may help add some fast growing (even float them) fast growing oxenegenating stem plants


Reason for nitrate removal. To have low nitrates.
I may try lowering the light profile again. Any suggestions on a time frame? My sample water which is in permanant dark has not changed in three days.


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## PARAGUAY (23 Sep 2021)

If your tanks heavily stocked your water changes and filter maintenance may need looking at. Water changes should help with reducing nitrate. If we are looking at green algae and no live plants then reducing light intensity and reducing your photoperiod by several hours


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## DogTailRed2 (23 Sep 2021)

PARAGUAY said:


> If your tanks heavily stocked your water changes and filter maintenance may need looking at. Water changes should help with reducing nitrate. If we are looking at green algae and no live plants then reducing light intensity and reducing your photoperiod by several hours


I do 20% per week water change and my Nitrates are .5ppm.
I may try changing the light profile. Will this kill Cyanobacteria?


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## Gorillastomp (23 Sep 2021)

Is your water opaque or crystal clear ? Usually algae in suspension makes water opaque.

From what you have tried etc, i tend to think something is leeching coloration in the water.


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## DogTailRed2 (23 Sep 2021)

Gorillastomp said:


> Is your water opaque or crystal clear ? Usually algae in suspension makes water opaque.
> 
> From what you have tried etc, i tend to think something is leeching coloration in the water.


The water is crystal clear. Like you put die in the water.
One thing I did today was replace a broken light unit. I have two light units on my 450. One was broken, disconnected and I was just using it plug the hole in the lids.
Today I replaced that light unit as I was concerned the old unit was filling with moisture and leaching something into the tank. I doubt that was the case (some green water did run out of the unit when I removed it) as the fish are fine. Anyway that's one more thing elliminated. It's possible but again dubious.
So what could be leaching colour into the tank?
Plastic plants? Doubtful. Good branded plants designed for aquarium and plastic is pretty inert. I aslo use similar plants in my other tank.
Substrate? Black crushed volcanic rock. Same as other tank. Again no.
Structured background? Been in the tank for 16 years so I doubt it. No.
Bogwood? That would leach tanins and I doubt there are any left having been in the aquarium for many years.
Filter media? I use Biohome Ultimate and Sponges. Sponges are Black, Blue and Orange. Never seen any colour loss from the pads and as these are designed for aquarium use I doubt it.
Airstones? Again good brand so I doubt it.


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## MichaelJ (23 Sep 2021)

Sounds (and looks) like something is leaching into the water column if it is still crystal clear (green algae would cloud it up in my experience).... Purigen will likely help but slowly, and so will big WC's obviously, but better find the source of the leach first...  Otherwise, if it is indeed some sort of green algae UV light will likely take care of it.
Cheers,
Michael


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## DogTailRed2 (23 Sep 2021)

Could it be Cyanobacteria? Can cyano tint water?


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## GHNelson (23 Sep 2021)

No not as far as I'm aware!
Look under Green Water....in the Link


			James' Planted Tank - Algae Guide


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## X3NiTH (23 Sep 2021)

When did you last replace the UV bulb, if it was over a year ago it’ll be defunct and you need a replacement bulb, if the bulb is less than a year old and it’s not clearing the water then I would slow the flow down from it so there is a larger exposure time of the water to UV, if this doesn’t clear the water then I suggest it’s some form of dye. I would be doing back to back 50% water changes to reset the whole system and clear the water, remineralising where necessary. There are other steps you can take to clear the water if it is a dye but none are as unreactive and passive as a waterchange.


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## DogTailRed2 (23 Sep 2021)

X3NiTH said:


> When did you last replace the UV bulb, if it was over a year ago it’ll be defunct and you need a replacement bulb, if the bulb is less than a year old and it’s not clearing the water then I would slow the flow down from it so there is a larger exposure time of the water to UV, if this doesn’t clear the water then I suggest it’s some form of dye. I would be doing back to back 50% water changes to reset the whole system and clear the water, remineralising where necessary. There are other steps you can take to clear the water if it is a dye but none are as unreactive and passive as a waterchange.


The UV has only been running 6 days when I purchased it


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## X3NiTH (23 Sep 2021)

Regarding the light unit that was broken and green water came out, was it significantly greener? If it has been there long enough has there’s been corrosion of metals inside the light unit if so then there is the possibility of metals entering the water column and staining it if in significant ppm.
Wiring usually contains copper so here are the possible colours from various compounds of copper.







A – Copper metal. Copper metal is a reddish brown solid.
B – Copper(II) carbonate is a green solid/powder.
C – Copper(II) sulfate/nitrate/chloride. These compounds can exist as blue solutions or crystals.
D – Copper(II) oxide is a black solid.
E – Copper(II) hydroxide is a blue precipitate.

Cyanobacteria usually likes to settle and form mats rather than stay suspended in the water column, UV (if functioning correctly) would be taking care of the water column algae so the only place for it is on a surface within the tank.

If you are able to discount both of these then you are left with a dye.

Waterchanges will determine whether it’s a Temporary source of contamination or a Persistent one.


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## GHNelson (23 Sep 2021)

You could try using JBL SymecMicro 




hoggie
​


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## DogTailRed2 (24 Sep 2021)

I've tested for copper which reads zero.
I'm running an experiment with Blue Exit in two jugs. One without treatment and one with, both containing green aquarium water.
Three days in the the treated water is turning cloudy.
My control sample (a wine glass containing aquarium water) placed in a dark cupboard seems to be turning paler.
Time will tell if either of these tests proves positive or not.


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## DogTailRed2 (24 Sep 2021)

As to Symec Micro. I may try this if Purigen, PhosGuard and Blue Exit are all negative.


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## DogTailRed2 (24 Sep 2021)

Any thoughts as to weather adding Aqua Bio Balls could cause some strange bio or algae outbreak?
I added these when I change media about three months ago.
I have since remoaved any remants of the balls just in case.


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## DogTailRed2 (24 Sep 2021)

If this was a contaminant or dye what's the best method to remove?
I ran carbon for a week to no effect.


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## Gorillastomp (25 Sep 2021)

Best is to do a mssive water change like 80% plus 2 to 3 time a weeks until your water is back to normal color. But if you do jot find what cause the dye it may comeback.


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## DogTailRed2 (26 Sep 2021)

With the damaged light unit replaced and after examining the tank and filters I do not believe the green tint is a contaminant.
It's going to be either algae or bacteria.
UV isn't having any effect and as nutrients are low to zero also rules out algae.
Cyanobacteria can live in zero nitrate and in some cases zero light conditions (true but rare) I'm going for a cyano bacteria problem.
Conducting tests using two jugs of water shows Blue Exit turns the water cloudy when treated after five days so it's having an effect on something.
So here's the plan for the next 15 days.
Nutrients and Phosphates have been reduced to zero or near enougth.
I will remove the purigen and phosguard. Start a five day treatment with Blue Exit and then monitor for 10 days without water changes.
If this works then use Red Sea Reef Grade Carbon to remove any floating contaminants after which we replace the purigen.


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## Andy Pierce (27 Sep 2021)

You could try pulling out all your plastic plants, doing a water change and seeing if that clears it up.  Sounds to me like one of your (presumably green) plastic plants is photodegrading now that it's been in the tank under lighting for a while and is leaching out material.  Bacteria isn't green and algae wouldn't be clear and in any event your UV light would sort that out if that were the problem and the light is working as designed.


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## DogTailRed2 (27 Sep 2021)

Andy Pierce said:


> You could try pulling out all your plastic plants, doing a water change and seeing if that clears it up.  Sounds to me like one of your (presumably green) plastic plants is photodegrading now that it's been in the tank under lighting for a while and is leaching out material.  Bacteria isn't green and algae wouldn't be clear and in any event your UV light would sort that out if that were the problem and the light is working as designed.


Pulling out the plants would be an option of last resort. But I'll consider it if my tests prove negative.
Cynaobacteria uses algae for phtosynthesis within it's body for food so can develop a green colour.


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## DogTailRed2 (30 Sep 2021)

Day 7 of static testing. Day 5 of aquarium treatment.

My static water test using Blue Exit showed that at day five the treated water turned cloudy. The untreated water stayed the same.
After day 7 I ran the treated water through RedSea Marine Quality Carbon. After half an hour the water has gone clear with just a hint of green. The clarity of the water has improved 100%.
I am now treating my aqaurium with Blue Exit. I'll let the treatment run for the full 15 days without water changes. At day five there is slight clouding but no change in colour.
After 15 days I will perform a 30% water change and then run RedSea Carbon.
I tested the filter sponges in my FX6 for dye transfer but can find none. I'm also not seeing any change in colour from the plastic plants (removal is too destructive for the fish at this time).
Jury is still out on what is causing this but at least we have a soloution.
Next test will be to run the untreated test sample through carbon to see if it removes the colour.


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## DogTailRed2 (15 Oct 2021)

I ran the untreated water through the carbon and it did remove the colour albeit slower.
Ran Blue Exit for 14 days with no noticeable change in colour although water did get a fraction cloudier.
Added 1000ml of Redsea Marine Spec Carbon in both (half and half) filters and performed a 25% water change over three days.
One filter started to block and noticed what looked like a green algae blocking the sponges.
This is the result.
Water still has a slight tinge to it so I may replace the carbon this weekend in case the Blue Exit and Bacteria / Algae has blocked it.
Parameters are PH 7.6. High PH 7.5. Amonia 0. Nitrite 0. Nitrate 20ppm. I suspect the nitrates have increased because of the water changes. My tap water has 25ppm. My Nitrates are normally 0ppm.
Jury is still out on what has caused this. Lets see if it goes completely clear or comes back after treatment?


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## foxfish (15 Oct 2021)

What a horrible experience, nice to see an improvement ….


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## Wolf6 (15 Oct 2021)

Have you tried removing the plastic plants yet? You said it would be last resort but it sounds like you tried everything else.


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## DogTailRed2 (25 Oct 2021)

Wolf6 said:


> Have you tried removing the plastic plants yet? You said it would be last resort but it sounds like you tried everything else.


No I never removed the plants. The tank is now clear but I am still running carbon. Once the carbon is removed (I'm not intending to use carbon permanantly) I'll wait to see if the green returns. If it does I'll look at the filter sponges then the plants. Why look at the plants last? Well it's going to be quite destructive to the tank to remove them and I'm still not convinced plastic could impart such a colour change. But we will see .


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## DogTailRed2 (25 Oct 2021)

foxfish said:


> What a horrible experience, nice to see an improvement ….


Yes it was. Fortunately it wasn't harmful to the fish. I'm still not convinced what the problem was (and trawling the internet still none the wiser) but my hunch is that the bio balls that shipped with my media (they were pond bio balls but I doubt they would be much different from tropical) caused a spike in nutrients that caused an unusual strain of bacteria that neither resulted in a bloom or caused algae problems. Possibly fueled by the fact I have almost zero nitrate.


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## DogTailRed2 (25 Nov 2021)

Time for an update as it's been two months since I removed the green colour.
Have been running without carbon now for two weeks and there is no sign of the green colour returning.
I believe my problem was due to adding bio balls (the bio balls I was supplied with my media was for pond use but I'm not sure they are any different to aquarium use?) and having very low to zero nitrate.
Best possible cause was a type of blue green algae that survives in low light, low nitrate water. The bio balls perhaps introduced or fueld the algae. Too much biology?
Cure was dosing with Blue Exit at double dose for 14 days after which colour was removed using carbon.
I never removed the plastic plants.
I will say the RedSea Reef Spec carbon is awesome.


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## DogTailRed2 (3 Jan 2022)

Final update.
Definitely a strange form of blue green bacteria that feeds on zero nitrate and zero light level conditions.
Caused I believe by addition of bio balls for some reason.
Blue exit dosed at double for 14 days fixed it.


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