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Water perfectly clear but turned dark green?

DogTailRed2

Member
Joined
23 Sep 2021
Messages
70
Location
UK
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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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
 
The tank is furnished entirely with plastic plants (sorry UKAPS :) ).


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.

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?
 
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.
 
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.
 
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
 
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?
 
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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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.
 
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
 
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.

:)
 
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 :)
 
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.



D64EB047-C759-43D0-A680-B893B087C4B1.jpeg


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.

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