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Strange Grey/smoky Algae Growing On Rocks And Glass?


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Hello all,

After a long break from this forum, I am not sure what happened to my log on and history. I had to start from scratch with registration.

I have a problem that I could use some help with. A week ago, about 1 week after a water change on my 260ltr 6' victorian tank. A Grey/Smokey type algae started growing rapidly on the glass and rocks etc.. This stuff is Not stringy but is very slimey, and I find forms into clear globs in the pipes of the filters and blocks the filters very quickly. I was running a 2217 Ehiem (1000l/hr) which I have just given a really good clean out. I have also Just added a second Eheim (600l/hr) to boost filtration. The PH is stable but I found Amonia levels very high. I did another 3/4 water change yesterday, followed by the filter clean out. I have added malafix and a good dose of salts, removed all rocks and give it a really good vacuume out, plus cleaned all glass.

Lighting is off and the fish have not been fed for 3 days.

I have looked at all types of algae online but cant find anything like this.

2 years ago I had a simular outbreak while on holidays with a house sitter looking after my fish, this turned fatal and I lost all fish from that one. After a big cleanout then, all has been fine.

Nothing different has been added

Water changes done as per usual, good quality liquid water conditioner used and water sits for 24hrs in a 200ltr plastic drum before being added.

No sick fish.. just stressed at the moment.... they looked very distressed 2 days ago. This tank is very populated, up to 40 maybe, as they keep breeding, but is managed well with filtration, UV steriliser, and regular water changes. I have been trying to get rid of some fish, but as I live in a regional part of the North west, this is proving hard.

Nitrite - 0.8 - 1.6 mg/l

Nitrate 15 - 20 mg/l

Ph 7.8

Ammonia 2.4 mg/l ... 0.08 ppm

Remembering i have done two really big water changes to in a week (Drastic I know!!) and added one brand new Eheim 2236 filter and really cleaned out my other 2217 Eheim. I have also added (last night) a dose of Biological booster to help get the filters online faster.

Has anyone had anything like this and how can i beat it??

IPB Image

IPB Image

IPB Image

Looking very bare right now, These fish were sold as Haplochromis sp. (Flameback)

but looking at this site (link below) I think they are Haplochromis sp. Mbipia lutea. The photo is a dead ringer for mine.


Cheers Damon

Edited by Damon
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A Grey/Smokey type algae started growing rapidly on the glass and rocks etc.. This stuff is Not stringy but is very slimey, and I find forms into clear globs in the pipes of the filters and blocks the filters very quickly

You mention the above as though there is some sort of growth, but when I look at your photos I see no evidence of this. The only thing I can ascertain from the photos is that the water looks a bit cloudy as with what happens with a bacterial bloom which is no great issue.

Good job with the details provided and photos by the way.

A standard cycled tank should have NO ammonia, so you’re right being concerned about the fact you have an ammonia reading. Be aware of the issues of large water changes that you are doing (and I see that you are), but dependant on the water change water matching you existing fish tank water, exporting the ammonia may be preferable than doing a standard size water change.

The question I think that needs to be answered is WHY DO YOU HAVE AN AMMONIA READING? You mention that you have been cleaning out your filters, how have you been treating your biological section? Do you have one? You sound like you know what you are doing, but perhaps increasing your biological section may be a path to follow.

You said that you are using some sort of bacterial starter. This is a good way to go, not only for the new filter you added, but because you have an ammonia reading.

A fully established tank, even with population increases due to breeding should not have any ammonia. That is, as I have said if you have an ammonia reading, there will be a reason for this. Track this down and I expect you will sort out your ammonia problem. It may be as simple as needing more filtration, or proper cleaning.

The only explanation I could give to your description is a bio-film. Some of my tanks get it on the front glass where I clean it off. Other tanks, side by side, don't get it. If it is a bio film, just add it to your cleaning schedule (including running a pipe cleaner through your tubing.

I see no benifit to removing the rocks as they are a surface area for the bacteria to grow on. Removing them holds the potential to increase your ammonia. Removing the rocks will also disturb territories which could further stress your fish.

Reduce feeding, don't cut it altogether.

Having a 220 drum for water changes is good, but do you do anything to match up the pH? Or is it a similar temperature to the tank when added?

If you have been doing regular maintenance as always, I don't think the issue will be related to what happened when you had the tank looked after while you were away.


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