Samlin

Hi all,
I am new to this forum, and have come to enjoy it. I have a problem and dont know what to do? I have a 300litre tank with tetra's and Gourami's and plecos etc. Total of 38 fish. I use gravel as a substrate. I have a E-Heim Aquaball Internal Filter 650l/h and a 900l/h gutter filter which i recently converted to an External BioFilter ie. using bio-rings, charcoal and aquarium wool. This problem which i experience started prior to me converting the filter though. I notice some fine black powdery deposits on the internal filter as well lots of it on the plants and on the edges of the leaves. I conducted 3 water changes (10-20%) in the past 3 weeks, but that doesnt seem to help. What is it and what should i do? Concerned...
PS. I have attached a photo of my work in progress tank. I am treating the driftwood which i intend to put in this weekend as well as add more plants. If you look closely, you can see the black stuff on the leaves.

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	DSC00968.JPG (93.3 KB, 31 views)
	DSC00971.JPG (92.8 KB, 31 views)

Shawnie

sounds to me like the carbon wasnt rinsed out all the way before you used it

aquarist48

I agree with Shawnie....especially since it's like a powder.

Tombo

this happend to my friends tank it was because she kept washing the carbon filter instead of replacing, so it started falling apart and coming out the filter.

agabr123

agreed, i'd take your filter media out and dump out the carbon, then rinse the media in used tank water (NOT tap water or any water that hasn't been dechlorinated with a water conditioner) to get the rest of the dust off

Samlin

Thanks to all for your fedback. Embarrased to say, yes, i always rinsed out the carbon and never replaced it. Will replace today and clean out filter media as explained by agabr123. However, another question. How often must this be done. ie replacing the carbon?

aquarist48

You should replace the carbon every 3 weeks.