Green Dust

[W Churchill]

I have what I can only describe as a green dust on the surface of the water. The odd thing is I have a marisys filter which takes water from the surface rather than conventional filters which take it from, well, elsewhere, I would have thought this would scoop such stuff up fairly quickly, so it appears to being produced/supplied quite quickly or recycled which I wouldn't have thought possible.

Any ideas.

 

[cbrownfish]

What are you using for circulation? How much flow altogether? The surface of the water should be somewhat turbulent in order to keep organics suspended in the water column where your skimmer/filtration can get to it. If you have a film or similar on top of the water, it is typically some form of dissolved organics A.K.A. poop, pee pee, food particles, etc.

The "green dust" description sounds slightly out of the ordinary to me and makes me wonder if you have anything else in the vicinity that is getting into the tank.

 

[cbrownfish]

For reference, here is what the surface of the water in my tank looks like --

 

[W Churchill]

What are you using for circulation? How much flow altogether? The surface of the water should be somewhat turbulent in order to keep organics suspended in the water column where your skimmer/filtration can get to it. If you have a film or similar on top of the water, it is typically some form of dissolved organics A.K.A. poop, pee pee, food particles, etc.

The "green dust" description sounds slightly out of the ordinary to me and makes me wonder if you have anything else in the vicinity that is getting into the tank.

My tank is 175 ltrs, I have 4 powerheads rated at 1,200 ltr/h, 1 x marisys filter (2,600 ltr/h) and 2 x canister filters (1,250 and 2,250 ltrs/h)

Its the top tank HERE

 

[W Churchill]

For reference, here is what the surface of the water in my tank looks like --

To me my surface doesn't look too much different, it may not be quite as turbulent as yours though. Forgive the lighting it's in the moonlight phase at the moment.

 

[cbrownfish]

The key is that the entire surface is being agitated to some degree and it appears that you have achieved that. In many reef tanks, overflows are used to carry water to a sump and the surface is skimmed constantly. A sump also allows you to push a large volume of water through the tank, so the surface is skimmed quite effectively. However, sounds like your filter is more or less handling that function. More agitation could help get more of the debris/dust to your filter. Is the "dust" something that you can take out and examine with a magnifying glass? Is it slimy or coarse? Do the individual particles absorb water or are they floating? Is it on the entire surface or just in certain areas?

My only guess would be some sort of algae bloom or contaminant that is a bit buoyant and it is somehow staying suspended on the surface. I have seen Cyanobacteria form a film at the surface of a low flow tank but your description does not match Cyano IMO.

 

[W Churchill]

Oh my lord, I feel very silly and very worried.

My protein skimmer was blocked, I didn't notice anything on the water last night - but still. I'm guessing it wasn't just a case of it not working (which might be the case for a while), but likely loosening some of the crud around the top and depositing it back into the tank (which might just of started happening). I've just checked by Nitrite and it's perhaps a little over 0.02 mg/l but not 0.05 mg/l. (was OK on Thursday)

How long could it be before the situation is restored, should I be doing anything else, my immediate thought is not to clean my filters out but is that the wrong thing to assume, I'm actually due to change my Carbon tomorrow, should I put it off and leave the filters alone.

 

[cbrownfish]

Glad you figured it out! I'd be surprised if the lack of skimming for a few days would create a nitrite reading, especially in an established tank. Unless, of course, something has damaged your biofilter. If you are concerned that crusty deposits or sludge from the skimmer has gone back into the tank, then I would do a water change and replace carbon proactively.

 

[W Churchill]

Glad you figured it out! I'd be surprised if the lack of skimming for a few days would create a nitrite reading, especially in an established tank. Unless, of course, something has damaged your biofilter. If you are concerned that crusty deposits or sludge from the skimmer has gone back into the tank, then I would do a water change and replace carbon proactively.

Well I did another test earlier today only 10 hours after correcting the problem and my nitrate was back to zero, but you may well be right about the lack of skimming not causing it, I did have a fish die on me yesterday, it died in the night so it could have been anything up to 12 hours before it got removed.