Green Film on Surface

Terry

Member
Joined
13 Oct 2007
Messages
47
Location
Cowplain, Portsmouth
Hi,
Once again I'm looking to UKaps members for advice...sorry! Forgive me I'm still learning about this great hobby.

Problem: for some reason a film of green algae suddenly appeared last week on the top of the water; only obvious by looking up from beneath the surface. The remainder of the tank water looks very clear thanks to Graeme’s recent (FoF) advice about flow and a cloudy water issue. I’ve done the normal weekly 50 % water change and a couple of 25% water changes but the green layer reappears within a day or so.

Plants look healthy IMLE and no other evidence of algae in the tank.

I recently added an additional T8 to give better lighting but in doing so I suspect the balance of lighting and nutrients have been upset. I’ve switched off the extra T8 for the time being but no immediate improvement as yet.

Tank Details
250 ltrs, L48 x W15 x H20 inches
CO2 injection – Starts 2 hrs prior to lighting ON and off 1 hr before lighting switches off
CO2 drop checker showing green.
Substrate: Flora base topped with fine sand
Filter: EHEIM 2026 Pro II
Lighting: 2 x 42 inch T8 40w (Aquaglow and Powerglow) – 10 hours
Recently added 1 x 42 inch T8 40w (Powerglow) 3hrs (1330 – 1630)
EI Dosing as per James Planted Tank Instructions link
½ tsp KNO3 - 3 x per week
â…› tsp KH2PO4 - 3 x per week
â…› tsp K2SO4 3 x per week
⅛ tsp traces – 3 x per week
50% water changed weekly
(I’ve only been dosing EI for approximately 4 months and have seen much improved growth in plants).

The obvious answer is return to original light settings but are there any other options?
 

PM

Member
Joined
15 Dec 2007
Messages
611
Location
London
I had similar problems for months, tried everything, then I thought sod it! And bought a skimmer attatchment for £3 off ebay (the same one that aquaessentials sell), now I skim the surface through the night, ensureing that the surface is crystal clear all day :D I'd say it's been my best my for my tank
 

Themuleous

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6 Jul 2007
Messages
4,124
Location
Aston, Oxfordshire
I have or have had this in several of my tanks. Apart from getting the skimmer as suggested, the only way I've found of properly getting rid of it is to position the top filter outlet so the water breaks the surface. Just like with the oily film, this seems to force the green film under water, where I assume the filter filters it out. It seems to take around a week to get it all and it does come back soemtimes. But repeated 'treatments' like this have managed to eradicate it from some of my tanks.

It is a sod, I give you that. A ugly looking too!

Sam
 

PM

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15 Dec 2007
Messages
611
Location
London
I've said it once... and I'll say it again...

SKIMMER SKIMMER SKIMMER :rolleyes:
 

PM

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15 Dec 2007
Messages
611
Location
London
Maybe so, but it gets rid of it.

I get it in my tank and have more than 10x turnover filter.

If you don't have LOADS of surface movement when you have high light, you are gonna get it.
 

Dusko

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21 Aug 2008
Messages
47
Location
Denmark
The root problem is the insufficient Eheim pump which circulates 250 gph (approx 950 lph) :)
Your tank is 250 litres and should circulate at least 1500 lph or more (I vote for more ;) )
I had that problem in several tanks and each time I have had weak pumps and very little or none surface agitation.

I would remove all the green film by applying paper towels on it. The paper would suck it in. Once the surface is clean add another spare pump which should be the main surface agitator. It worked well for me and for others.

When it comes to adding more CO2, I did it as well and no difference actually I would get more green film :)
The root problem is low CO2 due to poor water circulation (poor nutrient transport), but could also be any other nutrients (like O2).

Focus on adding another pump and create a strong surface agitation mate.

Regards, Dusko
 

JamesM

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17 Apr 2008
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Location
The BIG End, South Wales
PM said:
Maybe so, but it gets rid of it.

I get it in my tank and have more than 10x turnover filter.

If you don't have LOADS of surface movement when you have high light, you are gonna get it.
I had 10x turnover too, but could only get rid of it with 20x rated turnover.
 

PM

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15 Dec 2007
Messages
611
Location
London
JAmesM said:
I had 10x turnover too, but could only get rid of it with 20x rated turnover.
Precisely.

And that's just ridiculous, if not expensive ;)
 

ceg4048

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11 Jul 2007
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Location
Chicago, USA
Hi,
Having 10X turnover by itself means nothing if the distribution and flow patterns are inefficient or counter-productive. Nutrients and CO2 must be delivered to the leaf surface, so the flow patterns, flow velocity, as well as the nutrient/CO2 concentration content of the water must be sufficiently high to eliminate feeding stress. I can reduce my surface agitation to near zero, have high light and never see it, and I have never used a skimmer. Therefore this postulate can't be valid.

I agree though that in closed systems protein and lipid buildup is inevitable so really it's a matter of degree. If your nutrient/CO2 delivery is poor for the level of lighting then the buildup is chronic, whereas good delivery results in less stress and lower buildup rates easily broken up and kept at bay by surface agitation. The choice is yours but I see no reason whatsoever to advocate the use of surface skimmer when it can be clearly demonstrated to be unnecessary. Getting rid of something while ignoring it's root cause merely hides a fundamental weakness which can later cause more grief.

Cheers,
 

Terry

Member
Joined
13 Oct 2007
Messages
47
Location
Cowplain, Portsmouth
As ever, thanks for the replies. Although using a skimmer initially appears to clear the problem I'd like to find the root cause. There must be some reason why it appeared. :? I'll increase CO2 as much as possible and look at the flow patterns again.
I'll get back to with a progress report.
 

rudedog

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Joined
8 Sep 2008
Messages
13
Terry said:
As ever, thanks for the replies. Although using a skimmer initially appears to clear the problem I'd like to find the root cause. There must be some reason why it appeared. :? I'll increase CO2 as much as possible and look at the flow patterns again.
I'll get back to with a progress report.
Ever since I added pressurised CO2 i've been plagued with surface scum. I have a 180L Juwel tank which runs with both its original internal filter coupled with an exteral eheim 2324 so I'd be really surprised if this problem has anything to do with filtration. I use EI dosing and do weekly 50% water changes.

10 days ago, I took my tank down to swich substrate from plain gravel to Eco Complete and surprisingly, the surface of my tank has been crystal clear since then. I've always had very soft water (Gh&Kh both ~3) and i've noticed the Eco has pushed my Gh up a fair bit. Perhaps 10 days is too short a time to make comparisons but is it possible the extent of surface scum could be related to hardness?
 

Terry

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13 Oct 2007
Messages
47
Location
Cowplain, Portsmouth
Rudedog - Interesting thought regarding the hardness.
CO2 is lime green and not sure I can increase any further. Flow now appears to be fine but scum reappears within two or three days of a water change. I'll test for GH/KH tonight.
 

PM

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My tap water is very hard, and I use eco-complete, but I still get surface scum unless I use my skimmer attachment every couple of days...
 

a1Matt

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10 Mar 2008
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Location
Bromley
rudedog said:
10 days ago, I took my tank down to swich substrate from plain gravel to Eco Complete and surprisingly, the surface of my tank has been crystal clear since then.

From my own experience I know that when I get surface scum if I clean my filter it generally clears it. I suspect that it is the increase in flow from a clean filter that does the trick. This supports Duskos theory that flow is key.

It also happens to me if a fish dies and decomposes in the tank. This would imply that my filters bacterial load can't cope and the "short term ammonia overload" results in the surface scum. So maybe your gravel was really dirty and any distrubance of it was adding to the filters workload whereas the eco complete isn't dirty so doesn't add that load.

Or! maybe your plants aren't leaching as much protein as they are getting a good meal out of the substrate now.

or a bit of everything as is often the case :D

These are just ideas to chuck into the pot. I'm not an expert on this.
 

Terry

Member
Joined
13 Oct 2007
Messages
47
Location
Cowplain, Portsmouth
I've tested the GM and KH with the following results: GM 11dH and KH 14dH with PH 7.2. Testing my tap water gives me the same results. Puzzled :? about PH as I thought that would be a little lower given the CO2 injection.
So, I've still not removed the surface scum with the remaining water still crystal clear. Filter is regularly cleaned as are the inlet and outlet tubes. It looks as if I may need to invest in a skimmer although I would still like to find the root cause.

Appreciate everyones advice thus far.
 
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