# Green Film on Surface



## Terry (5 Nov 2008)

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 Graemeâ€™s recent (FoF) advice about flow and a cloudy water issue.  Iâ€™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.  Iâ€™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 â€“ 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) â€“ 10 hours
	    Recently added 1 x 42 inch T8 40w (Powerglow)	3hrs (1330 â€“ 1630)
EI Dosing as per James Planted Tank Instructions link
 Â½ tsp KNO3 - 3 x per week
	â…› tsp	KH2PO4  - 3 x per week		
	â…› tsp K2SO4 3 x per week
	â…› tsp traces â€“ 3 x per week
50% water changed weekly
(Iâ€™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?


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## PM (5 Nov 2008)

I had similar problems for months, tried everything, then I thought sod it!  And bought a skimmer attatchment for Â£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    I'd say it's been my best my for my tank


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## Themuleous (5 Nov 2008)

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


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## ceg4048 (5 Nov 2008)

Try adding more CO2...

Cheers,


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## Themuleous (5 Nov 2008)

ceg4048 said:
			
		

> Try adding more CO2...



Worth a try, but didn't work for me.

Sam


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## JamesM (5 Nov 2008)

Themuleous said:
			
		

> ceg4048 said:
> 
> 
> 
> ...


Nor me... more flow is what you need


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## PM (5 Nov 2008)

I've said it once... and I'll say it again...

SKIMMER SKIMMER SKIMMER


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## JamesM (5 Nov 2008)

PM said:
			
		

> I've said it once... and I'll say it again...
> 
> SKIMMER SKIMMER SKIMMER


But that doesn't solve the root cause of the problem.


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## PM (5 Nov 2008)

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.


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## Dusko (5 Nov 2008)

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


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## JamesM (5 Nov 2008)

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.


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## PM (5 Nov 2008)

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


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## JamesM (5 Nov 2008)

PM said:
			
		

> JAmesM said:
> 
> 
> 
> ...


Â£80 for that kind of turnover is cool with me


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## ceg4048 (5 Nov 2008)

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,


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## Terry (6 Nov 2008)

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.


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## rudedog (16 Nov 2008)

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?


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## Terry (17 Nov 2008)

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.


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## PM (17 Nov 2008)

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...


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## a1Matt (17 Nov 2008)

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   

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


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## Terry (19 Nov 2008)

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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## Terry (23 Nov 2008)

Okay guys, using your valued advice I've moved the CO2 diffuser slightly so that the flow is not obstructed by the taller plants (Echinodorus 'Ozelot Green').  The spray bar (by trial and error) has been moved slightly higher to agitate the surface a bit more and have had to increase the CO2 slightly to compensate. It's been free of scum now for about four days so fingers crossed it stays this way.  Many thanks for all advice given.


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