Stopping a green water algae increase

[rion_bio]

Context:

• 45p tank size
• medium to high stocking rate (7 ember tetra, 1 golden gourami, 2 cherry barbs) and many ramshorn snails
• 50% of tank floor covered nearly 6 months with well-established, fast-growing stem plants. Hair grass other 50% covering tank floor
• Substrate thin layer clay-based garden soil and topped with double amount of course river and pool filter sand
• plants trimmed ~2 months ago to increase aesthetics
• green water algae started after trim (was issue initially with set up as well but became crystal clear when plants were near surface)
• plants somewhat grown in currently after trim but green water slowly increasing with sub-50% light strength
• no CO2 injection
• Light is Chihiros WRGB II Slim (sub-50%)

My assumptions:

• Fish and snail pop produce more nutrients than what plants can uptake
• Algae bloom is the result

What could the solution(s) be?

• Less light challenging plant and algae nutrient uptake?
• More light in the hope plant growth will use nutrients which might starve algae?
• Other reasons?

 

[dw1305]

Hi all,

• 50% of tank floor covered nearly 6 months with well-established, fast-growing stem plants. Hair grass other 50% covering tank floor

Can we have a picture? An image really is worth a thousand words.

• Substrate thin layer clay-based garden soil and topped with double amount of course river and pool filter sand

Does this mean you aren't adding any other fertiliser?

• plants trimmed ~2 months ago to increase aesthetics

More plant mass is your friend. I don't do aesthetics, so all my tanks are full of plants.

• More light in the hope plant growth will use nutrients which might starve algae?
• Other reasons?

I like a floating plant, it will act as both net curtain and nutrient sink.

Cheers Darrel

 

[Connswater]

green water algae started after trim

Bad luck, the trimming may have been the trigger but I've never had green water in a tropical aquarium in over 50 years running tanks. Normally a pond problem, though as a very young child, certainly younger than 7, when I had, horror of horrors, goldfish in a dastardly bowl, I got green algae stained water, I used to change the water under parental supervision with cold tap water from an upstairs tap, a tap fed from the roof space tank so safe for fish (my dad knew a thing or two), and when a bit older I remember telling my primary school teacher (who I had a childish crush on) that the goldfish tank needed moved, a filter and plants to stop green water, she let me sort it out, I was 10, ref. my primary school teacher, think 'Jo' in Dr Who for a mental picture!

Sunlight is normally the culprit, since mid-February it is strong enough to cause photosynthesis indoors and combined with high or even moderate nutrient loads will create green water, a bottle on the window sill with a pinch of fish food will do this trick. For my goldfish pond, come May, I use a UV filter. I'd add some floating plants and check that the curtains don't need pulled, mornings and evenings tend to be when a tank gets hit by sunlight, causes problems in my tank every year with filament algae, the tank gets hit with sunlight in the morning and the CO2 isn't on, so it gets a bit imbalanced, the problem lasts until the summer, Autumn isn't a problem because by then the light then hitting the tank is when the CO2 is on.

 

[rion_bio]

No additional ferts for months now

BTW, water is mineralised RO but rarely change it merely tops up (and changes do not solve the green water in any case).

TDS currently at: ~100 ppm. Water temps currently coolest since set up.

So what you see below used to be near-solid green murk.

No direct sunlight ever hits the tank. I use the siesta system for CO2 production by having a 4(?) hour period between two 5 hour light on bouts.

That floater is kinda a floating plant indigenous to my country and same sp as tall in back but came out of another tank recently.

 

[Connswater]

Thanks for the picture.

If we rule out sunlight, I suspect you simply don't have enough plants, that perhaps you may have a high Phosphate level and your lighting might be bit too intense for the limited plant mass you have, floating plants would soften the light and help soak up excess nutrients (if they are there). I'd also suggest only 6 hours of total lighting long-term, maybe dropping to just 4 for a week or so. Think of the latter like a cloudy spell in nature. I once shaded a pond with a garden umbrella/parasol to clear green water, took about two weeks. Obviously it was only a reduction in light.

I've used the siesta strategy to balance out CO2, sugar & yeast 24 hour low CO2 injection, otherwise I haven't found it helpful, even on a pure Walstad tank. But for the latter to work well you need really lots of easy plants to start with - hygrophila polysperma, hornwort, egeria, hornwort, vallis etc., and in quantities. And also, I'm big on floating plants, especially until things are really stable - 6 months or so. Good luck and let us all know how you ultimately solve this. South Africa, makes me think temperature might have been an issue but not now and also any comments from me on seasonal variation on light, they would need 'flipped'!