Green Algae Film On Surface

[andyM]

Hi,

I have a planted tank with pressurised co2 and over-tank lighting. The amount of co2 is correct according to the drop checker and plant growth seems ok (only ok, not great). I have noticed that after about 3-4 days of cleaning the tank I get a thin green algae film on the waters surface, and hadn't paid it much attention until now. My co2 canister ran out, and within a day or so the green film had completely disappeared. Does this mean I have my co2 setting too low or too high? Is the green film a problem, or common when using co2?

Thanks.

 

[RadaR]

Addition of CO2 increases the nutrient demands of the plants. When the CO2 ran out, the demand for nutrients decreased and the algae subsided. Thats one theory. What nutrients are you dosing and how often? At the moment it doesnt sound enough.

 

[Primous]

Hi Andy

What is the size of your tank, ph, ammonia, nitrite, and nitrate. Also how many bubbles per second do you currently run your pressurized co2 at?

 

[andyM]

@ RadaR - Until recently I was dosing with Ferropol (about 50ml) every week after the water change. The last couple of months I have only been able to do the water change every 2 weeks tho, same amount of Ferropol but every 2 weeks. I also have some Ferropol 24h of which I (try and remember) to put in 5 drops every morning. Although I forget quite often lol. The plant growth hasnt changed from when I was adding Ferropol every week with the water change to every 2 weeks now.

@Primous - 4 ft tank, approx 280L and 24" deep, ph=7.8 (ph may be slightly higher than usual as the co2 hasnt been on for a few days) amm=0 nitrIte=0 nitrAte=30 (nitrAte in tap water=15). It was running at about 2 bubbles per second, the drop checker showed this as being just below "ok" dosage. I thought slightly low was probably safer than slightly high.

Cheers

 

[RadaR]

Ferropol doesnt have any macro nutrients which the plants are desperate for since you have been injecting CO2. Macro nutrients are your nitrates, phosphates and potassium.
Your test kit may say you have 30ppm of nitrate in the tank but I can almost asure you that it wont be. The nitrate test kits we hobbyists have are complete garbage and are better off in the bin. Infact most nutrient test kits are awful.
Also when dosing CO2, your water changes would be better suited at atleast one per week. CO2 increases the nutrient demand, thus increases the growth rate. Any increase in growth will also mean an increase in metabollic waste. The water changes are needed to reduce this metabollic waste otherwise it can build up which is harmful and can induce algae.

So, plant of action;
When the CO2 is back up and running, dose an all in one fert that contains macro nutrients (Tropica plant nutrition+ for example).
50% water change per week or 2x25%.

 

[andyM]

I'm off to the LFS today to get a new co2 canister so I will take a look for a different plant nutrient. The Ferropol is almost empty anyway, and so expensive!

I will be going back to weekly water changes after this weekend as I will be getting my weekends back for a while

 

[SO19Firearms]

The Ferropol is almost empty anyway, and so expensive!

You might be lucky to find a proper fert at your LFS unless they do Tropica or an Easylife set - Both expensive also.
You won;t find a cheaper method than making your own! - The planted tank - All in One