# CO2 induced algae?



## joshd (Oct 16, 2009)

So I added pressurized CO2 to my tank 2 weeks ago. And when I added the CO2 I also increased the photoperiod by 1 hour. This tank has been running since October and doing pretty well. I have been dosing with excel since December. Have had a small amount of a green hair algae but not much. 

I stopped the excel when I got the CO2. I have a piece of driftwood in there that had java moss completely engulfing it. Around the same time as the CO2 addition, I significantly thinned the moss. Now I am having an algae bloom on the driftwood. I am seeing a lot more hair algae and BBA. I have tried to remove the hair algae by hand and have been spot treating the BBA with H2O2. 

But what I am trying to figure out is why the algae all the sudden. Nothing else really seemed to change. I do a 30 to 40 % water change weekly. Does anyone have any thoughts on what the problem might be or have suggestions on the fight? I have included a recent FTS as a bit of reference.

My tanks specs are:
20g tall
rena xp1 filter
36w T5 HO (9 hr photo period)
CO2 - 5lb tank with ceramic diffuser (1 bps)
black sand substrate
dosing - Seachem Flourish and root tabs
flora - hydrocotyle leucocephala
hygro kompact
java moss
marselia minuta (just added)
fauna- 20 harlequin rasbora
2 otos
50+ RCS
1 assassin snail


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## madtundra01 (Jan 27, 2010)

I would say photoperiod. I had some hair algae and bba a while back and I reduced the photoperiod by 1 hour and upped the co2 to 1 1/2 bps. Its almost contained now. What is your co2 level and how many hours per day are your lights on ?


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## joshd (Oct 16, 2009)

madtundra01 said:


> I would say photoperiod. I had some hair algae and bba a while back and I reduced the photoperiod by 1 hour and upped the co2 to 1 1/2 bps. Its almost contained now. What is your co2 level and how many hours per day are your lights on ?


Photoperiod is 9 hrs. I will try going back to 8. My C02 is around 1.2 bps, I can up that just a bit. I don't have a good system for measuring CO2. I have just been using a pH test to see how its going. I had a pH of 7.6+ without co2, now I am getting 6.6 while the co2 and lights are on and around 7.0 in the morning before the lights come on.

I am still surprised. Even just increasing the lights by 1 hour, I would expect that the pressurized co2 would even further reduce my algae, not the other way around.


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## Shad0w (Nov 13, 2006)

excel do have side effect of killing algae


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## WhiteDevil (May 7, 2009)

my diy and pressurized have some algae in them, but I did notice the pressurized co2 grew it alot faster and more of it then my diy ones does.
however since ive changed to dry ferts its all gone completely, it's ticked my SAE's off pretty bad.


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## bosmahe1 (May 14, 2005)

I noticed you're not adding Nitrogen or Phosphates. Higher CO2 concentration and light will cause the plants to use nutrients more quickly. I would reduce lighting period back to 8 hours and start dosing NPK. The alqae you have in there currently should be removed manually and watch any re occurrence of algae growth. I would also recommend 50 % water changes weekly.


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## joshd (Oct 16, 2009)

shadow and whitedevil - thanks for the input



bosmahe1 said:


> I noticed you're not adding Nitrogen or Phosphates. Higher CO2 concentration and light will cause the plants to use nutrients more quickly. I would reduce lighting period back to 8 hours and start dosing NPK.


Bosmahe1 - I think you are probably spot on and I agree that I likely need to be fertilizing. I do have a question though. If my plants are using up the nitrogen and phosphates what is the algae utilizing to grow?


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## bosmahe1 (May 14, 2005)

joshd said:


> shadow and whitedevil - thanks for the input
> 
> Bosmahe1 - I think you are probably spot on and I agree that I likely need to be fertilizing. I do have a question though. If my plants are using up the nitrogen and phosphates what is the algae utilizing to grow?


Unfortunately, algae can get by on a lot less nutrients than plants. That's why people with non planted tanks and do not dose nutrients and use phosphate and nitrate pads might still have algae if there lights are to bright and their photo period too long.


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## Newt (Apr 1, 2004)

My guess is that your NO3 levels dropped due to more nutrients being assimilated from the CO2. BBA usually needs 2 things to be out of whack. Is your CO2 level approx 30ppm and pretty much steady?
Check out the Method of Controlled Imbalance sticky in the Algae forum.


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