# Light / Co2 / Fert Balance?



## MrsH (Feb 22, 2009)

150 gallon - have been running 160W, 8hrs per day; recently upped it to 240W. The tank has been up for about 4 months. The plants (heavily planted) are all doing very well. The readings are all good. Daily ferts (Pfertz) w/ a little extra Iron to help green up the plants. Also have a few root tabs scattered about. The Co2 reads 20ppm w/ the chart and the drop-checker says "okay." Would still like to get it up to around 30 - tinkering slightly w/ the Ph controller to make it happen.

*Question: *The "only" (knock on wood) algae that I have ever had is the light green film on the glass. It's very easy to remove, etc. However, it would be much easier to remove if it wasn't there to begin with (lol). *Do you think the daily ferts are contributing to the green algae on the glass? Should I experiment w/ cutting down on the dosage, frequency?* BTW - the amount of algae is exactly the same w/ 240W as it was w/ 160. Thank you!


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## Seattle_Aquarist (Mar 7, 2008)

Hi MrsH,

With the extra lighting, and extra CO2 my guess is you will need more fertilzer, not less. The plants will be growing faster and require more nutrients. Cutting back on your fertilzer may actually cause more algae problems, not less.


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## abcemorse (May 28, 2008)

Personally I like to get the CO2 as high as the fish can handle, regardless of ppm readings which are estimations at best with any measurement technique other than the expensive systems. Just enough not to gas out the fish and good circulation should do the trick! High levels of nutrients do not in and of themselves cause algae if CO2 is good.


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## MrsH (Feb 22, 2009)

/\ /\ - Thank you for the feedbacks. That getting the Co2 as high as possible without gassing out the fish can be a bit scary - especially when some (tetras, for example) can likely stand up to 80 - 90ppm and others can't go nearly that strong. If a range of fish are already in the tank it would seem the balance at the low end of the ppm scale is the "only" way to be safe for the guests!


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## MrsH (Feb 22, 2009)

Seattle_Aquarist said:


> Hi MrsH,
> 
> Cutting back on your fertilzer may actually cause more algae problems, not less.


So ferts won't help grow algae? Or, with higher light and more ferts the plants are growing faster and the algae doesn't have as much of a chance - correct?


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## Seattle_Aquarist (Mar 7, 2008)

Hi MrsH,

I believe that algae is "opportunistic" in that it thrives in situations when normal plants cannot. Different algae types seem to like different enviornments like low nitrogen, low phosphate, low CO2, and poor circulation. 

Since your have increased your light by 50% from 160 to 240 watts, the plants will need more CO2. CO2 provides the carbon molecules which are the basic building blocks of plant cells. It also means the plants will use up more nutrients, if you don't increase your nutrients the nutrient levels in your water column will decrease. The plants may start showing signs deficiencies and the lower nutrient levels may provide the "opportunity" necessary for an algae outbreak. Dosing with fertilizer every day is probably the best, the plants use nutrients every day, the nutrients are replaced when you dose.


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## abcemorse (May 28, 2008)

MrsH said:


> /\ /\ - Thank you for the feedbacks. That getting the Co2 as high as possible without gassing out the fish can be a bit scary - especially when some (tetras, for example) can likely stand up to 80 - 90ppm and others can't go nearly that strong. If a range of fish are already in the tank it would seem the balance at the low end of the ppm scale is the "only" way to be safe for the guests!


Yup, can be a bit scary, just increase slowly and at the first sign of any of the fish gasping at the surface back it off. Biggest thing there is to be sure you can be around for 3-4 hrs after any increase. I run alot of CO2, really (solid stream of bubbles in a 92G), with angels, rummies, cards, plecos, bolivians, rosy barbs, platys, swords, and otos, none seem to have issues, but I don't really know their relative tolerances, may be that they happen to be quite tolerant of it. Nice thing is once you get that dialed in you can relax and enjoy a healthy algae free tank!!


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## MrsH (Feb 22, 2009)

/\ /\ Thank you!


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