# Lighting schedule with Co2



## milesm (Apr 4, 2006)

if you get that second fluval, you should try to achieve a 1 point drop in pH before the lights are at 100%. turn off co2 about an hour before lights start the ramp down. my photoperiod is 7 hours and i run co2 for 10 hours. and you need to dose macro nutrients n, p, and k. flourish supplies micros. can eliminate excel.


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## Trailmixguy (Nov 21, 2018)

1 point seems like a big drop everyday for the fish. How much time do you do it over and what is your ph range during the day?


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## Immortal1 (Feb 18, 2015)

milesm said:


> if you get that second fluval, you should try to achieve a 1 point drop in pH before the lights are at 100%. turn off co2 about an hour before lights start the ramp down. my photoperiod is 7 hours and i run co2 for 10 hours. and you need to dose macro nutrients n, p, and k. flourish supplies micros. can eliminate excel.



Was going to say about the same. I would suggest getting an inexpensive pH probe from fleabay ($15). This will help you figure out how long it takes to lower your tank pH (increase your co2 level). It will also be useful in figuring out better ways (faster ways) to ramp up your co2 levels. Once you have that figured out, then it will be much easier to determine when to turn on the co2 vs when your lights turn on. 



Your lighting schedule does seem a bit long which in the long run may lead to algae issues. A second light would obviously create more PAR (light power) in the tank which should allow you to shorten your ramp times and still achieve the same plant growth.


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## Maryland Guppy (Dec 6, 2014)

Trailmixguy said:


> 1 point seems like a big drop everyday for the fish. How much time do you do it over and what is your ph range during the day?


Why would a 1.0 pH drop seem large for phish? Many run a higher drop.

Typically this drop should be achieved 1.5 hours or less into photo-period.
CO2 just comes on early before lights on.

CO2 promotes carbonic acid which lowers pH.
Carbonic acid is too weak to remove any alkalinity (KH) unlike stronger acids.
Released hydrogen ions lower the pH, the reaction goes in reverse when CO2 is turned off and/or de-gassed by some method.
GH & KH basically remain untouched.

Many would agree that GH and alkalinity are the prime factors regarding phish health.


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## Greggz (May 19, 2008)

Maryland Guppy said:


> Why would a 1.0 pH drop seem large for phish? Many run a higher drop.


Yeah I am at 1.35 drop, no issues with fish.

Like mentioned above, get a pH probe and calibration fluids.

Adjust things slowly, keeping an eye on fish and plants. Takes some time and effort, but in doing so you will find the sweet spot for your tank.


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## milesm (Apr 4, 2006)

Trailmixguy said:


> 1 point seems like a big drop everyday for the fish. How much time do you do it over and what is your ph range during the day?


duration: 2 hours and 45 min. to get 1 pt drop. range: 7.65 (before light) to 6.55 (one hour before lights off). 

heavy pearling after 1 hour. scape dominated by stems.



Maryland Guppy said:


> Why would a 1.0 pH drop seem large for phish? Many run a higher drop.
> 
> Typically this drop should be achieved 1.5 hours or less into photo-period.
> CO2 just comes on early before lights on.


i used to run my co2 to get 1 pt pH drop after 2 hours after lights on. after i achieved the drop at lights on, plant growth exploded. light the same, fertz the same, same co2 injection rate.


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## Trailmixguy (Nov 21, 2018)

Thanks for the suggestions. I see now that pH fluctuation from Co2 is not as much to worry about as opposed to pH fluctuation from Kh shifts. I'm wondering what Kh I should try maintain. My tap water is about 3. I have seen some people recommending 6 on the basis that alkalinity pH more stable at that level.


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## Maryland Guppy (Dec 6, 2014)

Trailmixguy said:


> I'm wondering what Kh I should try maintain. My tap water is about 3.


Nothing wrong with a KH of 3 regarding pH swings as long as it will suit the variety of phish you wish to maintain.



milesm said:


> duration: 2 hours and 45 min. to get 1 pt drop. range: 7.65 (before light) to 6.55 (one hour before lights off).


7.65 before lights to 6.55 lights-1hour does not provide the 30ppm target during the majority of the photo-period.
Or did I read something wrong here?

Better to peak early and maintain than take almost an entire photo-period to get to desired pH levels.


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## milesm (Apr 4, 2006)

Maryland Guppy said:


> Nothing wrong with a KH of 3 regarding pH swings as long as it will suit the variety of phish you wish to maintain.
> 
> 
> 
> ...


baseline (no light) pH is 7.65. run co2 for 3 hours, not only 1. after 3 hours, pH is ~6.65 when lights come on and drifts down to 6.55 at lights out.


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