CO2 system and Ph swing??

[nature]

hey all... have 5 ft planted tank with co2 system on a timer, ph during the day after co2 on is around 7 but also found tht in the mornin ph is around 7.8... has any1 find this is so? if not how can i rectify the ph swing? Planning to keep discus and been readin that best is 6.5 to 7... kh is 5 temp 27.5... no fish present yet except algae eater ones
thx in advance

[goldenpigeon]

do you have any air stones in there? is there much filtration? is there much surface movement?

[duck]

In the morning the PH should be lower as plant's produce CO2 at night.
What rock's do you have if any?
What substrate ?
It's something in your tank raising the PH.

[nature]

i have 1 eheim 2226, with spray bar under the surface abt 5 cm hitting accros... then 2213 with spray bar rippling the surface... 1 filter at each end... just normal gravel mixed with terralite and some dupla k balls... other than tht nothin else... no airstone nor rock.

[chrissyoscar]

How much Co2 are you putting into the tank.
Co2 reduces ph so if your ph is lower during the day then it could be you're got to much Co2 in your tank.
I'm far from an expert but it's just a thought.

Oscar

[goldenpigeon]

ok do you know that surface movement will cause the co2 to escape? try to lower the level of surface filtration and see if that makes a difference

[nature]

ok will aim both spray bar down, ph is 7 at moment just have to see tomorrow morning... will keep posted
thx oscar 4 the thought, co2 output durin daytime is perfect... wht plaque me is durin nite time when i measure the ph again hehehe