controlling ph swing

[jersey jeff]

I was wondering how to control the swing of ph during night time.I just recently started adding kalkwasser with a five gallon dosing tank.Dkh is a little high about 14 calcium is 410 ph during the day 8.23. I'm afraid if I up the dose of kalk the salinity may drop

[Junkzoo]

If you have a sump/refuge, a lot of people light that up during the nitetime(darkness in the display tank) periods. That will slow the Ph swings a great deal.

Reverse lighting is what is used in this situation .

If this is not a option, i really don't know what to offer .

HTH.

[cerobbins]

First thing that comes to mind is a fuge with a reverse lighting schedule, but I would ask how big of a Ph swing do you experience. Everyone has a swing and if yours is in an acceptable range then I think you are trying to fight a battle you cannot win.

[crvz]

My first question would be, why do you want to control it? In my experience, there is absolutely no need to do so. While a reverse photoperiod will probably impact pH, I don't think there's an adequate way to control it. Like cerobbins says, as long as it's not falling below about 7.8 or climbing above 8.5, I would never do anything to actively alter pH.

[Loverotties]

Swing is normal between the day and night.But if you use reverse lighting it will cut down the swing.

[tdwyatt]

Originally Posted by jersey jeff

...wondering how to control the swing of ph during night time. I just recently started adding kalkwasser with a five gallon dosing tank. Dkh is a little high about 14 calcium is 410 ph during the day 8.23. I'm afraid if I up the dose of kalk the salinity may drop

You do not need more kalk, adding or increaing the alkainity in your tank will not control the swing you are experiencing. The swing in pH is controlled byhow much CO2 is present in the water, and as the pH is almost in constant equilibrium with the atmosphere (and buffer equilibrium is much slower), changes in water column pH are more directly a reflectiion of the pCO2 in the water (its equilibrium rate is much faster than rates of change induced by the bicarbonate/carbonate buffer system).

While the lights are on, photosynthesis rates by photoautotrophs (like coralline algae or Zooanthellae are usually very rapid, and their rate of consumption of CO2 can easily exceed the rate at which CO2 can diffuse back into the tank water, so pH gradually rises up to peak pH levels of 8.3 to 8.5 by the end of the photoperiod. When the lights go out, photosynthesis stops using CO2, and even the photoautotrophs become net producers of CO2 as they turn stored CHO's into CO2 via cellular respiration for the chemical energy during the night. This causes the pH to fall during the night, usually to a nadir of 8.0 to 7.9 depending on several factors.

As already pointed out, there is no issue with the system's diurnal swing in these values, and unless you're introducing a new Ca reactor and the nadirs are below 7.9 at night, then you really do not have any issues in this situation.

Normal tank variation, nothing to worry about.

HTH

[FLjoe]

thanks for this info, it really helped

[tdwyatt]

I didn't remember this at first...


...too much end-of-the-semester and Chrsitmas holiday stuff!