Importance of keeping PH stable

[CoralMonkey]

How important is it to keep the PH stable all day and night? Does this make a significant difference in sps growth, color, etc??? I know that keeping Alk stable is huge in a sps tank, but what about having daily PH swings from the lights etc?

[klepto]

I'm no chemistry expert here.. but I believe that keeping alkalinity stable will in turn help keep the PH stable.
Here is a good article.
http://reefkeeping.com/issues/2007-05/rhf/index.php

[serpentman]

Nightly pH swings are very difficult to avoid unless you have an equal amount of photosynthesizing animals/plants you can light on a reverse light cycle. Although you can tweak the alk here and there, dosing a ton at night to keep levels raised will only result in higher levels during the day. IMO, worry more about keeping alk constant and let the pH do its thing.

I have not found nightly drops to cause any issues in my system. In the summer and winter my tank varies by 8.1 during the day and 7.8 at night, spring and fall when the house is open that jumps to 8.3 during the day and 8.1 at night.

[Flanders]

a refugium on a reverse-light cycle is the way to go.

[Orr2003]

nightly ph swings are very difficult to avoid unless you have an equal amount of photosynthesizing animals/plants you can light on a reverse light cycle. Although you can tweak the alk here and there, dosing a ton at night to keep levels raised will only result in higher levels during the day. imo, worry more about keeping alk constant and let the ph do its thing.
i have not found nightly drops to cause any issues in my system. In the summer and winter my tank varies by 8.1 during the day and 7.8 at night, spring and fall when the house is open that jumps to 8.3 during the day and 8.1 at night.

+1

[CoralMonkey]

Nightly pH swings are very difficult to avoid unless you have an equal amount of photosynthesizing animals/plants you can light on a reverse light cycle. Although you can tweak the alk here and there, dosing a ton at night to keep levels raised will only result in higher levels during the day. IMO, worry more about keeping alk constant and let the pH do its thing.

I have not found nightly drops to cause any issues in my system. In the summer and winter my tank varies by 8.1 during the day and 7.8 at night, spring and fall when the house is open that jumps to 8.3 during the day and 8.1 at night.

I am picking my new APEX unit up tomorrow and I will finally be able to see how stable or unstable my PH is. I was thinking I would use the APEX to dose 2-part at night when the PH is low.... however now that you mention it, I guess I can see how that may actually make the PH at day higher too. I'm going to do what you said and basically what I am doing already, which is keep the ALK constant as possible and let PH do its thing. Ive seen the pictures of your tank, so if the nightly ph drops are ok with you they are ok with me.

[CoralMonkey]

I'm no chemistry expert here.. but I believe that keeping alkalinity stable will in turn help keep the PH stable.
Here is a good article.
http://reefkeeping.com/issues/2007-05/rhf/index.php

Good article, but I was more questioning if keeping ALK constant there will still be small PH changes, and if minimizing these changes promotes better success with sps.

[harper]

Good article, but I was more questioning if keeping ALK constant there will still be small PH changes, and if minimizing these changes promotes better success with sps.

No pH will still swing with alk constant. People want to treat pH like ALK, CA, NO3, PO4, ect...but simply it is not the same kind of thing. With ALK/calcium/MG you add an amount of them, it is used up and you add more. With nitrates/phosphates most try to remove them (water changes, carbon dosing, gfo, etc). But pH is not that kind of thing. It will move up durring the day with light. Or down at night. Some like to do the reverse light thing with a refuge to keep it more stable. You need to decide if you are interested in keeping a seperate piece of your system filled with algae/or other things. But to the question, a swing of pH for say 7.8-8.4 through the day/night seems to be good and many have tanks loaded with SPS' in such systems. I don't find it of any use to test pH unless you plan on running a calcium reactor.