Big PH drop at night

[milkshake]

I am currently using Mrs. Wages for my liquid lime water. I noticed yesterday that the PH was 8.14 on my Aqua Controller JR. before I went to bed. I arrose and noticed that it was 8.00 Is this common or uncommon? I didn't think that it would drop that much at night. I have a 65W PC fixture over my fuge area at night to try and keep the PH up, but does not seem to work.

[john f]

That's a pretty small drop IMO.

Mine goes from 8.4 to 8.2 every day.

I've had tanks in the past go from 8.5 to 8.0 every night with no ill effects, although more stability is always better.

BTW, what is your ALK?? If you keep ALK over 3 meq/l pH will not be an issue IME.

John

[milkshake]

Ok, I just wanted to make sure.

[Randy Holmes-Farley]

It is normal for pH to drop at night as organisms produce CO2, and normal for it to rise during the day as photosynthetic organisms consume CO2.

Perfect aeration with normal air will prevent any ph swing, and adding the limewater mostly at night will also help boost the daily low.

If the daily low is not below 8.0, I probably would not worry about it too much. :)

This article has more:

Low pH: Causes and Cures
http://reefkeeping.com/issues/2004-09/rhf/index.htm

[MJAnderson]

Randy,

I'm cooking up my auto topoff plans and was thinking of running it just at night to level out PH. I'm currently losing about 1.5g per day from evap. My alk is 8 dkh.

What is better to have --- the more stable PH from dosing kalk during the evening only or the more stable SG from toping off all day?

[milkshake]

That's a good question MJ.

[Randy Holmes-Farley]

The sg change is fairly small if 2% evaporates out each day. From 1.025, for example ,to 1.0255.

pH stability, per se, is not a concern, but keeping the pH above 8.0 is, IMO.