low ph

[tanksalot]

Ive spent the past hour looking through past threads but could not find an answer to this question.
My Ph has been low of late 7.7-8.0, Because its been so hot latley my tank temp has been high, around 84-85° during the day. could the higher tank temp cause my ph to be low?
Ive tested the following,
cal-380 to 400
alk- between 7.7 & 8.0 kh
Amonia-0
nitrite-0
nitrate-0
Fish seem fine, some coarls are happy as they have ever been, My hard coarls are a little unhappy.
Thanks in advance

 

[jarvis]

Four things come to mind when a low PH is present. Poor gas exchange, improperly mixed salt, A whole lot of cyno more than you can shake a stick at, or a very hevily imbalanced Ca and Alk levels.

 

[tanksalot]

I do have a lot of cyno. I know my cal is on the low side, is my alk way off or is it ok?

 

[jarvis]

1 look into how much circulation you have in your tank
2 do you have a skimmer?
3 what kind of bioload do you have on the tank?

 

[tanksalot]

its a 90gal. tank with 2 powerheads plus the return from the sump. I only have one coral beauty and one clown fish. 2 shrimp some small snails, 4 or 5 hermits, and some coarls.
No skimmer

 

[broomer5]

The pH can be affected by temperature.
As temperature fluctuates - the hydrogen ion activity may change, but I doubt that the temperature changes we normally experience in our tanks would cause much of a difference.
Near the same "number" of hydrogen ions would be present - even if the temperature moves a few degrees up or down.
If you are using an electronic pH glass probe/readout - this device should be temperature compensated. If it's not - or the temp comp is broken - you could see some error introduced to the reading.
I'm not sure if our test kits are accurate enough to detect pH changes due to temperature changes. I think the change - if any - is very small.
CO2 gas concentrations in solution on the other hand DOES change as the water temperature changes.
More CO2 gas in solution would tend to form more carbonic acid - that may pull the pH down. Less CO2 would tend to shift the reaction and allow the pH to rise back up.
A change in pH from temperature change may be related to this CO2 gas concentration.
Or not ...... I really don't know for sure this case.

 

[lopeyc]

...are you testing at night? pH is much lower then.

 

[tanksalot]

I am testing at night, but is it normal for ph to drop that low?

 

[tanksalot]

i have a refugium lit 24/7 also but i do not drip kalk. When i say i test at night i mean towards the end of the light cycle, not when the lights are off.
Just a side note i thank everyone that responded your help is much appreciated

 

[lopeyc]

In the middle of the night, my pH is 8.0