Ph Problem - Need Help!

[svirid]

Good day guys,

I have recently tested my pH with the test kit and it showed me about 7.8, right after that I have bought American Pinpoint digital pH meter, to keep an eye on water condition. I read that they are pretty good. After I set it up I have seeing huge jumps in pH of my water. When the light is on it goes up to 8.12. When light is off after an hour it drops to 8, and in the morning I see about 7.8.

Can anybody explain to me what is happening, I thought it should be stable number, low but stable. I wanted to dose some reef buffer to increase pH but It looks like if I dose it calculating form 7.8 it might go to 8.6 when the light is on.

About my tank:

its 28gal reef tank, 150w MH, skimmer, external filter (only holds Rowa and Purigen).

Also the light is on at 14:00 and of at 21:00, can it be the problem?

Thank you very much for your help.

 

[Morri]

Does your temp fluctuant as well as your ph ?

I will hazard a guess that it does if you have a MH light it might be worth looking at this first before buffering.

 

[svirid]

Does your temp fluctuant as well as your ph ?

I will hazard a guess that it does if you have a MH light it might be worth looking at this first before buffering.

No the temp is stable, about 78F, it might go up to 82 but very rarely when the day is very hot. I have fans that keeps cooling of MH lights and water.

 

[Morri]

Daylight cycle can also effect the ph will pm you an article describing this but i am not sure of home much swing to expect mine varies very little but I have a reverse lit sump.