Chaeto Dropped My pH(?)

[Sig32]

Below is my tank info. On Saturday, I placed some chaeto in my tank (about a soft ball size) and my pH dropped immediately (see 2nd pic below). I had previously had pH highs of 8.36-8.4 and lows of 8.04-8.11 rather consistently (see pic).

Since introducing the chaeto, I get pH highs 7.97-8.01 with lows of 7.77-7.82. I am not trying to get caught up in chasing numbers, but I am concerned with the change as I know stability is key in this hobby. Everything I have read about adding chaeto is that it raises pH and helps to lessen its swings, thus my confusion.

Does anyone have any idea what is happening and if I should be concerned? I haven't seen any ill affects from the drop, but I would like to address the issue, if there is one, prior to seeing any.

RSM 250 65 gallons
Alk: 9.1 dKH
Cal: 495 ppm
Mag: 1480 ppm
Nitrate: ~4 ppm
Phos: 0.17 ppm (hanna low phospate)
Dosing BRS 2 part

 

[BlueCoast]

Although a little doubtful, where any other changes made around this time (more closed windows, etc.) Typically you are right about raising PH. That quick drop is odd. Even if some rogue bacteria entered the system it would take longer to drop the PH while they multiplied.

An old trick is to take a cup of water outside and run a bubbler in it for a while then measure ph(preferably with the apex) to see if the co2 in the house is lowering the ph.

 

[Sig32]

Thanks for the reply. There weren't any changes other than adding the chaeto. I was surprised and puzzled with what transpired.