PH Drops with no CO2

[speedy51]

Hey I need some help with my PH. I just want to say that I am not chasing a perfect PH but just want to understand why this is happening.

Sunday 1/7 I did a 100 gallon water change. The PH from my tap is pretty high around 8.9.

So after the water change the PH jumped to 8.54 then dropped the next morning to 8.03 at 7:30am. By noon it was 8.12 noon, by 7:15am on 1/9 it dropped to 7.57 it has fluctuated a big up and done but has remained around 7.6 or 7.57

I am using a Neptune Apex system and the Probe is brand new. What would cause this?

I am planning on have a tank full of Peacock Cichlids so this PH is low for them.

Any and all ideas are welcome.

thanks
Ed

 

[TMaier]

I had a similar problem and added aragonite to my system. I don’t know the details but it keeps the PH from dropping. I played around with the amount because too much would cause it to increase.

 

[speedy51]

I had a similar problem and added aragonite to my system. I don’t know the details but it keeps the PH from dropping. I played around with the amount because too much would cause it to increase.

Thanks TMaier. My sand bed has a mixture of some aragonite but I guess it's not enough and will require more.

 

[coralbandit]

Have you tested the source water pH after 24 hours in a bucket ?
Your running a sump for gas exchange so no worries on a lid ?
Do you know your KH?

 

[speedy51]

Have you tested the source water pH after 24 hours in a bucket ?
Your running a sump for gas exchange so no worries on a lid ?
Do you know your KH?

Bandit I must admit I've never tested sitting water in a bucket.

I am running a sump which I have partially covered. I have the display with lids which covers 90% of the open area.

I've had this like this for a while since I started up the tank. The only change was the weather.

Since it was cold down here, the a/c was off and all the windows were open. No more cooler days and nights so the windows were closed and the a/c is on.