Why has my pH changed?

[Aquanate]

Hello. I've just setup my first aquariums. They've been running in for four days. The driftwood is cedar. I used Sakrete play sand as well as their all purpose gravel, with lava rock and an unidentified rock my mother had to help hold the wood down until it sinks. I decided to use undergravel filtration. From the tap my water pH is 6. Today I tested it and it read 7.4(to me). T.D.S. went from 20ppm and has risen each day. Now it's at 79ppm. My guess is about a 20ppm increase each day. My pH will determine my choice in what species I need to keep. I haven't changed my water yet. Please help me understand what's happening.

[Fish Folk]

You’ll want to test something.

Test your water straight from the tap again. 

Then, draw a clean glass measuring pitcher of water from your tap, and let it stand for 48 hrs. If you have a way to add an air stone, that’s even better — but not essential. Test after it “rests.”

Also, if possible, test your KH and GH. You want to know how much buffer you have in your water.

You want to learn parameters for your water aside from the tank. If nothing changes from tap to rested water, then you’re looking at something going on in your aquarium itself.

I’m curious about what the unidentified rock is...

 

[Aquanate]

Early on I tested my water tap water fresh and aged. It read 6.0 both times. Tds was 20ppm. When I soaked my driftwood tds dropped a little over a week period to about 18ppm. I assumed it wasn't leeching anything into the water at that point. If anything, I've heard of driftwood bringing pH down. Here's the rock holding down the wood. I have set aside water to test again and will try to have info on kh and gh in a couple of days. Thank you.

Edited March 10, 2022 by Aquanate

[Torrey]

Is the rock changing at all?

That can elevate pH, generally until everything stabilizes not too much above 7.0 (I've tanks that generally stabilize between 7.4 and 7.8 due to rocks). I wonder what your GH and kH are, as that will determine overall stability of parameters.

[Aquanate]

I added lava rock to my scapes. My mother had some rocks I'm using to hold the driftwood down. I'll see about testing for kh and gh soon. Here are the rocks.

[Aquanate]

Kh and gh readings as if today, and I'm sure the rock is river jack stone my mother bought from a local landscaping supply.

Edited March 17, 2022 by Aquanate