My brother has a 75g tank set up with 4 red phantoms, 4 black phantoms, 8 ottos, some ghost shrimp, and about 20 white clouds.
His PH will be up around 6.8 or 7.0 when he does a water change but then at the end of the week it will be very low like 6.4 or lower. He decided it was his gravel and we were going to change it last night. When we took the logs out of his tank, it smelled like it was rotting. He called a fish place and asked if that could be the reason and they said yes.
Is this the most likely cause?