learn something new everyday....It could do both depending on whats in your water lime etc.. i have tap waterthat rises and water that lowers just 20 min drives away from eachother all depends on where the water is sourced. To get a good idea see a water analysis and see what most of your ppms are calcium magnesium etc..
actually good info I have seen it happen in aquariums but not heard of it in hydro... not to be confused with it not happening.If you ph to certain ph's you will break the waters buffer because of log. scales. Cal/mag ionization happens 4.2ph.
Pretty useless information i think though
YesOnce water is phed if u leave it in a container for a few days will the phed drop or raise just from time in the container???