Why does my pH keep changing in Germany? I set my ...

You may get water from different sources, and they will have different pH. Some fertilizers come ph-balanced and buffered. I don't think it is available in germany, but my jacks hydro nutes don't require and ph-balancing. After i add it to my tap, it's ~6-6.2pH every time (my strips are not precise). It doesn't matter if it comes out of the tap at 8.4 or 7, which is the range of experience the past 6 years. ph drift is more about shitty nutes than anything else, lol. The plant can contribute a bit. A portion of what it takes in is not through diffusion but 'active transport.' So, it can partially deplete P or K without taking in other molecules. This may also cause a shift in pH. The acid used to ph-balance is not the cause of pH drift like many believe. You are fine using a cheap acid like acitic acid (white distilled vinegar). The lack of buffering is what allows for pH drift to occur.. small numbers of H+ / OH- interacting to cause a shifting value on the scale. Soil nutes will be worse offenders of ph drift. Try some soilless/hydro nutes by a reputable brand... not one with catroon graphics on the label, lol.

Sometimes municipalities have heavily buffered water, as others have said your pipes can contribute, and even acid-rain phenomenon can impact your tap. Are you giving proper time for your pH to stabilize after mixing up? I know is I am having tap water issues the waiting an hour or so for the full RDWC system to reach equilibrium can get really monotonous when you have to iterate again and again.

Mal beim Wasserlieferanten bzgl den Stadtwerken nachgefragt ? Evtl bekommst zu Wasser aus verschiedenen Quellen. Oft kannst du bei deinen Stadtwerken nachgucken, wogenau das Wasser in der Gegend her kommt

I think it might have to do with the water sitting in the pipes for different lengths of time. The pipes might release minerals or react with the standing water. You could try to let the water run for a bit until you feel it getting cold insuring that you bled all the standing water in the house piping. Just an idea though.

HI bud. I'm not entirely sure what you mean when you say you "set your water at 5.9". Are we talking about a basin full of water? I don't know about it being the German water specifically, or the water in your house. PH and mineral content can differ from house to house due to water pipes. If yours is fluctuating after being in the basin, is your basin/container sterile and clean? Secondly, you could fill the basin and don't add additives nor ph it for a few hours until the waters original ph has settled. It will require more preparation time, but that my settle your issue. Have you done EC and PPM testings on your water before? I would be interested in knowing if they fluctuate too. If so, which values are fluctuating.