Riddle me this PH Question

[Allenpro]

I have been growing in Hydro for about 13 years, DWC, RDWC, Coco Coir & Ebb & Flow. Why does water/feed in motion (RDWC) need PH UP but water that is not constantly moving have a tendency to need PH UP? I ran the RDWC for years and I bought a PH Doser to keep the PH up and it worked great. Now I have switched to Ebb & Flow and and it seems more common for that res to need PH Up. Same well water and same nute mix the only change is the water isnt moving all the time. I wish the blue labs PH doser had 2 lines, one for Up and one For down but it doesnt. Any Ideas?

 

[Wayzee]

I was reading somewhere that it's got to do with as the water circulated and is exposed to the air either via air pump and or water pump for rdwc it depletes something... Could be clutching at straws here but it does ring a bell.
I had the same problem with my rdwc, constantly adding vinegar or citric acid, sometimes 3 times a day, was a pita. Hence why I'm trying soil.

 

[Allenpro]

I do/did have airstones in both the RDWC and the reserivors for DWC, Ebb & Flow and the RDWC but I think you must be right. If you liked the growth in RDWC you will be very disappointed in soil but until you get a plan to raise the brix in a hydro grow the weed will have a better taste in soil.

 

[Wayzee]

I am an impatient bastard, but I do much prefer quality over everything else.

 

[golfnrl]

Interesting question. I run the autopot system using 12gal rez. I used an airstone in the rez but had major PH down fluctuations. This forum suggested an aquarium pump as the o2 from the airstone was the problem. I now have a pump set to circulate the water for 5 mins every three hours. I still have fluctuation down issues just not as severe or as often. Makes me wonder if the city where I live has changed the way they treat the drinking water. IDK. I'm with ya on the Blue Lab controller. Having both PH up and down would make things simpler.

 

[Allenpro]

I think that is the standard if the water is stationary it will need ph down and moving water needs ph up. No idea why, maybe google knows, I would ask but I am already too dependent on Google and Utube. I have used the same well water for both and up here in Maine we have great water quality so I dont think that has much to do with it.