PH in my DWC dropping too low during late flowering.

[Foxtrot1970]

Distilled water ,AN PH Perfect trio, b-52,bud candy, nirvana,sensi cal/mag extra, overdrive, Purpinator , hydroguard. This ph out to 5.7. 1000ppm water temp 72f.
1st time in dwc. I have noticed through out the grow the ph would rise to 6.2 . I change my water out every 7 days.
right now she is drinking about a gallon a day so I check it every 24 and fill it back up and check ph. It was 5.3 so I ph up to 5.8 the next day back down to 5.3. My ph usually goes up . I refill with distiiled water only when my ppms are still with in good range example ,start with 1000ppm ,check ppms when needing to add water(add water back to level and check ppm)if the ppm is around 900 I just add water if it drops below 800 I will add nutes till she goes back up to 1000.
So why is the ph dropping instead of raising? I posted a picture of her. Thanks for letting me post here fine people.

 

[Wheeler]

When I ran DWC and RDWC in flower the plants would start eating and drinking so much my ph and ppms would jump all over the place. I would have some big ph swings especially I think because of too much air. I just topped off daily and balanced my ph. As long as they were drinking and eating and looked okay I quit worrying. Your pic the plant is a little droopy but buds look to be frosting up nicely with lots of time to grow. I was never able to keep my reservoir too stable but did end up with some nice grows

 

[American Hillbilly]

Take my advice with a grain of salt. As long as your system is healthy (roots look good)....

If your plant is drinking that much, and your res is small, maybe your just building up Carbonic(?) acid in the small amount of water that is left until you top it off. In essence, over aerating the water, forcing the Co2 out, and a buildup of Acid. If I understand that process correctly.

 

[Foxtrot1970]

When I ran DWC and RDWC in flower the plants would start eating and drinking so much my ph and ppms would jump all over the place. I would have some big ph swings especially I think because of too much air. I just topped off daily and balanced my ph. As long as they were drinking and eating and looked okay I quit worrying. Your pic the plant is a little droopy but buds look to be frosting up nicely with lots of time to grow. I was never able to keep my reservoir too stable but did end up with some nice grows

Thanks, I cut down the air at the manifold, will see if that helps. I have a 5 gallon bucket and it holds 3.25 gal with net pot. I noticed that this just started happening with her consuming a lot in one day

 

[Foxtrot1970]

Take my advice with a grain of salt. As long as your system is healthy (roots look good)....

If your plant is drinking that much, and your res is small, maybe your just building up Carbonic(?) acid in the small amount of water that is left until you top it off. In essence, over aerating the water, forcing the Co2 out, and a buildup of Acid. If I understand that process correctly.

I have reduced the air a little we will see what happens,thanks