Help a brother out with a ph mystery

K so lately I've been trying to really science up my grow skills and I'm running into a ph problem in my res and I'm not even doing true hydro! I've got raised soil beds that I'm hand watering with a pump and wand and I've been noticing something I'll mix my res (proper order to minimize covalant bonding)
Then ph I'll make sure my ph is holding for a few minutes before I start watering. When I'm done watering I'll check my ph in the res again and it's always wayyyy out of whack I phed to 6.5 today's and when I was done it was 7.3!!!
The worst is when i do fulvic, humic, b vitamin and calmag
conditions:
Using tap water ppm around 150 ph close to 7

Res size 1000 litres

Using a bubbler to recirculate and air-rate the water

Any help is appreciated I know I'm probably missing something big here

is the bubbler strong enough to keep the water recirculating in a res that big?

I'm suspecting there is something in your soil medium is making the PH rise. What are you using? Coco has a high PH. I don't have experience growing in straight coco so I might not be the best help but this looks useful. https://www.rollitup.org/t/for-those-thinking-coco.401052/ make sure your nutrients are compatible with coco. i would try phing at 5.8. also cheap meters are usually junk. get a reputable expensive one. the cheap milwaukees are junk but the expensive ones are great. customer service is also awesome.

That's an awful big res.....How long does it last?
How old or how long has this nutrient been mixed?
What do you use for up and down?
I don't really understand pre charging so much unless, (I hate to ask but,) how many plants?

Do you bubble out your water and wait an hour or so before balancing or do you do it immediately after adding chems.
I ask because if you bubble your water for an hour or so it gets rid of the chlorine from the tap and as a result your ph will rise.
If you bubble out your water before hand or just re calibrate after a few hours then the solution should stay rock solid at the ph selected.
This was also a mystery for me and after some searching I found this answer, hope it assists.

Ok I'm just gonna review this I think there's a Miscommunication. Im hand water with no run off yes it's a big res and it only last one water. I'm checking the ph of the extra water that has never seen soil.
My bubbler is plenty big enough 2 stones. And I'm letting my water airate for 24 hours before I mix. I'm using a blue meter so no trouble there

Sounds to me like you need some more time between final set and watering. After you ph balance the rez for a 2nd time and allow to settle does it continue to rize or stay set? 1000L is a large rez and that could be the issue here is that it take s longer to stabilize with the buffers ect an amount of that size say vs 100L

I think letting it sit is the answer I was just trying to avoid bonding so I was trying to get it on the roots asap

Is it an aeration wand?. Spray some into a separate bucket and test the ph again.

don't ph

problem solved

- Jiji

Use AN ph perfect now you take that out of the puzzle