Ph and ec fluctuations

Hi all thanks in advance

I'm currently using advanced nutrients (per litre)
Sensi a + b 2ml
B52 1ml
Senzizym 1ml
Rhino skin 1ml
Bud candy 1ml
Big bud 1ml


My ph is 5.8
My ec is 1.2

Then within 24 hours it has changed to

Ph 4.7
Ec 1.4

Using rdwc method

Also buds seem a little on the small side for day 23 compared to some others I have seen.

Any help would be greatly appreciated

I used Advanced Nutrients sensi for coco a + B (Ph Perfect forumla)
I rarely had any issues with Ph change and I loved the nutes.
I switched to the fox farms trio and I notice my Ph will change as well within a day. My hypothesis is that the waters tempature may change a bit which does casue Ph to rise or fall depending if it got warmer or colder.
I just make sure to Ph right before watering (pain in the ass). The change in EC is kind of weird because I never notice any change in mine.
I am not an experienced grower but those are the things I have learned so far.
Might get more help posting in the hydroponic section

What kind of meter are you using