Dissolved oxygen levels and air diffuser rings

hi

I have a RDWC system that has air rings in each pot. I've recently changed air rings as I was changing out the pipes after root issues. I used soaker hose instead for a temp measure, bubbles look a lot bigger so I've managed to source the original hose from ali express (I refuse to spend £10 for each new air ring I know its sounds mean but that adds up with 15 pots)
Would the bigger bubbles REALLY matter?
I've bought some jacuzzi test strips but they reading at around 2ppm, even water straight out the tap is lower, so I'm thinking these are wildly unreliable?
Water temp at 65-67F
I've attached photo

PEACE
IMG_20211028_183007.jpg
 
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