First loosen the DI while the system is 'open'(water flowing) and let the canister fill to very top with water before sealing/closing.
Ask me how I know?
6 stage DUAL DI with 1 extra canister in front of it all.
I always have to bleed off air when I change the di resin(love the color changing resin even with tds meters built in to my system).
Even with that you will see 'air' possibly while the system is open,but the canister will be full of water under closed pressure....
I tee off before my di so I don't burn it up for my rams water(way over 50% of my RO!).
The meter helps when color is changing.
The upgrade interest me soooo much but.....
would need booster pump(no big deal) and then electric float shutoffs for storage vessel...I have 2 containers now(1 di 1 not)that are ALL GOOD with standard BRS float valves.
I will admit I am not really that comfortable with all it would take to get what I want with the upgrade?.
I schedule and store water like a hoarder!(44/32/5@5 for ro , ro/di)and I prep my tap in 32s also....
I will say 1 canister in front of your system with a 5 micron filter($2.99) will make the whole rest of your system run better/last longer.
I use old school label maker and date each can.
That and the flush valve will make buying the expensive parts way farther apart.
I try to change my 5 micron every 30 days,even thoughthe built in pressure gauge hasn't risen much.
All in all I am happy with my BRS.
Don't close the canisters too tight!They are a SOB to open sometimes(for real!).....