We are creating a concrete shell spa and want 4 jets with independently controlled air induction - one air induction control knob top-side per each jet. We're planning 1/2" PVC from the control knob/valve down to the jet area.

We see posts about check-valve problems leading to jet body replacements
required sometimes... we don't want to embed any jet body needing maintenance in the 8" thick concrete spa shell, but we do want a check valve to prevent water spurting up through the air induction control. We also want air bubbles in the jet output.

Can you recommend a jet and jet body and check-valve we might use? The
idea of a simple directional eyeball type jet would be fine, but I wonder if we need a jet which specifically mixes the air & water, or does suction past the air input pipe draw air in bubble form through and out the jet?

Of course willing to purchase all parts at SpaPartsNat and give it a try with a few experiments... any advice?

You don't need an air check valve, there's a venturi created inside the jet, so as soon as water passes through it, it creates a vacuum. I wouldn't bother with an air blower plumbed into the afc or h20 plumbing either. The jet you're describing is virtually every spa jet, nothing remarkable about it " title="Very Happy" /> Just keep the air lines separate.

Additionally, your 'air control knob' has a check valve built into it. like this one: http://spapartsnet.com/Air-Knobs-Valves... 7_0_1.html