The information I could find online and think brulosophy also did this was 0.3g per 5 US Gals. Which I thought was 18.927 litres. The way I worked out the SMB was 0.3/18.927 = 0.01585037248
Per 1 litre so for a 500ml bottle would be 0.00792518624g. My scales only work to the 0.01g after being calibrated to a 200g weight. So that's the reason I chose 0.01g SMB for the lowest dry amount. With the solution I was able achieve the 0.0079g amount by pipetting 1ml of the solution I made into the each of the bottles.
For the higher quantities the 0.03g dry SMB and the 3ml solution which worked out as 0.024g my rationale was based of another brulosophy experiment in which they used a higher dosage (much higher they used 0.3g SMB Vs 3.0g SMB per 5 us gallon batch
Impact Higher Dosage Rates Of Sodium Metabisulfite (SMB) Have On Beer Character | exBEERiment Results! ) I however didn't want to put that much in so I went down the route of tripling dosage rather than X10. Hopefully this explains my rationale a bit better.
However I do think there was a subtle difference in flavour of the no SMB bottles to all the SMB bottles and I didn't perceive any difference in the SMB bottles taste although this I very anecdotal.
I'm sorry you didn't enjoy my posts however thank you very much for taking the time to read through the thread and commenting. Your points have been taken on board and hopefully as I go and can improve as you and any experienced home brewer have along the way