Good thinking, Pharma and PhilGeis. I should give you more information about what I consider natural. I am ok with either natural or naturally derived preservatives. I am not really interested in any natural certifications.
I was originally thinking on 2% plant based pentylene glycol and 1-2% gluconodelta as a chelating agent because they are easily sourcable where I live. However I will have a look at phytic acid that you recommended.
My other idea was Preservative Eco/geodard etc ( Benzyl alcohol, salicylic acid, glycerin, sorbic acid) but wasn’t sure that would do its job properly at ph3. .