Ports on bottle seal.

I just made my first batch of nutrients today and noticed they all seem to have a little circle looking thing on the safety seals.

It was perfect since I’m using a syringe to suck up and measure them anyway but is that what they’re for??


Also the grow and bloom bottles are super thick like syrup and the safety seals were huge and seem really hard to peel off.

Is that all normal? And what do you guys use to measure the stuff out??

I use a 12ml syringe. I mix a gallon or 2 at a time.
I drilled a 5/32 hole in all my caps that the syringe seals right into. No mess at all You could leave the syringe in the hole to seal it, A golf tee might be perfect.

Anyway,I always thought that little circle was for your straw?