Bretts,
I thought I might get a response from you re the refractometer
First, I use the commercial Seasol and I brew my own seaweed extract from locally collected kelp. I have used my home brew for years on the garden with good results.
Maybe it is an overkill to use them both together? Dunno
My homebrew had a refrac measurment of 4 brix in late July after 3 weeks. It is sitting now at 11 brix and is nearly all disolved.
According to Arden Andersen anything above 12 brix is good. He quotes 14 as being "the number"
I don't use the readings as a science, more as a guideline. It is important to ensure that the measurements are made under similar circumstances every time. This will give you consistancy. Don't take a measurment one day prior to watering and the following measurement is made a day after watering and fertilising!
By doing this you get a good picture.
I have never been able to get any measurments above 12 brix. Maybe 12 is "my perfect number". I'm happy between 10 and 12. If one day I get a measurement that is a lot lower I have to figure out why and there could be a number of reasons; water stress, forgot to fertilise etc
I keep also a "test plot" of lawn that I test frequently and that scores consistently at 12 brix. It is nice green and lucious.I suppose you can call this my measuring stick
I'm not bothered that I haven't got to 14 brix. It's only a number and by looking at the trees I think I'm on the right track.
Just a note out of the blue now I think about it: An aphid infestation is a sure sign of too much N in your plant!
Yes, I have aphids periodically
BoNZai