You might email Claus and Troels.
They are welcomed to email me about adding more PO4 and it's relationship to GSA.
But Claus said this about dilute formulas: simply add more.
That;s fine if you do not mind more NO3/K+.
But if you want to help increase the PO4, just add a couple of teaspoons of KH2PO4, which cost less, to the Tropica product.

My conversations with Claus some nearly 10 years ago in SF led to those products. Prior they just made the Trace mix. Same with SeaChem and Kent and others.

Sort of turned the entire notion about PO4 back in the mid 1990's on it's end.

Regards,
Tom Barr