Temporary high phosphates for SPS?

[FishyFishy!]

Reallistically, to do this properly, you would want to run both products on both tanks, so that they are fairly in sync as far as perameters are concerned when you combine the systems. I think that from 0 to around 1.0 is a pretty large difference when phosphates are concerned. I would try to get the parameters more on the same level.

Are you able to put GFO and BioPellets on both tanks to start before you combine them?

Salinity is huge too. I combined two tanks once, not knowing that my salinity was waaaay off in one of the tanks (thanks to a plastic hydrometer) and the tank with the lower salinity's inhabitants all died. (mind you, this was just combining inhabitants into one tank, not sharing system water like you are, but still the same idea).