Should i switch??

[pat]

Thanks Mike
So now what i need to know is,is this gonna cause havic on my existing water quality?Cause i'm planning on doing this with an established tank and do not wanna kill anything ,not even an amphipode LOL,you know what i mean right.
This tank is slowly being converted to a SPS tank,acropora,montipora few clams and even fewer fish.

Here is a brief discription of what i have going:27g tank,20g sump,needle wheel skimmer rated at450gph,30lbs live rock,30lbs live sand(not for long).
LIVESTOCK
maxima clam,crocea clam,blasstomusa merili,bluetip staghorn,orange montipora,green montipora,montipora confusa,green turbinaria,acropora loripe,bubblegum chalice,bubble coral,hammer head coral,alveopora,purple frily gorgonia,yellow gorgonia,blueberry gorgonia,zoo's,mushrooms,crabs,snails,2 firefish,2 percula clowns,1 cleaner shrimp and peperminth shrimp.