base rock...

[Scorpion]

is it safe to add base rock (reef rock) to a tank that has already been running for about 9 months? will it make my levels (ammonia, nitrate, nitrite, PH) go wack??

i have a 33 gallon tank with about 20 lbs of live rock in the tank. it's not a reef tank yet, but i want to turn it into one. i also have 2 clowns, 1 blue damsel, 1 cleaner shrimp, some hermits, and some snails. i was doing some research and found out that you could use base rock to build the majority of your structures, then add some live rock to seed the base rock. i wish i had known this earlier. i thought that i had to buy tons of live rock which would cost an arm and a leg.

also... if i'm able to add base rock to the tank, about how long does it take for it to become live rock?