My Shrimp Home In Making!

i'm trying to set a PRL only tank, to me is a major project and i would like to make it a successful one. sorry for the lousy drawing as shown but i decided to set up my tank like this. divided 9 '' by 9 '' by 9 '' by 9 '' and leave out a 3'' place for K1 media. Is this idea viable? cos due to my stand, the tank must be made in an awkward height.

i'll be using undergravel filter connected to two canister filter, 1200 L/hr to chiller then back to the tank via 3.5 ft rain bar. the divider wont consist of any holes, and i have a black background with T5 lighting.

i have a couple of newbie questions.. and have to seek the shi fus here

firstly... the K1 medias... i have to use an air stone to circulate the K1, will that increase the O2 level by alot? increasing ph as well? i will not be pumping Co2 inside as i'll keep the set up simple and neat, keeping the PH around 5.5-6.5.

secondly .. the divider height.. what will be the recommend height? my soil will be 4 cm high, should the gap be 3 cm? since the ungravel filter will increase the height of the soil. if i silicon the divider first... how do i fit the plates?... or should i place the plates then silicon? please enlighten me..
Any shi fu can recommend me reliable brand of undergravel plates that can connect to canister filters

i will continue to update when i decom my tank. Any recommends and feedback, positive or negative will be accepted thanks in advance!!