SL Water Dark extract and Sl Soil

[PeidPei]

Hi on a shrimp face book page a person whom i purchased about 25 red wine x white bee mischlings from recommended me to buy SL Soil as I got some bad RO water and now my Ph sits at 7.1. I like that idea but I'm having a hard time with seeing how to approach this. I DON'T want any of my shrimps to die in the process as I've invested a little over 400$ just for stocking it. The tank has a very dense carpet of S.Repens in it. The old substrate is a shrimp soil that only buffers to 6.8 along with some amazonia. Do ya'll think I could just remove all plants from the back of the tank and just pour the new substrate in and replant?? I also want to buy the Water Extract as I like tannins in my water. 

 

I also have some peat moss coming in with a mesh bag. Im not sure why my PH is so high as I removed all rocks and such in my tanks. Should I try the peat first and then consider using the SL aqua soil?