Silicon plus, used as alternative to ph up?

So i went to my local hydro store today as i over used my ph down last night when mixing my tub, usually id throw away and start again but my girls are now in the second week of flower and drinking quite alot, its a 40 litre mix with alot of expensive nutes including canna boost.. the grow shop didnt have ph up but gave me silicon plus as an alternative saying it will benefit my plants as well as been used as a ph up and it was cheaper than a bottle of ph up, but the guidelines dont explain how to properly add it or to what dosage i need if its acting as a ph up, and im pretty sure i read somewere that you shouldnt add the solution straight to your tank, that it should be diluted first but doing that means im over filling my tank and making the mix weaker..

Has anyone experienced this and maybe could share some safe methods on how to applie it more as a ph up...???

My grow shop gave me some samples from GH.Ill check it out.