I am going to start injecting CO2 and wanted to make sure that I don't mess
anything up too bad. I plan on doing this with a 1 gallon DIY CO2 reactor.

I have a 50 gal (48x15x16) tank with the following parameters
120w of NO fluorescent
PH 7.5
KH 2
I think this gives me a CO2 level of about 2.5-3 ppm.

My question is should I raise the KH before injecting CO2. I plan on raising
the KH with baking soda. I think I understand the relationship between these
properties but would like to make sure. From my understanding if I raise the
KH to 4 it will bring the PH up to around ~8. And then injecting CO2 will
bring it back down.

Not sure if it is important but tank inhabitants are

4 neon tetras
3 glolite tetras
6 black mollies
6 white cloud danios
2 bronze cories
2 candy tetras
1 male betta
1 common pleco

7 apongeton plants growing from bulbs, not very big yet
dwarf grass
1 red melon sword
5 stem plants

I plan on adding some java fern, java moss and maybe some Amazon swords.

I can post pictures of what I have in the binaries if it will help.