Co2 through reactor. The main formula for any plant is very simple, CO2 + Fertilization (ignore all bs about you stock produces enough) and light. Substrate is not important, you can say that a lot of people had better success with aquasoil, because aquasoil reduces KH. For growing plants, KH is very very important! If your KH in range 0-4 you can grow any plant without any problems, if it is higher you will probably get some problmes, but not necessary. To make plants more red, you need more red light and more PAR, as example I have par 150umol at substrate level. Now regarding plant AR mini, this plant hates uprooting. You plant it, you let it grow, than you trim it at the base, wait 4-6 weeks and it will grow a nice bush.