method for what i think you are wanting.

1. use timer 1 set on from 8am to 8pm
2. use timer 2 set on from 8pm to 8am
3. program logic
G1 = level 1 and Timer 1
G2 = level 1 and Timer 2


4. Then assign program logic G1 to socket for pump 1 and program logic G2 to pump for socket 2 if you don't need Ph control if you do ignore this step

5. Now if you want to pump use pump3 for ph<8 then program logic
G5 = Level 1 and Ph Increase
6 assign ph to two position control for ph 8.0 with 0.1 hysteresis and then assign socket for pump 3 to program logic G5

7. Now to stop pump 1 and pump 2 running with ph control them you need another program logic
G3 = program logic G1 NAND PH increase
G4 = program logic G2 NAND PH increase

8. Then assign socket program logic G3 to pump 1 and program logic G4 to pump 2

hope this helps.