day 26 flower

Hi I am on day 26 of flower I run 1xopen 600w hps 3xcool tube 600w hps and 1x 400w led and 1x 600w led . I have a 8000 btu portable ac 2 X oscillating fan's and a 2500 cfm box fan which pulls the air from outside through the cool tubes and dumps it back outside . I am in canna coco hydro 60/40 mix drain to waste water daily @ 6.o ph and have just climbed up to 1.5 ec adding 30 ml of pk to my 50l water tank /feeding bucket . I am also running co2 on a regulator and timer (no monitor)15 mins each hour in my 11ft by 11ft space . I have dinachem ghost train haze. Lsd and white Russian i have a slight problem in my sealed room where my rh has always been 55 but it has jumped to 60 for an unknown reason and even when I turn on heater fan it just rises. Even when I open the door for a while it stays same , could this be more growth of foliage? My ac can only function as an ac or dehumidifier at one time so at night I turn on heater fan and dehumidifier and this has also felt the rise of rh from 55 to 60/62, also one last thing is if I water at 1.5 ph and the runoff is 1.2ph is this good or bad and where is my optimal runoff point so I know if they are eating and how much.

Plants release a lot of excess water into the air through their leaves (transpiration), causing humidity to rise quickly ( especially in a sealed room).
buy a small humidifier that you can run during the day. This should lower humidity quite a bit.

Ec of runoff should be about the same as that of input water or a little bit lower. A higher ec (above 1,5) of runoff means there is a salt buildup in the coco which can burn roots.

An AC should dehumidify as it cools. Shouldn't need to switch back and forth.

If you can stay 60%RH or lower, with good airflow, you should be fine.

Your grow looks great, just chillax.

When lights are off the cold air from the ac makes the rh rise to 70s so I switch to dehumidifier and run the fan heater on the floor also and then it maintains 21 oc and 51rh . I read that a lot of fluctuation in both of these is not good?

Yes indoor plants like a stable climate without a lot of fluctuations in temp and rh but cannabis is a hardy plant and can withstand some stress.