dehumidifier capacity ?

hello guys.

i cant decide how big dehumidifier i should buy 20 litre or 10 litre ? the biggest dehumidifier that i can find has 19 litre dehumidification capacity and 200m3 air capacity .

i have a grow tent ( 120 cm X 120cm X 200cm ) with 600W hps, a exhaust fan and an active intake.

RH is bewteen 65 % - 85% outside . RH was over than 90% in last summer .

it is my plan :

i was just thinking the exact same thing! i have a loft tent set up and exhaust intake is getting harder!to be honest i dont think the air has to be that fresh some dehums ( i heard) have air filters on them anyway so maybe , what i was think was to find one that blows the dehumidified air into the tent via ducting??!

and have it sitting just outside the tent in a room!