Can you add perlite 3 weeks into veg?!? Coco is too moist

Alright so I'm about 2.5 weeks into veg and I'm having over watering problems on some of the plants. I am getting a 10% runoff with every water/feed and plants begin to droop for a day or two before picking back up. I'm in 100% coco coir and it holds moisture for a long while and really does not dry up very fast. I'm using 3gal fabric pots and giving about 1/2-1 gal to each plant every 2 days or so (for 10-20% runoff) fan leaves seem a darker shade of green and very heavy. So I am wanting to know if I can still add perlite to the pots to allow better water/air flow. If so how would I go about doing it? Grab the plant and pull it out? Maybe rinse off roots? The coco seems to compact a bit when I water and takes multiple days to dry up. Everyone says to keep it wet and water daily. But mine seems to stay wet and makes plants droopy after feeding for couple days. Advice?

alright mate.i had a little problem with amnesia (clone) using coco not so long ago, i didnt read up on coco at first so thought it was nutrient rich its not. as soon as i started nutrients (every feed) and much longer flowering (15 weeks) she perked right up and had really good buds at the end

perlite holds moisture too.