When I run coco I like to keep my pH around 5.7 / 5.8 in a recirculating system.
I'd suggest you pH your nutes to closer to 5.8 then 6
http://www.marijuanapassion.com/forum/showthread.php?t=1908
Hydroponics is growing plants in an inert medium.
Hand watering an inert growth medium is often referred to as "passive hydroponics".
While it is very difficult to overwater coco or coco/perlite mix's I wouldn't recommend trying to.
Are you pH'n your nutrients to between 5.5 / 5.8 pH ?
My choice would be "ebb n flow" table. It's a very flexible option, for different mediums and pots. It is also easily converted to a "drip" system, my preferred growing method.
I'm very sceptical that pollen from a previous grow is the cause of seeds during your current grow.
Some hermaphrodite plants are very good at hiding male flowers.
If you are to continue flowering your current crop, I'd urge you to perform a thorough search of all of your plants to find the...