First grow here i was given some 7 gal fabric pots.are these too big or should i go with 3 gal im growing in soil in a 4x6 space.

You growing autos or photo- periods? 7 might be a tad big for an auto, but you could still use it and if your growing photos then you can use as big a pot as you want to grow the plant out to. I believe most people use 5 gal for autos but I have actually thought about using 7 myself just for the extra space to work with top of soil.

How many plants do you plan to grow? 7gal will work fine. Just can be a little more prone to overwatering when you're new and in a large container with a small plant. But learning how to water properly will come with experience.

Ive got 4 photos right now but would like to do 6 in the future. yes watering seems a bit confusing to me. how much run off is ok

Ok, yeah 6 plants in 7gal pots will be fine for that 4'x6' grow space. That would give each plant a 2'x2' space. Just don't veg for too long or else you'll run out of space.

To answer your question about runoff, it seems most growers do at least 10% runoff. Some do 20% or even more. That's when using synthetic nutrients. If you're growing with organic nutrients, many growers don't do any runoff.

Ok thanks i went with 4 plants in7 gal

and it looks like 6 plants would fit .im using ocean forest and will use the trio when needed. getting a ppm tester this