If you follow that mix I gave you, you will not have any problems at all. It is a tried and true recipe that works. Ihave set many people up with it and they still use it after years of growing.
Do not use sand from the Ocean, Too much stuff in it.
With this method you take a WELL rooted clone and put it in the #10 pot and water a little, then add more, you want to water it well the first time. You might not need any water for a little bit.
You do know how to tell if a plant needs water when using soil right? If not follow this, Weigh your pot without any plants in it before watering. That is the weight it should weigh before you water again. You need to let soil dry out a little before you water. In a #10 I only water about once a week with lil clones and later on about twice a week. Do not over water. The more love you show it by watering without need you are doing more harm.
Never water a wet pot. Do not leave water sitting at the bottom of a pot and let the plant drink it back up. Would you want to be drinking your toilet water every day? I sure would not. And neither do the plants.
The HP mix you are using does not have nutes in it. The mix you made sounds like it is missing plenty of stuff.
The recipe I gave you has enough in it to last thru your harvest. Try it out on a few to see if works compared to something else you want to try.
I have found some really good recipes by playing around with Side by Side tests of different soils.
Nowday's I play with Coco. Still using
Smart Pots, but much smaller SP's and harvesting much more with less effort.
Another thing you asked about how much to water. It really depends on your enviroment. If the humidity is too high it will take a while for it to dry out. Just like if it is too dry in your room it will dry out the soil super quick.
Enviroment is pretty much just as or more important than lighting in a grow room.
