Hi there so i'm going to update this threat,
I brought a electrician guy, to give me powerful output from power meter For HPSs, and i found out that the maximum amount of amp i can use is 25,so i did some research and change the setup to 2*1000w hps and 1*400mh for two last weeks.(30 pot in a 1.2m width , 3.2m length and 3m height in a 3m*4m*3m room)
Soil: i bought 3 bags of premixed soil from a store and bring it home. unfortunately after i watered it, i realised that the soil is very heavy due to it's high amount of composed and organic fertilizer, and the soil was very tight after 24 hours from watering, although there was a good amount of perlite in the mix. and the colour of the mix was so dark.
So i read about how good drainage and light, an auto soil mix should be. Went to another store , we bought about 14 bags of pre mixed soil, and i guesse i should let the soil get dry for couple of days and then add some perlite in it
( lots of talking sorry)
I see some tight big rock of river soil (as u may see in pictures) about 2 to 5 centimetres , i bought a sieve to take them out of mix
Im metric dumb, if its around 6 inches but 8 inches around would be better airflow for the lights