2 grow questions

2 questions from a fellow grower:

How do you get soil from around the roots to test it?

If you had a choice between running three 200 watt cf or three 175 watt hid or hps what would you choose and why?

I always use HID lamps. T5 for seedlings and clones.

Why do you need to test the soil around your roots?

Would also know how to test soil at roots I think Roberts bible suggest to test periodically with special type of water

You either get a garden soil tester, or read your runoff with a PH pen