Hey Harry,
BIG+ for the EC meter, it's a must for hydro. Some can keep their salts down/diluted enough to grow without a meter, but to actually know the salt levels, you need a meter. To get the most out of my grows I run mine at 1/2 the manufacturers recommended EC, for my setup the 'recommended' is way too strong.
That plant is looking pretty good IMHO, yea, burnt tips but without a meter, they could be worse. I also grow SCROG (SCReen Of Green), using nets to spread the growth out. Personally I use 3 layers of nets. The first is a heavy steel net to train the growth out to fill the space, then 2 trailer nets above to support the heavy, weighty buds. One of the big issues when growing scrog is growth management. You want to nurture the growth that's getting direct light and remove the growth that isn't. You want all of the goodness pushed up into the crowns, to this end I strip all of the undergrowth, underneath the canopy. The buds that don't get the full light become light and fluffy rather than nice and dense, the lower darker regions are perfect for moulds to grow and flourish, so I strip it all out to the bare stem.
Another BIG issue growing in a confined space is airflow, you NEED fresh air in and stale used air out, and that air needs to be circulated around the entire space. Pockets of air that doesn't get moved around will build with moisture and moulds love moisture.