I don't have any experience with canna nutrient except for Cannazym, Cannaboost, and Rhisotonic... But it seems low really. Under a lot of HID light, especially using a 1000 watt light at a foot or so- you need to feed them at least 1000 ppm on a .5 meter in every single nutrient formula I've ever used.
At 8 inches, the amount of lumens those plants were getting were actually overboard if you want to maximize yield. A 1000 watt light will lose footprint the closer you hang it and the large footprint at a high hanging point is it's strong point. The leaves will block the light from getting further down the plant and the light is actually wasted that way. By hanging the light higher, at 2 feet, you can get a great 4X4 footprint of light to work with.
You can use a lumen meter to see just how much light you can work with with the light hung higher. Sometimes closer is not better, especially with a 1000 watt light. It's because of the leaves blocking light to the lower parts of the plant.
Also if you are fighting powdery mildew- you should look into spraying them with an organic tea made with compost dominated by beneficial fungus and bacteria. A beneficial fungus type called trichodermia will actually even eat it and then guard it! There are lots of products with it, like Advanced Nutrients Piranha, or that Organism from Roots organics. But with a good organic tea it should dominate the leaves and cause the mildew not not have any room to grow. It's like a parking lot not having any more parking spots.
Plus, the beneficial microbes produce powerful growth and bloom enhancing hormones. So yet another reason to try it. lol
You might want to look into a HEPA filter as well. Make sure you don't see that demon mold again!
Edited by Mr.GoodStuff, 03 July 2009 - 05:05 AM.