Vancefish - he's using coco so it's a little different.

Watering coco everyday is recommended, perhaps every two days, but you don't want coco to dry out like soil. Just let it get a little "light" is how it's been described.

Also plants grown in coco like smaller pots vs. soil grows.

johnboy198 - I can only guess at the problem, it looks like a deficiency, maybe N, but I can't really tell what the cause is. It can be under-fertilized or have lock-out, but I can't make a recommendation on how to fix it on a guess.

Your ph is too high for coco, aim for between 5.8-6.1 going in. Also, you may need CalMag+ to go with your tap water. I'm not sure what the "10" stands for that you are saying is the nute strength, but typically you need an EC meter or ppm meter, they measure the amount of salts (nutes) in your water. Without knowing how much you are feeding, measured by ppm or EC, I can't tell if you are giving them the right amount. How many mL per liter are you giving them?

Check with the Canna website for directions... Coco A & B Directions of Use | CANNA UK, and their feeding schedule http://www.growell.co.uk/?f=download.php&binacode=66. Let us know if you are doing anything other than what they say.

If your tap water has a high ppm/EC then it likely hard enough and has your other nutrients. If it's soft, you'll need the CalMag supplement.

If you can get a better picture it might help, maybe without the hps on?

Sorry I can't be of much more help, hopefully some of the coco growers will catch this, but not too many of them around here I'm afraid.