oh and i found this on another site. it might help you advanced hydro growers..
Addback Calculator - (For Advanced Users)
Say you were running the 0-8-16 formula, at 0.7 conversion with a 22 gallon res. When you first fill it up, your ppm will be around 1330.
Now you have been growing for a week, and some of the water has been taken up by the plants, some has evaporated, and now your res is at 947 ppm. You need to get your ppm from 947 to 1330. Here is the equation:
((target - current) / target) * 8 ml per gallon * res gallons = Flora Micro (ml) double this figure to get Flora Bloom (ml)
Example:
((1330 - 947) / 1330) * 8 * 22
(383 / 1330) * 8 * 22
0.3 * 8 * 22 = 53 ml Flora Micro
53 ml Flora Micro, double that and you get 106 ml Flora Bloom. So 53 ml Flora Micro and 106 ml Flora Bloom to add back to your 22 gallon res to get you from 947 to 1330.
Addback Calculator - (For Advanced Users)
Say you were running the 0-8-16 formula, at 0.7 conversion with a 22 gallon res. When you first fill it up, your ppm will be around 1330.
Now you have been growing for a week, and some of the water has been taken up by the plants, some has evaporated, and now your res is at 947 ppm. You need to get your ppm from 947 to 1330. Here is the equation:
((target - current) / target) * 8 ml per gallon * res gallons = Flora Micro (ml) double this figure to get Flora Bloom (ml)
Example:
((1330 - 947) / 1330) * 8 * 22
(383 / 1330) * 8 * 22
0.3 * 8 * 22 = 53 ml Flora Micro
53 ml Flora Micro, double that and you get 106 ml Flora Bloom. So 53 ml Flora Micro and 106 ml Flora Bloom to add back to your 22 gallon res to get you from 947 to 1330.