PJ, you got to get one of these...this is an in-expensive one...
http://cgi.ebay.com/NEW-Accurate-DIG...QQcmdZViewItem

as Z stated above, you have to have good ph...you can watch your ppm's by not over doing mixes, but ph can be tricky...shop around, but you won't find a better deal than the one above to get you started...If you miss this one, check sellers other items and he might have a full stock of them. hope this helps. lw
latewood Reviewed by latewood on . nutes and bubblers...? Got a question for you gurus... I am planning to use the bubbler method. MY question is: How do you fertilize the bubblers? Like after you do it the first time, do you just measure the nute levels then add more at some point or is it necessary to drain all the water and add fresh water and more nutes? Can you do this without an expensive digital meter? Usualy how often do you need to add more nutes? Rating: 5