Yea, you need to use the phosphoric. And pH needs to be 5.2-5.8 depending on stage of growth. 6.1 is just too high for hydro, possible reason for burning. pH is prob. the biggest cause of nute lockout. I've read water softeners are no good for plants. RO's the way to go if you're serious about growing hydro. Better to know what all is in the water you're feeding your babies.And Cal-Mag+ is a must with RO.
I have learned from experience that if you are gonna invest time and money into growing hydro, you need to do it right and don't cut corners.Otherwise you're just wasting your time and money.If you just want to play around and grow cheap, stick to soil.
It does sound like you are at least a little serious about it, as you did spend the money for the meters.:thumbsup:
If an RO filter is too much $ for you and you have a small set up you can get RO water from those machines in stores and parking lots for $0.25 a gallon.Or at Wal Mart for $0.62 a gallon. Thats what we did at first.
And if you need a very good formula for the GH 3 part, here's what we use:
http://boards.cannabis.com/hydroponi...rt-calmag.html