Lucas Formula PPM question

Hey guys, I have a question about the target ppm when using the Lucas Formula with GH flora series. Im using a power grower eco and the res is 2.6 gallons. Im currently almost 4 weeks into veg so I added 13ml of micro and 25ml of bloom according to the "0-5-10 - For Vegetative cycle (18/6)" After I add this, I check my PPM and its usually between 480-550. Is this too low? WHats the target PPM for veg and flower using this formula?

This is taken from http://www.drugs-forum.com/growfaq/1654.htm

TDS @ 0.5 conversion:
0-4-8 = 473 ppm
0-5-10 = 592 ppm
0-8-16 = 947 ppm

TDS @ 0.7 conversion:
0-4-8 = 663 ppm
0-5-10 = 829 ppm
0-8-16 = 1326 ppm

I'm a little confused as to what these mean. Whats 0.5 and 0.7 conversion mean? If my PPM is in the 480 range after adding, should I add more to make it closer to the 592ppm(0.5 conversion) or even more to bring it up to 829ppm(0.7 conversion)

Also, Im using RO water, should I be adding cal-mag? If so, how much?

Thanks

Parts per million is measured by something called EC or the electrical conductivity of the solution. The more fertilizer salts in the solution, the more it conducts electricity. PPM pens measure this conductivity.

The .7 conversion is used in the US and the .5 measure is used in Europe. A .7 conversion multiplies the EC by 7 and the .5 pen multiplies the EC by 5. If the EC of the solution is 1 then it is 700 ppm by .7 conversion and 500 ppm by .5 conversion.

Most reference on this and other sites goes by US conversion. You can easily convert between .7 and .5. To convert from .5 to .7 just divide out the five then multiply in the seven. If your .5 meter shows 1000 ppm: Divide out the 5, 1000/5 = 200. We then multiply the result by 7, 200 x 7 = 1400. So 1000 on a .5 meter is 1400 on a .7 meter.

Lets do the math:

Divide out the .5
480/5 = 96

Multiply in the .7
96 x 7 - 672

672 is your .7 PPM

Hope that helps

Damn, never knew that. I have this meter http://www.tdsmeter.com/products/tds4.html. The site says its Conversion Factor: NaCl (avg. 0.5) So I'm assuming this is a .5 meter. So since I'm vegging with a .5 meter(at 0-5-10), I should shoot for 592 PPM?

Thanks