Quote Originally Posted by bronc76
What is a good rule of thumb to start at with the ppm's?

I have no idea what the ppms would be with my current recipe will be nice to know.

The tds meter is $129.00 at the hydro store will take me a week or so to get the cash.
Rule of thumb, start off light.

When you take cuttings for cloning, you want your ppm to be at 250 with a good light starter mix. After they root and you place them into a medium to veg, you can up the ppm's to 3-400. These ppm's need to be made up of N-P-K, micro nutes, vitamins, and if you choose, supplements.

This is my ppm schedule for hydro:

Veg
Week 1 - 3-400ppm
Week 2 - 4-500ppm
Week 3 - 5-600ppm
Flower
Week 1 - 6-700ppm
Week 2 - 7-800ppm
Week 3 - 8-900ppm
Week 4 - 9-1000ppm
Week 5 - 1k-1100ppm
Week 6 - 11-1200ppm
Week 7 - 12-1300ppm
Week 8 - 13-1400ppm
Week 9 - Flush twice

These are day 1 of each week of fresh water with nutes ppm's. After two or three days, you should see a drop in ppm's after topping off your res. This means that your plants are taking in the nutrients you are providing to them. If the ppm's are not dropping, then they are drinking more water than nutes. (Another reason to know ppm's) If they are taking in nutes, it is up to you if you want to replace those nutes with more. If you do, you want to break up the nutes to measure up to the amount of fresh water that you topped your res off with. If you want to let them take in more, that's ok too. Keep in mind that the less ppm's, the more root development you get. This is because the roots grow out to find the nutes needed.....

If at any time you see your plants acting like the next weeks nute strength is too high, signs of over ferting, remove a couple gallons and replace with fresh water to lower ppm's.

Reason why you want to use RO water is to have every PPM accounted for. With tap, you get what the water treatment plant puts in it that makes it safe for human consumption. Depending on your area will depend on what the ppm's from the tap will be. Example: If your tap water has a ppm of 250, that's 250 ppm's of space that could be used by micronutes.....

Does the tds meter you are looking at read more than just tds???

CGI::::::