PPM Level using Fox Farm Nutrients?

[deadlysars]

Hi,

First time DWC growing. I'm using 27 gallon tot with reverse osmoses water.

The fox farm nutrient chart for week 1 calls for 700-800 PPM. I fed my girls about 15 gallon worth of nutrients and my PPM is at 125. I figure since im using RO water my ppm started off at 1 so going to 700 PPM seems over kill or even 350 PPM seems a lot.

Thoughts?

 

[Moe.Red]

I do not use Fox Farm, but if I ran my RDWC at 800 PPM I would have ash where plants used to be.

The main problem with saying XXX PPM is what you need, is there are different scales, and different grow styles. I'll assume you understand the scales part.

When a proper hydro system is in full swing - you can pull gallons of water per day into the plants via respiration. The plant expects that you have the nutes at the right PPMs for whatever the respiration rate is they have high or low. If your VPD is off, you may pull more or less water into the plant. If you are really cranking using high PPFD and CO2 like I do, I often have trouble keeping up on the dehumidifier. In my 4x8 I can pull 10 gallons a day out of the air.

If the PPM of the water was 800 - that would cause nute burn in no time.

So really, the question should be what is the respiration rate of my system and back into a PPM number based on that.

If you don't know and can't figure it, start at 300PPM all in starting with RO (700 scale) and work up to max of about 400 if your plants are growing fast. This required close supervision of the plants daily until you get it locked in.