Curling tips = nutrient burn?

[happynoodleboy]

Here's where I'm coming from; last batch of plants I harvested had problems with nutrient burn. I was using 30 to 40% strength GH flora series.

The first symptoms I noticed before they got bad was curling, browning tips. I'm now running 20% and the leaf tips are just starting to curl.

Today I put water with no nutrients into my DWC bubbler. I am trying to keep my ph around 5.8 - 6.0. I'm using a TDS pen to monitor my PPM. The tap water has around 200 PPM and I have been adding around 300 PPM with the nutrients. I used this great post as a guide line and figured I was way below the concentration to burn --> https://www.rollitup.org/newbie-central/937-how-grow-marijuana.html#post4677
Am I not understanding TDS and nutrient concentration correctly or maybe my plant is just sensitive? The environment is warm at 22C (71F), with constant air circulation. Anyway, I appreciate any helpful input, thanks!

 

[snoopydoggydog]

Would be great if next run you could have two seperate bubbler systems in their and run one lower and one higher and see which one ends up being the best....

 

[snoopydoggydog]

I don't really know PPM

Can you tell me what that is in E.C ?

I don't really understand why people use PPM as it's not standardised like E.C is... like it depends on what meter standard you use 0.5 or 0.7 or something right.... Where as E.C is always the same across all the meters.

 

[70's natureboy]

You are looking good so far. The first pic was definitely a miscalculation and was way more than 300 ppm. To keep it simple just make sure your bottom leaves don't turn yellow from under feeding and your top leaves don't eagle claw from over feeding. If you go heavy on the P and K with bloom nutes the rusty leaves can sneak up on you. Just watch them closely and learn to read what they want. I think they could handle 6-700 ppm's , just watch 'em.

 

[happynoodleboy]

Can you tell me what that is in E.C ?

You know I have yet to learn about E.C. Thanks for tipping me off. I'm going to educate myself. I don't have a meter to measure it yet...

And thanks Natureboy, I will note the difference between top and bottom leaves, and keep and eye on P and K during bloom because that is when the rusty claws really showed up.

 

[1itsme]

some meters use 700ppm = 1 ec, some 500 ppm = 1 ec. it can cause confusion. the ppm reading is just an estimate based on the ec.