How high should PPM be?

I have 24 clones that range from 9" - 12" tall. They are growing in hydroton in a ebb n grow system and are being watered every 6 hours. The clones were cut from the mother plant Dec 20 and took about a week to root. I have been vegging them for about 16 days now. My question is how high should the ppm be for plants that young? I just had the nutrient solution around 550 ppm all last week and they didn't seem to be drinking the nutrients because the ppm stayed the same all week. So at the moment I have clean ph water with no nutes in the reservor as of yet. Im not really sure if I should do more of a mild nutrient solution or increase the ppm high then I had it. Any advice would be greatly appreciated. Here are some pictures. Seems that they are deficient in something. Im not really sure if it is from the ppm being to low or high. Also, I have been have problems with the ph. Everytime the plants water the ph jumps up to 6.5-7.0 and I always have to adjust it back down to 5.6-5.7. Please help!!

Because the ppm stayed the same doesnt mean the plants arent eating. There could be salt building up...but the plants could still be eating. They eat some....then salt builds...and the ppm stays around the same.

Sounds like you're flushing...good idea...dont go too long on the flush...a day or 2 tops is all thats needed.

If your plants werent burning...go back to the same nute strength you were using. They grew that well with that nute strength before....so they should continue to do so.

They may even ask for more than that after the flush...but stay on the safe side...You can always up your nute strength later on.

And make sure your ph is in range.....If they cant access the nutes...They cant eat.

BSIv2.0 said:

Because the ppm stayed the same doesnt mean the plants arent eating. There could be salt building up...but the plants could still be eating. They eat some....then salt builds...and the ppm stays around the same.

Sounds like you're flushing...good idea...dont go too long on the flush...a day or 2 tops is all thats needed.

If your plants werent burning...go back to the same nute strength you were using. They grew that well with that nute strength before....so they should continue to do so.

They may even ask for more than that after the flush...but stay on the safe side...You can always up your nute strength later on.

And make sure your ph is in range.....If they cant access the nutes...They cant eat.

Click to expand...

That's the thing. The PH wont stay in range. It keeps going way up after each water. So....I think there must be a nutrient lock out. This is the second time I have done a flush. Last week I flushed for 2 days and added nutrients back in. I don't understand why my PH won't stablize

Hello - you may want to have a look at this thread:
https://www.rollitup.org/hydroponics-aeroponics/41552-ppm-question.html

my grow journal has very detailed info on my grow - warts and all!

how much of that rez are you using? is it full? i'm sure it has an air wand in it right? plants that age/size should be getting more than 500 ppm. they may need more food. i don't think you have to worry much about salt build-up since you're in a recirculating system.