Well I'd hate to talk on behalf of cruzer, but I'll give it a try..
When growing hydroponically you can use a ppm meter to measure the strength of your rez. right? What he does is to lower the ppm of the rez. and keep checking it daily. When he notices that his plants are using up all the nutes he'll add more (cause they're still growing).. if he starts to notice that the ppm is not getting lower as quickly as it used to, then is when he should also start lowering his nutrient strength and when the added dosage is so low and the plants are still not using everything, this should be the right time to cut cause there's no more growing left.
During this process the reservoir should be flushed on a weekly basis in order to keep the measurements correct.
Hmmm I hope that was explained correctly..
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Close, but no bananna
We were talking about removing stored nutrients in a plant at the end of its growth cycle.
Durring a plants cycle if ph is correct the plant will use the nutrients and expell plant salts. Nutrients are salts so both are measured together with a PPM meter.
Plants use water and nutes. The plants give off salts too and you cant measure the difference between nutrients and plant salts its all PPM.
So as your water level goes down you want the same PPM. Its going to rise so you add water then ph. once you have added the same amount of water as the res holds over time its time to start over. This is why it is recomended to change out your res with new nutes, to get rid of the plant salts.
Once you get good at it and your plants are absorbing the nutrients as the water level lowers the ppms lower too! Then you add nutrients when you top off. Now your growing!
When plants are small they use a hell of a lot less then when there monsters. I go two weeks easy when they are young. On the other hand middle flower in the summer I change out twice in a week. Plants use more water and I run a 6 gallon res.
It's constantly changing, If the Ph is off the plants don't use as much water either. If humidity is to high or they don't have enough fresh air (CO2) they cant process moisture and dont use much water. Funny thing, if that happens they expel more salts and your PPMs go up and its like WTF? LOL
So after I top off with six gallons I change, That way I know my PPMs are nutrients not plant salts.
