What levels should I maintain for my hydroponic nutrient, temperature, pH and TDS/EC?

I follow and highly recommend the following parameters for hydroponic nutrient solutions for aeroponic, ?bubblers?, drip, ebb and flow, NFT, passive, rockwool and wick systems.

PH 5.1-5.9 (5.2 optimal)
TDS 500-1000ppm, EC .75-1.5
Temperature 68-78f, 20-25c (75f, 24c optimal)

The pH of the nutrient solution is a major determinant of nutrient uptake by the plant. If the pH wanders outside the optimum range of between pH 5.1 and pH 5.9, then nutritional deficiency and/or toxicity problems can occur. For hydroponic nutrient solutions used with inert media, keep the pH at 5.2 for optimal elemental uptake. It is at this point that roots most readily assimilate nutrients. These pH and TDS/EC recommendations may seem low relative to the normally suggested range, but are based upon information garnered from “Hydroponic Nutrients” by M. Edward Muckle and Practical Hydroponics and Greenhouses. They both document the low pH resulting in increased nutrient uptake and my experience has shown discernible health and yield improvements at a ph of 5.2 over higher levels.

On page 100, Hydroponic Nutrients displays both the assimilation chart for organic soil applications and another for inert medium hydroponics, which depicts the vastly different scenarios (see below). The widely accepted soil based chart is frequently misapplied to water culture applications. His research and that done by others, documented in Practical Hydroponics and Greenhouses, indicate that iron and phosphorous precipitate in nutrient solutions at pH levels above 6. Stay below a pH of 6 by all means to avoid this problem and benefit.

The nutrient assimilation rate is further enhanced by the reduction in solution TDS/EC, which reduces osmotic pressure and allows the roots to draw the nutrients “easier”. Young, established seedlings or rooted cuttings are started at 500-600ppm. The TDS is increased to 800-900ppm during peak vegetative growth. During the transition from early to heavy flowering, TDS is further raised to 1000ppm. It is then reduced to 400-500ppm during the final 2 weeks of flushing. The plants demonstrate their preference for a lower TDS/EC when running a lower pH by clearly sustaining higher growth rates.

The optimum temperature for hydroponic solutions to be is 24c/75f. At this point, most elements are assimilated highest and atmospheric oxygen is most readily dissolved. Although increases in temperature increase the rate of photosynthesis, avoid exceeding the maximum listed of 25c/78f. Elevated temperatures make some elements more available, but reduce the solution’s dissolved oxygen capacity, increasing root disease likelihood.

Nutrient Availability Chart

is this book about Marijuana or vegetables? 5.2 does seem awful lowwwwwwww. I try to stay from 5.5 to 6.2ph and I usually don’t have any problems.

Numbers I find good for my plant, YMMV

For RO :

Veg 350PPM-500PPM
23c
PH 6.5

bloom 500PPM-700PPM (ramp up as time goes on)
21c
PH 5.5-5.8 (let go to one end then adjust back to the other end)

Add 1/2 of your tap water’s PPM to these numbers if not using RO.

I feel that the numbers in the OP above could be more fine tuned to our particular plant…

Another chart for information…

I have found a sweet spot at PH 5.675 -5.7 but you need to keep your PH regulated to a range of 0.025 to fully take advantage of it. Much easier to allow your PH to wander through the range of 5.5-5.8 then adjust it to the other end and repeat. This would mean you do not suffer ill effects from the lockouts of zinc, magnesium, and manganese.

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