I have read a lot of material here on the forum and recognise that that there is a wealth of information available here so many thanks to all of you for such valuable data.

My question is as follows:

In a full hydro system, ideally there is a balance between the level of nutrients in solution and the take up of water by the plants, such that pH stays ideally around 5.8 as the water uptake balances the nutrient uptake. Of course, extraneous factors such as air temp, air circulation, whether you are running a dehumidifier to maintain optimum Rh, level of maturity of your plants etc all contribute to the loss of water in your tank.

In general it seems to me that, putting the above to one side, pH tends to increase over a period of time. I read this to mean that the uptake of nutrients is higher than the uptake of water. Consequently the pH increases (as nutrients tend to reduce the pH), and for those who do not use a conductivity meter, pH adjustment down is necessary on a regular basis.

If we assume that the rate of change of growth on a weekly basis is reasonably minimal, could we use the rate of pH increase as a trigger for the need to increase nutrient strength at the next change, particularly if you are using 1/4 or 1/2 strength solution during the early weeks?

Hi


Not reliably IMO because you'd end-up...

...

As your third parag. suggests, even a simplified growing system is dynamic,complex & non-linear... there's a few factors at play and things can quickly become chaotic.

My pH consistently drops - I've never established why that is, nor has it caused any significant problems...

Many peeps use a nutrient meter as a direct measure of solute concentration, others play it by ear or follow the nutrient schedule and get good results.

That having been said, if the pH of your solution has swung over 5 or 6 days (and the EC has remained constant) it's probably best to change the res. anyway.

Hope that helps...

Stan