*UPDATE*
We just checked them and we are still seeing yellowing. The following is our feeding schedule:
1.) We started to see yellowing so we fed them 10ml/g (the recommended dose is 25ml/g)
2.) Two days later we noticed the yellowing was persisting so we fed them 20ml/g
3.) Two days later the same thing. We upped it to 25ml/g.
4. Two days later the same thing. We upped it to 30ml/g.
5.) We just checked them and the yellowing is still present. Even more leaves than before. I guess we should just keep upping the dosage. I guess next will be 40ml/g. The top of the plants and buds look beautiful but these lower leaves are really yellow. Some are dying off.
6.) *2nd Update* More and More leaves are dying and falling off. I really need to up the feed dramatically it seems. Perhaps feed them daily instead of every other day.
Are we talking just a few yellow leaves? The close up is on just one part of the plant and it's hard to see the plant as a whole.
I'm getting the feeling there might be no deficiency issue.
Healthy plants do throw off the odd yellow leaf.
The pH debate - here's my take
* IMO run off pH run off or pH is meaningless. I've seen a fair few growers ruin their grow based on run off pH and EC. The concentration of soluble compounds is so variable it just doesn't work. That's my opinion.
* If the pH of the medium is correct, adjusting the pH of the nutrient solution is pointless, because the soil acts as a buffer. If you (when I say 'you' I mean anyone reading this) don't know what a pH buffer is then Google it, but it compensates for a high
or low pH in the feed.
If it did make a difference, then why does it make no difference when I water with acid rainwater compared to tapwater with a much higher pH (sometimes the difference is as much as 300 times the difference in pH?).
It's the pH of the medium
itself that counts, not the water/feed that's used on it. This is why you can't grow health plants in just pure peat moss - you need to add dolomite lime or even garden lime. However pH issues inherent with the medium itself cannot be fixed by changing your feed pH. To do that would take far longer than the life cycle of the cannabis plant.
Ever see grows watered with rainwater, and how they flourish (even more than tapwater grows at times)? Do you know what the average pH of rainwater is? Usually around 5.6 in my area at the moment (although variable). If pH were such an issue then gardeners collecting rainwater in water butts to water their pot plants would have started noticing an issue.
Growing in soilless mixes is not like growing in coco or other passive hydro media at all. In all these, adjusting feed pH is critical, but with soilless media it's the pH of the medium itself that's important, not the feed. Of course people very frequently grow in coco, perlite/vermiculite, fytocell etc. where pH adjustment is essential, and so naturally assume doing so is beneficial for soilless mix media. But this is incorrect and they make this mistake because they have had little to no prior gardening experience.
And just a cautionary warning - you should never use dolomite and fertilizer at the same time. Dolomite lime really should be mixed into the medium when it's made and left to settle for a few weeks at least before use (more time that with garden lime). Getting the proportions of dolomite to potting media right requires knowledge of soil science and how the ingredients interact and really is best left to the soilless mix manufacturers who have the process automated to a degree, to get a consistent product.
Wise et al. please don't take this personally. I think we've realized that we can disagree about these things and not take it the wrong way, but I really do disagree with a couple of the points you're making. Fair play to you for trying though, and it's all about a collective learning experience. I'm not always right but on this issue I'm pretty sure. It's good to debate these things without it turning into an ugly flame war as it happens so often on other forums.
Spanso, one thing you
can do, regardless of the pH issue, is to change to a quality organic fishmix type fertilizer (it's not too late) instead, like Biobizz fishmix and use it on at least one plant. If you try different things with different clones (remember, iirc, they're all identical clones of the same plant and should behave very similarly, meaning experimenting is more meaningful) then you can work out what works the best.
It could very well be that the feed itself is shite. If you don't want to listen to anything I've said about pH, then at least do yourself a favor and adjust the pH with
citric acid, since it's organic and is more appropriate for growing in dirt if it's watered in straight away and doesn't sit in some hydro res constantly. Adding phosphoric acid or nitric acid to lower the pH can add phosphates and nitrates to the (NP)K value of the feed, to a minor extent. Keep that in mind!
If you want, come back with 3 things:
- the pH of your plain tapwater straight from the tap.
- the pH of your feed at 10ml/gallon
- the pH of your feed at the highest dose you were using
But if the medium you bought was any good in the first place, they would have
already added dolomite lime to it to begin with. They should have mixed it in such a way that the pH is around 6.5 or thereabouts.