pH problem. Advice needed pls

[WNC Bonsai]

And you could be correct. I always wondered about the 1/2 tsp per gallon thing. That does not seem to me very much of the product.

Apparently it is very concentrated. As I remember folks used to have issues with it precipitating in the bottle and required a lot of vigorous shaking before use. However this bottle I have been using this summer has never done that so I assume they fixed the problem.

 

[Glaucus]

The product I have is a Birchmeier Aquanemix. I just calculate the concentration I need to put in there. Then I measure what comes out of my water sprayer with an EC meter, to confirm my calculation. And I then assume those values stay about contant until the reservoir empties.
I mainly have it to pray nematodes against cockchafer grubs. Not sure how well it would mix acid and hard high pH tap water, though. But you could use it to fertigate. Especially if you have low TDS water. There must be cheaper products that help you automate mixing stuff into your tap water than a 500 USD thingy.

Municipality tap water reports are often available online.

For liquid fertilizer, about 1 gram per liter is a pretty heavy feed already. If you decide it is worth the manual labour to fertigate, I would use a low dose. Especially if your tap water is already 'dirty'.
Especially if you can slowly dose in fertilizer automatically. But it is only worth it if you have many bonsai/plants. Better to apply a lower dose more often. And if you can also adjust the pH while you do it, even better.
Half a tablespoon would be about 8 gram? And a gallon 3.8 liters. Yeah, I would say 2 gram per liter is something ideal for heavy feeders like tomato plants. May be ok for bonsai in substrate. But I'd be careful with bonsai in soil. Especially when it gets hotter. I'd rather be on the lower side. Especially if you also combine it with slow release organic fertilizer.

 

[Paradox]

The pH of my water is around 7.4-7.6. That pH is slightly higher than neutral. I have never really had much of an issue using this water.
The only thing I do is use fertilizer for acid loving plants on those plants that prefer a bit more acidic conditions. Those plants seem to be happy with that.

 

[Glaucus]

Also, if you do have an irrigation system, be it drip or spray, and you have very hard water, and you use fertilizer, your system is going to clog eventually.

 

[bwaynef]

After 18 years of frustration with pH and what it means or doesn't mean, it now seems that pH has little to do with nutrition of plants growing in containers! ... The fiction about pH and the containner system is further confused by publications which claim that micronutrient availability decreased as pH increased. It is true that available iron and manganese decreased as the pH of the container growth medium increased. However, it is false to say that the pH level decreased the availability of iron and manganese. Peterson added increasing quantities of calcium hydroxide to raise the pH. It was, in fact, the increasing quantity of calcium that caused the decreased availability of iron and manganese; increased pH was merely a symptom. The pH increased du to the calcium but to blame the pH for the decrease in micronutrient availability instead of the calcium is an error in the interpretation of the results of the experiment.

I butchered the quoting, but that's from his book Plant Production in Containers. Considered by many the Bible for nurserymen. Its out of his research that Rootmaker pots came, and possibly the Micromax micronutrients that are popular today.

Anyway, I went on a bit of a tear researching and came across that (while trying to diagnose some chlorosis on a pine that got overwatered a few weeks back). I believe this likely means that some of the nutrient availability issues I cited earlier may indeed be from bad interpretation of data of an experiment.

Looking back at your original post, it seems the issue you're chasing is fungus. Have you had samples tested by a lab? Extension offices do that for you. That may get you closer to finding the source of your issues.

 

[Glaucus]

Availability of one nutrient very much depends on the excess of a similar one. For many nutrients, plants can't specifically grab one and not the other. So yes, some nutrients become more available at a certain pH can cause deficiencies in another.
This is pretty well understood. Calcium is one of the nutrients that is hardest for the plants to pick up. Which is why the other video commented on it. With acid loving plants and iron, the same is true. It is not that the iron is not there. It is that acid loving plants are extremely lazy in trying to pick up iron, because at the pHs they grow at, it is readily available and they would get too much iron and manganese. So they don't. Which can then cause deficiencies if they are grown in higher pH soils.