Sure, I'm trying to be as detailed as I can.An excess of calcium blocks the uptake of potassium and magnesium (manganese too), so that's a possibility. Something @Emilya mentioned in another thread is that too high or low of a pH could cause nutrient uptake problems as well. She recommends varying the pH between limits.
Magnesium deficiencies take four to six week to show up, so that's on the table. So is an excess of calcium.
Can you remind us of the pH, substrate, and nutrient concentrations you are using? That should help identify the culprit.
My soil is Plagron LightMix. It's a quality substrate with the following characteristics:
Peat moss, perlite.
pH (H2O) 6 - 7
EC (mS/cm) 0,7 - 1,1
NPK fertiliser (12-14-24)
It does have perlite mixed in it, but I added more, 5l into 25l of soil.
My tapwater is normally 7.0+ pH. I don't have a ph pen, only ph strips and a liquid hydroponic ph kit, so I can only guess, but it should be around 7.4 based on the amount of vinegar I have to add to bring it down to 6.7. With the same amount added once more, it brings the water down to around 6.0, so that's where my guess comes from.
I varied the ph of the water pretty much. Not really on purpose, but since these kits rely on color, I can't be that precise every time. I usually aim for 6.5. Sometimes it lands around there, other times the strip is darker than it should be on 6.5, so I add more vinegar, and end up around 5.9-6.1. In the first ~2 weeks I didn't ph my water, then I bought the strips and ph-d it every watering.
Yearly water reports for every household are not a thing here, but I requested it from the water department, they had info on the particular area of the city where I live. They reported that my tapwater is between 510-550ppm, with 23-26mg/l of Mg and 85-90mg/l of Ca in it. As I mentioned in the post above, I always used tapwater, sometimes with nutrients added, sometimes only pure tapwater.
I have to admit, feeding was a bit inconsistent. I didn't add any nutrient to her in the first two weeks, when she was a seedling. Then after that, which was about 5 weeks ago, I started fertilizing. Unfortunately, I haven't really kept notes (apart from this journal) about feeding, but I mostly remember what I've done. In these 5 weeks, I watered her 7 (or probably 8) times, from which only 2 times was only tapwater, on the other occasions, I mixed in some nutes. I go exclusively with the BioBizz line, it's 100% organic, and it was pretty expensive. I bought the smallest available bottles, and the whole package cost me around 50-55$.
Here's what I have, with NPK numbers:
It's a Dutch sugar beet extract, I used it almost every feeding (I believe there was only one time, when I used FishMix, and haven't added any BioGrow). Usually 2-3ml/l went into the mix.
Quite similar sugar beet extract with extra fish emulsion. The first two feedings, I used only BioGrow, since then I used both together. Similarly, 2-3ml/l when mixing.
Used it twice, last two feedings. I was pretty light with it, only added about 1-1.5ml/l if I'm not mistaken, but one time I was quite drunk in the morning, while watering.
It's a stimulant with humic and fulvic acids, meant to be used during flowering. Only mixed it in last feeding, 2ml/l.
A cold pressed seaweed extract. Apart from the first two feedings, I used it every time, and I was pretty generous, usually added 4-5ml/l to the mix. I also used it twice as a foliar spray.
Another additive, an aloe vera extract. I don't have an NPK value for this one. BioBizz claims,
Acti·Vera has been designed to protect the immune system, increase metabolism and enhance nutrient absorption in all sorts of plants.
I don't know if it does anything beneficial though, or it's just good marketing. Due to it's disgusting smell, I used it only one time for feeding and another time as a foliar spray, and put it away since then.
The recommended amount is 4-5ml/l of every of these nutes and additives.
Good to know, Penny!Understand that calcium is usually considered a macro and at times is the second most used nutrient. Most cannabis strains have an insatiable need for calcium.
Now, as I dug up another thread, that I posted before I started this grow @TorturedSoul and @farside05 also mentioned something about it:
Calcium seems to be the second most important element after nitrogen to cannabis plants (and to plants in general; they probably use more of it than they do phosphorous).
Today I took a day off from work, I'm going to flush with ionised water now. When I'm done I'll do more research on deficiencies, but right now I feel like it might be magnesium.
Thank you guys for all of your help so far!
If anyone has thoughts about this issue and a solution for it, feel free to share it!