I am using Soil, Canna Terra Professional. It came at 5.8ph buffered strongly. I found this far too low and always believed soil should be more like 6.3-6.5. So i added lots of lime and flushed it heavily (recirculated the flushing water and adjusted the Ph as the water went down and the soil went up.
I just looked at Canna's website, from what I saw they don't sell soil.. The 'Canna Terra Pro' is the only substrate I saw and its not soil, its a peat based soilless mix, which would explain why the pH was at 5.8. IMO you changed the pH of the medium too high which would explain the deficiencies you are experiencing.
Canna Terra Pro mix came pH buffered with lime at 5.8 because that is within the optimal range of soilless mediums, i.e. peat moss and coco coir, for nutrient uptake. You thought it was 'soil' so you added more lime and high pH water which brought the pH of the medium within 6.3-6.5, which is not optimal for peat based or other soilless mediums.
You are correct in your line of thinking, soil pH around 6.3-6.5 and so on, but you are using a peat based medium and when the manufacturer uses lime to balance the pH to a specific acidity, like 5.8, don't change it, unless you know exactly what your doing when adding other mixes and/or amendments.
I understand it can get very confusing on what is soil and what is soilless, IMHO if there is no compost in the mix, then its soilless. Another thing, whether its organic or not, has nothing to do with being soil and/or soilless. Its all about ingredients, for example, Sunshine #4 has peat moss, perlite and coco as the medium, which makes it soilless, it also has lime and
yucca extract, but those are to buffer the pH and a wet the medium evenly, basically they have nothing to do with the definition of the medium itself.
Another example, here is the ingredients list of
Fox Farm Ocean Forest:
Ingredients: Composted forest humus, spagnum peat moss, Pacific Northwest sea-going fish emulsion, crab meal, shrimp meal, earthworm castings, sandy loam, perlite, fossilized bat guano, granite dust, Norwegian kelp meal and oyster shell (for pH adjustment).
Now if you look at the front of a bag of Ocean Forest, it will say 'Potting Soil', that is because it is a soil. The reason its soil is because of the composted humus, that in and of itself makes it a soil. There is peat moss in the soil mix, but it is an amendment, when peat moss and/or coco coir is used as the primary ingredient with other 'hydro' substrates, such as perlite, then they are considered soilless.
Basically, its the compost that makes soil, a soil, there are plenty of hydro/soilless amendments you add to soil just like perlite, but its still soil, just like Ocean Forest. Now if you use a hydro/soilless amendment by itself in a bucket to grow, like perlite, then its considered hydro. If you use peat and/or coco in another bucket by itself then its considered soilless.
IMHO, a soil medium should have a pH between 6.2-6.7, soilless should stay between 5.8-6.2, and DWC, (you know, straight H2O as the medium) should be around 5.5-6.0, depending on growth phase. Just my opinion bro, don't take my word for it and please do your own research, good luck!!