Erp... apologies for the out-of-time reply above. Great to see you got the perlite happening, not great to see the overfeed. Here's the thing.... SIPs are even more efficient at fertilizer use than DWC, as w/ dwc you dump out the uneaten every week, with SIPs it remains in the matrix and gets used. My elemental breakdown (usable ppms only) is 150ppm N, 32ppm P, 120ppm K, 150ppm Calcium, 50ppm Magnesium, plus micros, in veg. That's a pretty low feed, it reads 1000ppm on my 50 scale bluelab pen.
There is always the possibility of nute retention causing toxicity when feeding in this passive manner and the risk rises with feed ppm level. When I think of SIPs I personally think that the comparison we should be making is not with DWT but with high-frequency feeding in coco or peat. HF feeding usually has small pots - 3-5 gal and feed is dripped through 5-8 times a day or more. This constant newly arriving feed is exactly the scenario we set up when we use a SIP with heavy aeration (perlite). With perlite, the capillary action speeds up tremendously, constantly delivering new nutes to the plant. Provided this flow continues we've created a constant-feed scenario and I think its to HF feeding we should look when having issues.
As for the reservoir, I have some issues with how you've built but in order to illustrate my point I'm having to search around for some pics or it wont make sense. Also, my keyboard - of all things - gave up the ghost and I wasn't able to reply for a few days until my new one arrived. I just cant do 420 with my phone either, in my present condition (broken ribs and a scratched cornea) but I apologize nonetheless for the delay. Please be careful with those percs mate. I've been in recovery myself for over two decades now but I still have to respect the fact that it will take next to nothing for me to fall off that cliff again.
I really recommend the MC over the GH Maxi products. I use both extensively and always prefer the MC (mine is the two part). MC uses amino acids to chelate the micros and this is much better than the EDTA and other synthetic chelates GH uses. GH Maxi is also much less pH stable than MC in my experience. Lastly, the results of an overfeed with Maxibloom have been more damaging than when I've overfed MC. I can also feed a higher ppm with MC than I can the Maxibloom which causes burns and issues at much lower ppm. MC also has some Silica and magnesium already in it. I raise the Mag with 1 gram/gallon epsom.
With my 2 part MC, to make 20 litres (5 gallons) I mix 12 grams part B (calcium nitrate), then 5 grams Epsom salts, two crushed 300mg Aspirin, then 20 grams part A - the 5-12-26 fert. I also add some liquid seaweed, humic acids, and a cap-full of my lovely liquidirt in the mix. These biologicals are added very sparingly as I don't want them to go off in the rez. I have airpumps/airstones in my reservoirs again for latest grow (GG#4), on pulse timer 3 minutes every 30 minutes.
I do a litre (quart) of mixed bennies and mycs once per week that I add from the top. To make I put a mason jar /litre of distilled water on my lab stirrer/warmer plate for 48hrs with added microbes (NPK brand phosphate solubilizing microbes, a scoop of septic tank treatment bacteria, worm castings, liquidirt, humates, Humboldt's Secret Golden Tree and either some brown sugar or molasses, sometimes bean or rice flour too). In my 7-gallon planters this amount does not leach anything to the reservoir, it soaks up all of it which is what you want. Also, I delay these bennies until the plant is mature and the roots well developed so I don't mess up the moisture gradient which is especially important during the developmental period so as to be sure hydrotropism takes place.
Lastly, it sounds like you just mixed your mycorrhizae with the soil, when in fact the best practice is to generously put it in the transplant hole and onto the wetted rootball during transplant. It needs to contact the roots to begin colonizing and there need to be enough spores directly touching for it to build out effectively.
omw lol!