Banana sativa

so I've been having issues where the leaves get tiger stripes , at first I thought it was nitrogen deficiency , then I was advised by someone in here to feed more call mag as it was a mag deficiency,I did this but it didn't change anything it just got worse :-( after reading many sites and getting very conflicting info I bought a narrow pH kit (drops) and double checked the pH just in case my pH meter was wrong (calibrated with ph buffer 7) it turns out that my pH meter was way out !! The pH was close to 8 in the soil so I'm guessing this is what was causing the issue with magnesium deficiency. I've been setting the nutrient at ph5.5 and running a 2litre run off every time but the run of is still coming out at 7.2 after a week of such low pH feed going in .(4litres going into the pot and 2 litres run off every other day) I was reading that you should use mag/sulfur after the first 2-4 weeks of flower as the plant doesn't really need calcium after this point ? and uses more magnesium and sulfer in bloom. I also read that using calmag with pk boosters causes the calcium and phosphorous to bind and become insoluble leading to deficiency's ? so I've decided to but epsome salt and use that instead of cal mag. I'm trying to teach myself but find so much conflicting info :-/ next time I think I may go all organic so I only need to water :-)