Strong nutes and PPM? How to understand? Need serious help

[DaTrueWhiteMa]

Ok im confused..I started flowering like 3 weeks ago,plants were veged for 10 weeks but they had alot of stress so they are like normal grow 5 weeks maybe I guess,first grow..So Anyway,week 3 flower,there wasnt much to choose in store for flowring type so I got NPK 20-40-40,5ml to 1 liter of water..Now I dont understand one thing,so I was thinking im gonna need to use 4x times less nutes to be it like 5-10-10 or 10-20-20,so I put like 5ml (1 liter dose in the 5 litre bottle I use ) and look at PPM,my stock ppm is like 300,so with 5ml added I had like 400 max,so I was like wtf,ok I added 2x more,so thats like 66% of the dose,my PPM was like 600 max,so full 5 litre bottle was like ~13-26-26,so I was like how in earth 13-26-26 and only 600PPM? Last nutes I used was like 3-7-4 and giving full dose was like 1k PPM+,how 3-7-4 PPM is higher than nutes that are freakin 4-5x times stronger?? How many of the nutes I should give a plant,and what do you think,I gave my 13-26-26 dose just today and im starting to think if it wasnt too brutal overdose,they didnt have strong nutes for some time since I had N overdose..but I didnt have normal nutes for about week or even more,was watering not very often lately,maybe I should skip now like week without watering and then one only water watering and then more like 10-20-20 dose? What would you suggest.Btw 600+400w hps.

 

[Hiddenkoncept]

Try 10 20 20 and see how that goes, you can always adjust ppm by adding more water to bring levels down.
I'm often confused by ppm and how they can range up and down sometimes...make sure you give your nutes a good shake before hand and give your solution a good mix.

Also I know it's obvious but make sure your meter is calibrated .

Hope it works out for your mate.