Nutrient problem! NPK, EC, PPM

Ok so first post... Excuse me if I sound like an idiot.

im not new to growing, but never ran a hydro system. Been doing lots of research about hydro and only have one question left unanswered. Not even sure how to word it lol, but here goes;

when you make a mixture you set your ec/ppm to a certain point e.g 1.8/1260 or whatever it may be...
now as your plants feed your ec/ppm as I understand, will diminish. So when I comes to topping up your reservoir, how do you know what specific nutrients to add?? Does this make any sense?

ive never had to top up a mixture only make new ones...
I generally use canna coco nutes, and including the A and B it's a five part mix.

so how would I know which of the 5 to add to take my ec/ppm back to desired levels?

again apologies for newb question, I'm sure there's a fairly simple solution I'm just not grasping.

Thanks

Some use a 50% top off.

Others float top with RO and dose by hand using EC measurement and calculated addbacks. Document effects of a light addback and you can multiply that as required to get target bump.

Hydro cheat sheet:
Ec/PPM goes up, PH goes down=plants require less nutes.
Ec/PPM goes down, PH goes up=Plants require more nutes
Ec/PPM stable, PH goes up=Equilibrium=Good thang.
-OldPhart
This may help you out.






Indica's
Seedlings and clones 300-400ppm 5.3-5.5 ph
early vegg 500-600ppm 5.3-5.6 ph
middle vegg 600-800ppm 5.4-5.6 ph
late vegg 800-1000ppm 5.5-5.7 ph
early flower 1000-1300ppm 5.5-5.7 ph
middle flower 1400-1600ppm 5.5-5.8 ph
late flower 1000-1100 cheat sheet

Excellent! Thanks for quick response... So what your saying is, if I need to add more, add a little bit of everything at usual ratio until desired level?

Doniawon: thanks for that "cheat sheet" that's a great little bit of knowledge to have!

I just addback base nutes and calmag.

Cool man, thanks

An easy way for beginners to do hydro is to use the 33% rule of add back.

Like this. Fill your res with the makers feed chart for your amounts at 100%. As the tank needs to be topped off, do that with a 33% feed solution. (make 1 gallon of full strength nutes and add 2 more gallons of straight water = 3 gallons of 33% solution.) Top off the res like this UNTIL you have reached the same amount you put into the res in total. DUMP res and refill with 100% solution and repeat.
This is fool proof and works great until you may refine your own way. If you use RO water you MUST add a Cal/Mag product at the 5ml per gallon rate. To start and at the 33% add back from then on until res dump.

Good Luck

Thanks for that man, all good advice.... Think it's dwc time, seems to be the way forward ( although been having great results it coco with normal watering through pump and lance but wanting to cut down plant numbers and speed things up!). Open to suggestions though if anyone has any other ideas?