rez changes.... how important???

Got some bubblers on the go, plants seemed ok, nice an big with fat stems, tallest is about 5ft 5" now, some signs of deficiency showing now 3 weeks into flower, leaf edges yellow and some yellow/light brown patches between viens on some leaves.

I was completely emptying rez regularly but now they are big and very heavy its too hard to change out properly (basically square storage boxes with holes in the lids, similar to rubbermaid ones I see others using), anyway, i have just been letting the 10ltr rez get almost empty and simply filling right up every 2 days (they r slurping approx 2 or 3 litres each plant each day), only thing is the ppm is very high, just took a reading of 3500 so im guessing this is really bad considering it should be around 800.

Any ideas welcome.

brief rundown.
RO water
canna nutes, aqua flores A+B
ph usually good 5.8 - 6
air temp 85f
good air flow
2x 600w dual spectrum bulbs using digi ballasts.

you are going to have to either change the rez or stop letting it get so low cause you are letting your roots sit in super concentrate of nutes after they drink up all the water.

...is your ppm @ .7 or .5 conversion? 3,500 ppm??? wtf???? Your plants should be dead....

Not sure about the conversion thing, it's a digital stick with an LCD display on!

Before I was puttin nute mix in, then next time just plain ro water, should I just top it up all week with water then nutes at weekend?

Thanks for the replies

...I'd top it daily myself...or atleast check the ec/ppm and ph. Ever heard of the lucas formula? A very good read for ya here ....Check it out >>> https://www.rollitup.org/hydroponics-aeroponics/338720-lucas-formula.html

Thank you, I shall top the water daily, if I follow the Lucas formula u directed me to I will do 3 water and the fourth day nutes.

I have 4 rez's with 2 plants in each, I got 2 down to 1500ppm and the other 2 down to the more acceptable 850ppm, I will see how it goes over the next few days!!!

i agree with the others.... keep your water from half to topped off. i feel that the extra air is sometimes good for the plant half way down, but never empty with that high of a ppm. in don't res change till flush. i just add water and nutes through out the cycle. i think it a way for he companies to make more money.

Thanks again for the tips.

Just a quick update on ppm reading, I use the canna calculator on the website and it asks for ppm type and always selected Hanna, and once mixed it was always very close to what the website said it should be so I guess I picked the right option!!!

i know of this situation (plus the whole fact that when you try and get the res out all your plants start falling everywhere)

like poeple say, seems like there is a lot of money grabbing involved (considering the price of things like canna boost, i feel very guilty pouring water down the sink. i find that once mine get's to about 1/5 full the EC is sat around 5.5-6 which isn't too dandy so i've taken to the LUCAS Formular (not sure why it's got it's own name and it's a formular and such or whether i just do it wrong, i make up some feed and chuck it in with the other water and make sure the PH and EC are not whacked hardly a "formular").

https://www.rollitup.org/dwc-bubbleponics/349573-plant-not-taking-up-water.html

This is a thread of mine which sounds remarkably similer to your problem.
I have had exactly the same symptoms that your describing except mine are at week six and a lot worse off by the sounds of things.
I have had high ec ratings like yours, they where drinking 4-8 litres a day and nearly emptying the tub what with the rootmass, leaving me with high ec.
The yellowing of the leaves is a bit more servere in my case also mg type deficiency in leaves i.e green veins yellow inbetween.
i think this might be lock out due to the high ec iv had and why they arnt taking nutes im changing the rez at lights on (8pm) for a fresh one. ph and ec perfect.
hope this sorts it out, good luck with yours buddy

Thanks for the tips, but i think i have it under control now, i decided it would be beneficial to fully change the rez regurlarly so i use a little submersable water pump to suck all the manky water out, this is very easy compared to physically lifting these huge heavy plant up and trying to swap the rez over like i was doing, i just top the rez every day or 2 with pure RO water then fully empty and replenish after about 4 days (as suggested to replace properly once u add the same amount of plain water the rez can hold), they look pretty good now, with 3 weeks remaining, a few have hit 6ft tall now and r out of control, i have 8 biggies in a 1.2 x 1.2 x 2m tent, the cooltubes r 1 inch from the roof and the top of 2 of the white widows r above the light beams, its alot of plant to cram into a small area but ya live n learn, i will just do 6 next time and not veg out for quite so long.
I will post my yield results in a few weeks for those who may be curious to know how they did, and seeing as this was my first bubbler attempt im hoping for some good results!!!