EC levels in res

[silent-toker]

hi all, ive started using canna coco in a run to waste set up and im making up nutes in a 25litre res at 1.8 EC and using an air pump for mixing and aeration. the EC level drops over the week that im using the solution so that its measuring only 1.2 EC at the end. PH is fairly constant 6.2-6.3

should i be adjusting EC?

have just begun this coco set up and still learning the deal so would appreciate any other advice about nutrients/ additives, thanks

[Stoney]

well i aint to shore but are you talking about ppm because if so your plants can handle up to 1800ppm befor they start to show some signs of nute burn. i usually start mine off at about 1700ppm and then keep a close eye on them everyday topping up nutes or water or both to keep it fairly close to 1700ppm as i can that way there is always a 100ppm buffer befor the plants start gettin burnie

so if this is what ya talkin about then yeah i would be topping up ya nutes to keep the levels up

hope that what ya talkin about if not disregard my whole post

 

:Dj:

[silent-toker]

yeah stoney thats what im talkin bout! ive got a bluelab truncheon which has EC ,CF and PPM. it has two ppm scales, one x500 and the other x700?? not sure which ppm measurement to read as indicated by the light so i go off the EC scale?? anyone help with using the bluelab truncheon??

 

Anyway, before i keep asking more unrelated questions

Why are the EC levels dropping? how often should i make up nutes?

[SukonmiSkunk]

I go by ppm but if you keep your ec at 2.0 at the very least it should be fine... yeah so just add more nutes.. the ph is sitting perfect...even a ec of upto 2.4 is acceptable.. some one who uses a ec meter might be ablke to confirm... but at least 2.0

why they drop.. are you vegging? obviously.. during the veg stage they suck the nutes more than water.. when the flower they suck more water than nutes..its just the plant sucking them up.. thats a good thing.. just top up the levels as the get too low...

[pipeman]

Man thats some super freaky plant to be able to suck the nutes out of the res in a run to waste system

[chippy]

Hi there [TOKER] i use a eutech waterfroof p,h & tdscan4, the tds meter is in [MS] MILLY SEAMENS, i run my girls at 18m/s or 22m/s for veg and 22m/s to 24m/s for flower , and it work well that is what the info i have read up on ,your M/s is a more presise mesurement i am led to deleive, thats what it tells ya in all the hydro books i have read , best of luck with ya weeds, your [PH ] is spot on , happy growen, may ya mull bowl be full, run ya clones around 12 to 14 M/s and as soon as they get roots bring your reading up to 14 to 18 M/s thats that all folks

[silent-toker]

thanks for the replies everyone!

not to sure whats goin on tho, could it just be solids dissapating or aerating the solution that drop the nute levels? ive only just started measuring stuff like ph and ppm/ec after growing organically in soil so its all new atm. ( stoked with the results so far)

i use 60mlA + 60mlB to get 1.8 EC then about 4-5 days later have to use another 15ml of both to get from 1.2 back to 1.8EC??

plants are healthy enough, just yellowing at the new growth a bit.

thanks again, S-T

[Roadblock]

The ec is the electrocoductivity of the nutrient solution , basicly meaning the amout of current that can pass through the nutrient , the more salt the higher the reading , to much salt you burn , my guess is when the tank is first made up the ions can hold thier highest charge or reading and if left sitting over time this will lower some what like a battery discharging .

 

Whether to add more stock to get the charge up to the correct gauge reading being the right move for the plant would need to be tested, because the plants natural varibles are outside the difference in readings over time , you probably have nothing to worry about , the plants internal varibles are not that precise unless you are near an extreme edge of the individual plants scale , thats why you are always better being on the weak side to being one the strong side with nutrient strengths .

 

A technical answer that may be a mile of the mark , something to think about anyway

 

Rod

[Luke Skywalker]

You could have nute precipitation perhaps? Is your tap water particularly hard?

My guess is when the tank is first made up the ions can hold thier highest charge or reading and if left sitting over time this will lower some what like a battery discharging .

 

Sorry roadblock, but that's not the mechanism. The nutrients are merely conductors, they don't supply the electricity, that's what's done by the meter.

 

If there's a significant drop in E.C. in your tank then I'd suggest that you've got some settlement happening, or something else is feeding on the nutrients. Algae perhaps? If the tank isn't lightproof this could be a cause.

 

Put a small pump, (like a 400lph or something) into the tank to just constantly move water around, keeping it well agitated.

 

Have you recently cleaned and checked the calibration on your truncheon? You can't adjust the calibration of course, but you can tell if it needs cleaning that way. If it's been a long time since cleaning, or you never have, then get some unscented jif (cream cleanser, and it has to be unscented), and with a clean finger just rub a drop over the electrodes for a couple of minutes. Rinse well under the tap, and if you have to remove any jif that won't come off under the tap use the same finger you cleaned it with. Don't use a toothbrush or anything like a scourer, just your finger. If the truncheon is clean it shouldn't bead water on the probe but form a smooth film.

 

It's an interesting conundrum you've got there, by rights a RTW system shouldn't have any nutrient drop after intially making it up. Ensuring you mix the solution well after adding each part of the concentrated nute should help reduce any possible precipitation that may occur if added too close together....

 

Let us know how you go...

 

btw, IMO don't bother using ppm, it's an inaccurate and sometimes confusing measure, as you've seen there are several sclaes for it and it's only a conversion rate anyway from e.c. Some may prefer it out of habit, but I've never had someone confused by giving an E.C. figure, but many have been confused if you give it in ppm and they don't use the same conversion scale as you.

[silent-toker]

yeah thats alot to think about!! I was putting it down to the nute salts/water/air sort of balancing out over a period and lowering the conductivity but was wondering if the actual strength of solution was lower

but if the EC is measuring lower then nute strength must be lower and going from others experience and stoners logic EC should only go up in the res as water evaporated or was drunk by the plants??

 

now that ive read lukes post its got me thinking bout 2 things

mainly the res isnt lightproofed and also when im using the nutes i have about 4-5litres left in the res and then ive been adding 20litres of freshly mixed nutes to that for the next week, only just started doing this

 

pretty easy too sort those out tho, will lightproof the res first and start with a fresh solution and use it all before making another.

will see how that goes and let ya know. - thanks for putting me on track guys ( if i am on track??, if its the truncheon i will fuckin spew, that thing cost me $120 only 6 weeks ago and i have rinsed it after every use, gets more care than the plants just about

 

p.s. just havin a laugh! if it was the truncheon i would take it back for sure, its just the right shape for shovin up his arse!!

Edited June 30, 2006 by silent-toker