Newby confused about EC

Hi all,

I have been reading here for about a year but this is my first post.

I have a problem with the ec reading from a Bluelab truncheon and require guidance please. I have mixed up a 70 litre res for my hydro system with filtered water and a small amount of tap water to get the PH to roughly 6, the tap water has a ph of 8.0 ish and an ec reading of 0.3 -0.4 depending on the day, so pre filtering seemed a good idea rather than adding lots of ph down.

My problem is that the dutch pro label says add 250-350 ml per 100 litres of water. So to start off I was aiming for an ec reading of around .6 to .8 and added some nutes to the tank but after adding 80ml the ec stays at 0.4 . I was advised to add 1/4 strength nutes or ec of 0.8 at the start but 80ml into 70 litres is already more than a quarter recommended strength. So adding enough nutes to bring the ec to .8 would be a lot more than the recommended full dose.

Res temp about 21 deg and ph at 5.6 ish.

I mixed a jug of high concentrated nutes and placed the truncheon in it, the reading shot to 3.6 so it does work higher.


Any help would be appreciated.

Hey, im alil stoned, and i think i get what you are asking.

I dont use dutch pro, but i know when a company recommends a dosage it is used as a rough guide. So going offa their numbers thats 25ml per 10lts, that sounds about right.(hell most companys are going for the 2ml per lt mark. Haha)
Im using canna in a 10lt bucket and im adding 20ml a and b with extras and am getting an e.c of 1.1-1.2.

i re read your post and think i know what you mean now.. Are you worried your truncheon is off? If its a blue lab trun(i have one too) then its ment to auto calibrate etc. but you could always by some conductivity solution to check it is correct. Or as you mentioned, look at what they say you should get from a certain dose. So e.g. 100ml per 100lt is e.c 1.0(example). Mix it up and see if you get the right e.c.
sorry if im no help...take it easy..

Also, bluelab do state that you should allow the meter to acclimatise to the solution temp. And should be sturred to give accurate readings. Also i have found that after about a year of use the batteries start to go and this could also give you under readings. So maybe... Just spitballing now. If anything this will serve as a bump.. Take it easy..

Thanks for the reply Bunnyface. I just bought the truncheon a couple of weeks back so should be ok but I obviously don't know how long the batteries have been in it on the shelf so I will check that first.
I did do the stiring thing and also use the first dip to let it adjust to the res temp.
Dutch pro say 250-350 ml per 100lires of water should be around 1.8 ec, so I will take your good idea and make up a batch with the recommended and see if it comes out at 1.8 ec.

I am now thinking that they might mean to use 250-350 ml of each and not a total of the two combined. It would certainly increase the ec to a more realistic level.

Aye...bang on, also i love the bluelab truncheon, great bit of kit,
well best of luck and hope you get your dosages sorted. Take it easy.