I'm doing a soil grow in FFOF and feeding with Biocanna line of nutes.. I have a Hanna EC meter I'm using to measure runoff.. For the longest time during veg the runoff was >2000, I was told this was likely due to the plants not having grown through all the soil, so I was washing out fertilizers.. The last few waterings the PPM has been dropping a lot, it's at 950 now. My water is 20 PPM and my mixed solution is 100-120 PPM going in.. Should I be feeding them more, or more often? They are in 5 gallons of soil, I've been feeding them with 1.25 gallons of water twice weekly. They are currently 5 days into a 12/12 photoperiod and stand a little over 3 feet tall. I've been using recommended dosages of my nutes for the last 5+ waterings. Or is a low PPM no issue at all?
I dont understand, you said your run off is 950 and your nutes are at 100-200ppm going in? That doesnt make sense to me. I dont know much about soil so maybe the ferts in the soil bleed out in your run off???? BUT anyways, I think I am having the same problem as you. I am using a DWC set up and I just fed my ladies the other day at full strength lucas formula and it said my ppm was only like 400, when it should be at like 1100. And that was on 2 different digital testers as well. If your plants look good, I guess you should be happy if its on the lower side rather then it being on the higher side. Thats just how I see it.
What is full strength lucas formula? 0-5-10 or 0-8-16? Either way you need to get your meters checked. 0-5-10 in RO water should mix at about 850ppm. 0-8-16 mixes at about 1340 ppm (@.7 coversion). Check your calibration on your TDS meter. And if it has adjustable conversion scale then check that too.
Yah im sure that is the problem. Does anyone know if those cheapo tds meters even work correctly? I assume you dont have to calibrate a tds meter as often as a ph meter, but I have 2 cheap digi tds meters and they read complete different readings...
Hanna Instruments HI 98311 and HI 98312 EC / TDS / Temperature Tester - instrumart.com This is the meter I have. I've had it re-calibrated and tested again, but I'll need to wait until the next watering to test it on real runoff.. But it tested the calibration solution correctly the first time, so it was pry fairly accurate at ~950 PPM coming out ~120 PPM going in. The Bio Flores is 2-2-5, using at 15ml/Gallon (1:250).
Well in the absence of knowing wtf I'm doing with runoff, and that it's showing low instead of high, and the pH is good going in and coming out.. I'll just keep feeding recommended dosages and see how that goes.
Well I figured this problem out SORTA. It seems you cannot accurately measure EC with organic nutrients, like the BioCanna line I'm using. I'll just continue to use recommended dosages, as recommended =D
Sorry for not responding sooner. If you have the Hannah combo EC/TDS/TEMP meter (pen style), that is a great meter as far as I am concerned. Auto calibration and accurate to 1 pppm. If you are pouring in 120ppm water and getting 900ppm out, then you are flushing nutrients out of the soil. This means the level of nutrients in your soil would have to be pretty high. However, if you are not having serious issues i would just make sure the runoff ph is correct. every so often check runoff ppm and if it starts rising above 900ppm (with 120ppm going in) then that means the plant is using nutrients slower than you are feeding, so reduce the strength of your nutrients. If ppm in runoff start going down, then the plant is using them faster than you are feeding and you need to increase the strength of the nutes a little bit. \ Also, the Hannah meter has an adjustable conversion ratio, so make sure you know what is is set at (I believe it is adjustable from .4-1.0) I think most folks use .7 so it might be a good idea to make sure you set the meter to .7 conversion Good luck.