Hi chaps. I need some advise to see if I'm on the right track. I've a 1.2 x 1.2 x 2m tent using 250w envirolight for vegging. I'm on day 25 from first sprouting. Growing 4 "Bigfoot" seeds in a 30ltr res using dwc with two 4'' air stones. The pump seems large enough to handle the size of res. My temp ranges from 20oc at night and 25ish during day humidity ranges from 40-50% I've bought an inexpensive ec pen from amazon and the last reading was "378" with a flashing "x10" in the corner, I've read a thread on this showing my ec pen and the method to calculate is say, 378 x 10 x .5 = 1890. Is that low or high?. I keep my ph at 5.5 but it rises to about 6. The main reason I post is to have a look at my pics and let me know what yous think. My lower leaves look a little droopy and the edges are curled up and look a little dark, is this normal? And one leaf looks a little discoloured, is this nute burn?. Other than that I think all is looking well.
I don't think your math is right. I believe the pens are either .5 or .7, but you don't need to multiply by that factor since the pen automatically does it. That being said, 1378 (what I think your pen is telling you) is still way up there especially for young plants. I would drop that immediately. 350-500 sounds like a good range for the middle veg stage you're in - I don't know if it would shock the plants to go into such a diluted solution right away, maybe it's best to lower it gradually. It looks like you have good setup overall, so I wonder how your PPM got up so high in the first place. If you're following makers instructions, keep in mind they want you to use up the product and buy more. If you're not using 0 PPM water then you need to subtract that reading from your target PPM - ex. you have 100 PPM coming from your tap and you want 500 PPM in your solution then only add 400 PPM of your nutrients.
I'm really a noob with this ec meter. I understand it basically tells you how much nutes are in the res but I am finding it difficult reading it. I have took a couple if pics. 1 of the pen 2 the instructions 3 of the pen in tap water When I take a reading of nutes it's 378 multiplied by 10. Could you shine some light in it please
First thing for you to figure out is whether that pen is a .5 or a .7 - in the US they are usually .5 but I'm guessing you're in the UK. All the meters measure electrical conductivity (EC) and then multiply it by a factor to give us the total dissolved solids (TDS) reading, expressed in parts per million (PPM). So... EC 2000 * .7 = 1400 PPM EC 2000 * .5 = 1000 PPM So that 378 x 10 reading you're getting is just 1378 PPM, which coincidentally is very close to the example I used in .7 terms, which equals 1000 PPM in .5 terms. It's still pretty high and I would get it to about 1/2 of where it is. If you find that you have a .7 pen, then you can just multiply any of the PPM numbers you see around this forum by 1.4 to get your local equivalent. Conversely, you can multiply your readings by .714 to convert them to .5 scale. If you have a .5 pen, then forget all that and get your plants out of that soup ASAP. Find some purified water to start over with and give the girls a diluted feeding. Then read Bizie's excellent thread here. Either way I think you want to find a better source of water for your solution. Good luck, and report back please.
Thanks for the input. I've a lot to learn. So my instructions for the pen say that it is factory calibrated to 500us/cm I'm assuming that I use .5 in my calculations then? My nutes say 5-7ml per litre which was giving me 180ml each time I refilled my res which if the pen is correct is way too high. I'm not sure the problem is my tap water I just think it might boil down to too much nutes. Wen the lights come on ill change my water bringing the ec from 1300ish to say 1000? Or would a drop like that stun them?
No. I made it sound more complicated than it is. Your pen is doing the calculating and giving you a TDS/PPM number of 1378. What you need to know is if the pen is multiplying by .5 or .7. Look it up or contact the seller because it's hugely important. In the above example, 1400 PPM and 1000 PPM are equal, just measured on a different scale and both equal 2000EC. And while I agree your nutes are too high, don't disregard that PPM reading on your tap water. Most hydro users are starting with 0 PPM (or close to it, 50 or under) so that they know that everything in the PPM reading comes from the nutrient bottle. So if you're aiming for 1000 PPM, you need to add 750 PPM to your tap water. The smart thing for you to do would be to take a liter of water and experiment with that. Figure out how many milliliters it takes to get you to a desired PPM and then multiply it by 30.
Ok I'll try to contact seller to clarify although the pen has a "US" on the front. So lets say it is from the us. The most the pen is telling me when I dip it into nutes is 315x10 which obv is 3150 I'm adding the .5 calculation after. Surely following the directions of the nutes isn't giving me a final figure of 3510?
I have that same pen... I use house and garden aquaflakes and never need to go above 700ppm ever. Why convert to EC Just use it as ppms
Doesn't seem like you'd have a hard time figuring out what the deal is. Other than that, I'd say your plants are looking killer. Nice and short. Looks like your growing a head of lettuce. haha.
So private stalk, if the pen already measures in ppm and I was to keep my readings right I should never see the flashing x10 multiplier or else I would be sky high?
Personally I don't know about your nutes but anything over 1K ppm is super overkill in my opinion. I run mine around 300-500 in veg and 500-700 in flower and never had deficiencies or issues. I mean unless you had a monster that was taller than yourself it just won't require that high amount of nutrients ever.