hydro growing - PH & PPM/EC

topic posted Wed, June 17, 2009 - 7:56 AM by  D
what i like most about hydroponics is being able to have very precise control of your grow

One of the key things to watch in terms more advaced hydroponics is the relative changes in PPM or EC - the changes in the amount of nutrients in your hydroponic water - i've always used DWC (Deep Water Culture) which I think is best for small grows. But what is important is whether or not your plants are using nutrients or not and this is easily known by simply taking a reading and then either keeping track in your head or writing it down - I use yellow sticky pads which are all over the front of my grow cabinet. Computer savvy growers can easily chart this on a graph. You could look at just a graph of a grow and almost tell how the plants look without actually looking at them.

Basically, you want the nutrient level to go down every day - although, it may hold a day, but overall you want to see your PPM or EC going consistently dropping over time. This shows that the plants are using nutrient. When the nutrient solution stops going down and holds for two or three days then it is time to flush - my last flush came at day 11 when the EC went from 1.7 up to 1.9 - the wrong way. Usually with hydro you flush every ten days.

What happens is that over time the plants use nutrients but at uneven levels so that after ten days or so your EC or PPM reading may show a "good number" but the nutrient mix may have built up one nutrient that say the plants were not using so much and the nutrient mix might be weak in another nutrient that the plants have been using a lot of - and also, the nutrients can build up salts over time and this can cause a lock out - lock out is the most common problem and it causes the plants to show lack of nutrients since certain - or all - nutrients are not getting to the plants. Once lock out happens, adding more nutrient is useless - problem easily solved with a pure distilled water flush of the hydroponic system.

Another way this can be used at a somewhat more advanced level, is to determine the exact PH sweet spot for the plants you are growing - this can really make a difference - nail the PH sweet spot and then you can juice the hell out of your plants without burning them and get maximum growth. Of course, this works best if you have all the same strain in a given hydroponic set up. Also, when doing this, you have to be really really careful because if the PH gets off of the target "sweet spot", the heavily juiced plants will burn literally overnight - a two edged sword, this technique. Of course, one does not have to fly high with nutrient, simply finding the PH sweet spot will help them a lot and when using a more reasonable dose of nutrient level you don't have to worry about burning your plants up. I don't "fly high" any longer, haven't really found that it helps so much.

What you do is watch the PH closely and I used extremes here to make it easier - like I start with PH at 7 - really high PH for hydro - and watch the PPM and EC. By using extremes, I can zero in on the right PH easier. Say PPM is dropping but only a little so I change the PH to 6.5 and watch for a few days - maybe EC drops a little more showing me that I am going in the right direction so I change to a PH of 6 and then maybe 5.5, all the while watching those changes in nutrients closely. Eventually you hit on the exact PH that the particular strains needs for maximum absorption of nutrient and then maximum growth
posted by:
offline D
  • D
    offline 135

    Re: hydro growing - PH & PPM/EC

    Thu, June 18, 2009 - 8:09 AM
    Also, by simply tracking nutrient usage like this you can bring some kind of science to bare on techniques or products. I'm using House & Garden's BudXL (enzymes suppose to help the plants pull nutrients and sugers into the bud) and Shooting Star Bud enhancement products this grow. The Shooting star, with suger basically, is added later. The Buds are outrageously big and beautiful and they are using nutrients a steady, healthy pace. I'd have to say at this point that the BudXL appears to be doing its job?

    I use a product called Liquid Light by Dutch Masters which along with their product called, Penetrator as a foiler spray and is said to allow the leaf to absorb more light - a liquid way to increase your lighting. It works. I haven't used it in this grow because I knew I would be doing a long grow period and then I wanted to see what the BudXL did on its own. I'm getting virtually no upward growth just bulking of the buds. So now I'm hitting them with liquid light since I'm pretty sure the BudXL is doing its job and now we'll see what they can do together.

    But you could test any technique or product in this same manner - complement what your eyeballs tell you!
  • D
    offline 135

    Re: hydro growing - PH & PPM/EC

    Tue, September 8, 2009 - 9:10 AM
    my brother in law visited and he is a robotic engineer who runs a huge factory in Tx that makes liquid nitrogen - smart dude

    (kids - cut your hair, don't do drugs and go to school to be robotic engineers - that way, when the robots take over, they might let you live because you're useful to them. Kids you must look ahead in this world!)

    he showed me his live access via a laptop to the whole system and explained how it worked - not an easy task in itself to explain such a thing to me - and he can get me a master controller for maybe less than $2,000 grand when the one I was looking at was $6000 grand and he could set it all up for me if I fly him in - can't tell you what a relief that is. Funny thing is that he looks at many of the same parameters and I would like PH and C02 and the master controller can be both accessed and programed remotely from your laptop - everything perfectly controlled.

    I was explaining how I used EC readings and how when the EC stopped essentially going down and stabilized, it was time to flush the system and this usually corresponded to about ten days between flushes. He pointed out that the master controller could be programed to do exactly the same thing monitoring the same things I would and then taking whatever action I would according to the readings

    wow better living through MACHINES! How ironic

    Light movers imitating the natural movement of the sun, uv lights set to come on twice a day for 30 minutes during the afternoon, precise control of CO2, temp, humidity, airflow, nutrients - sorry outdoor hippies this does give me a woody although my outdoor girl is doing great and I'm thinking of offering a soil line if there is significant interest from customers? Definately wouldn't do it for myself though. I like the control you get with indoor technology

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