NEED HELP! Aerotube/NFT problems.

Nathan Renkas

New Member
I have been growing in a homemade aero/NFT 4" PVC pipe set up under x2 1000W for close to 5 years with very good success. Past cycles have yielded right around 2 pounds of high quality product. I use 2" net cups from start to finish with no media at all. My recent cycles, however, have been very sub par and I am concerned as to what is going wrong. My suspicions stemmed from low Mg/Ca levels. First of all I use RO water and my nute tank was running a little cool over the winter (60F), which I corrected with a tank heater up to about 75F. The pH was started at 5.2 and left to climb to 5.8, though I've learned that the lower pH can inhibit Mg uptake, thus I've started at 5.8 and allow it to climb to 6.4 before adjusting. Nutrient res also has an air stone to oxygenate. I'm using Botanicare Pro Bloom, Cal-Mag plus at 5mL/gal, Liquid Karma, Aquashield all at recommended rates on bottle. I also use 1/2tsp of unsulfured molasses per 10 gallons, superthrive at 1/4 tsp per 10 gals, as well as a high P-K from week 4 to flush. Grow tent is kept around 72-75F day and around 62-64F nights. Humidity has been around 30% during the day which I was wondering if that was too low and not allowing stomates to open for optimal metabolism. I also have CO2 enrichment which raises ppm to 1500-1800 for approximately 15 minutes each hour of the light cycle, then it falls back to normal 600ppm for the remaining 45 minutes of each hour.

As it stands, I have just started week 4 of flowering. Overall, the plants look yellow and hungry. Lower leaves are yellow and curling up probably from Mg deficiency. I've tried to lower EC (1.6-2.0) to remove excessive salt build-up, but that seemed to make problems worse. I am now running around 3.0 EC and it appears as if the tops are looking healthier, though the plants overall are very sub standard. Should I be running higher ECs with organic nutrients? Should I be running higher or lower than recommended ECs in a media-less system? I typically don't leach or flush during flowering until the last week. When I have flushed in the past it always leaves the plants looking hungry.

I know growing high quality product is an art form and I thought for a while I was getting pretty good at it. Now, however, I feel as though I've lost all confidence in my growing. I've never had any major problems like this in this system before, and everything I've tried thus far has not seemed to fix the issue. I have read so much conflicting information as to proper culture in a media-less grow. Some say very low EC is best, though I've also heard others go as high as 5-6EC for a similar system! I am very confused and desperate to correct these issues, if not for this cycle, then certainly for the next one. Any information regarding EC, pH, nutrient rates, temperature, etc. would be greatly appreciated. I will post pics tonight as the plants are in dark period now.

Thank you for your time!!
 

Sativied

Well-Known Member
I recommend against using any organic nutes in hydroponics (that's like 'driving' a boat) but in general the EC should be much lower, not higher. Measuring EC Is no longer as accurate when using organic nutes. While you meter may say 1EC, it won't be able to detect/measure everything accurately (or at all).

I"m currently in week6-7 of a test run (in flooded tubes) in which I stick at 480PPM (450-500), so about 1EC, from start to finish (except first week seedling and last week flowering). Previous runs it was roughly 600-900ppm (that's without additives). 2EC is quite high, some strains can handle it a peak vegging and/or peak flowering, but 3, 5, and 6 EC that more for growing tomatoes.

My guess based on your post is that you start feeding them too much PK too soon. Ditch the molasses (already silly in soil, in dwc it's nuts :)). Ditch the superthrive (doesn't do anything, has been debunked years ago in a large test) and only add to your nutesolution what your plants can actually use (hydro nutes with a NPK ratio that still includes some N).
 

Nathan Renkas

New Member
Thanks for the feedback, Sativied. A few questions regarding your remarks. First, I've heard many using Botanicare products in hydro or media-less grows with great success, myself included. What is the reason against using organic nutes in hydro other than an inaccurate EC reading? Secondly, why is Superthrive useless? I've used it from clone to flush as a B1 and auxin supplement. I have personally seen a difference using Superthrive vs nothing at least when rooting cuttings. Also, why ditch molasses? From what I understand, molasses provides complex sugars not only to the plants, but also beneficial organisms in the roots. Molasses also has available Iron, Magnesium, and Calcium in it. I am still adding some N through the Pure Blend Pro, I just supplement a higher P-K 'super bud blaster' during the last few weeks of flowering. What nutrients would you recommend for an aerotube/NFT set-up? Though I must admit, I have been using Botanicare products in this same application with great results in the past.
 

Sativied

Well-Known Member
Well, above all, don't change a working thing unless it's so be more efficient/effective (cheaper :)).

Organic nutrients require micro life to convert it into the same basic nutrient elements you can instead supply directly to the roots. Being able to measure the nutrient solution accurately (EC and PH) is one of the primary advantages of hydroponics, by using organic nutes you give up the control you gained in the first place. Although you seem to have it under control, 'living water' often leads to stinking unhealthy nutrient solution and requires additional microlife to keep it under control.If you want to grow organically (a fallacy by itself imo) grow on (living) soil.

I have personally seen a difference using Superthrive vs nothing at least when rooting cuttings.
No offense but that's exactly what most people say after they paid for it, and what has been debunked years ago in a large scale side by side where zero difference was noticed. Have you actually done a side-by-side and truly objectively noticed a difference? (that's rhetorical cause I know the answer)

Plenty of articles about it on the web, here's one that might convince you of the facts:
Miracle potions pop up from time to time shouting out the wonders that can be accomplished with just a few small drops of their B-1 enriched formula. Super-Thrive is the latest of these that I know of and one small whiff is enough to tell you that its main ingredient is indeed B-1. Someone always knows someone else that swears by this elixir of life and beginners are quick to try some of this magical concoction so that they too can have bigger, better, healthier bonsai, just like the pros.

The myth of B-1 spreads like the plague; it seems there is always someone crediting B-1 with reducing transplant shock, stimulating root development, increasing crop yields, and other such claims that sound too good to be true, and are.

I am sorry to say there is little truth in the claims of the advantages B-1 provides. Let us look at what the experts have to say.

Lauren Bonar Swezey in her article, “Does vitamin B1 help transplants take root?” stated that “…University of California research on vegetables failed to prove that B1 reduces transplant shock or stimulates root development. Researchers found “no discernible differences in color or vigor among treatments” when B1 and B1 plus iron, manganese, and zinc were used on peppers, pole beans, squash, sweet corn, tomatoes, and watermelons. Elsewhere, studies on chrysanthemums, citrus, and roses have reached similar conclusions.”

Sue McDavid, UCCE / El Dorado County Master Gardener, states that “Using vitamin B1 to prevent transplant shock has shown no benefit whatsoever after multiple experiments, both in a laboratory setting and in the field, on a variety of plant species. Using B1 may make the gardener feel good and certainly the manufacturer, but your plants will be totally indifferent to it.
src: http://ofbonsai.org/the-last-page/editorials/debunking-the-myths-of-bonsai

There have been plenty of discussion on molasses, I will refrain from starting one here but will repeat: "only add to your nutes solution what your plants can actually use" (plants create sugars, they don't eat them)

What nutrients would you recommend for an aerotube/NFT set-up?
Any of the known nutrient manufacturers will do. H&G Aqua, GHE (tri, duo or nova), Canna, etc. Either 1 part or in A+B components. Those are complete yet can easily be adjusted (with additives). I highly recommend doing a round with just the basic nutrients (e.g. A+B component) and than after transition change it to a NPK ratio more suitable for flowering (I.e. a little less N than during flowering).
 

Nathan Renkas

New Member
Thanks for the documentation regarding Superthrive. I am still iffy on your resistance to using molasses, as many hydro supplements actually contain molasses in them. I understand that plants make sugars, but I know that the sugar in molasses benefits the microbes in soil and solution by offering a food source as well as the micro and 2ndary macros molasses provides. Also, thanks for the nutrient suggestions and your time.
 

superstoner1

Well-Known Member
I hav run the full botanicare pro blend line for years in dwc and aero rails with fantastic results and never a problem, but I would never ever put molasses in my systems. That is asking for trouble, along with the heater.
 

Nathan Renkas

New Member
Here are some pics of the situation. This is almost 4 weeks complete into flowering. I have been using this system for close to five years, and this is the worst run I've had. Normally I have been getting around 2 lbs off 2 1000w, but I'll be lucky to pull a lb this cycle. I will ditch the molasses if you think its a problem, ss1. I will now use only 'sweet raw'. I just need to know what is going on here, why it happened, and how to fix it for next time. Is it salt damage? Is it magnesium deficiency? some kind of nutrient lock out? Im using reverse osmosis water, so should I be adding more cal-mag plus than recommended? How frequently should I change my nutrient res? Is there an alternative to clearex as a flushing amendment, or can I just use clear water for 24hr before changing out nutrients? I'm using a blue lab truncheon to get my EC's and they have been right around 2.6-3.2 for flowering. By the looks of your recipe in your 3 stages of flowering, ss1, you must have very low ECs during flowering. What should the EC be at with Botanicare nutes for veg and flowering? What should pH be kept at? I've decided to go all in and get the amendments and follow your recipe, ss1. Any other suggestions for nutrients? I also read that you use pond-zyme with barley, ss1. What is your recommended grams per gallon ratio for that. Any other beneficial microbials I should be using? Aquashield has beneficial microbes in it as well no? Sorry for all the questions. Thank you very much for all your time.
 

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superstoner1

Well-Known Member
Wow. First thing I would do is calibrate your ppm and pH meters then seriously cut the nutes. I rarely ever see over 1000-1100ppm on a .7 conversion meter in full flower and I'm pulling 36-44 ounces from 12 plants under a 1k every 3 weeks. If you have my recipe then go by the pH I have for each state of growth, and the plants will love it. I don't even do a flush anymore because I have no salt build up issues with proper nutes levels.
 

Nathan Renkas

New Member
Thanks for the feedback, ss1. I will do a 24 hr flush and then start with week 5 flwr recipe. Should I up cal-mag from 2 to 4 mL per gal because I'm using RO water? You are of superior assistance.
 

Nathan Renkas

New Member
So, The last cycle was cleared out pretty much a failed attempt, and now it's time for the next go-round. However, now there is an issue with dull, pale, slightly yellowing leaves during veg.
Here are the specs of the situation:
The first 2 pics show plants in their veg chamber aero rails under (x2) 250W HPS + 160W daylight fluorescents. I am using superstoner1's botanicare veg recipe and EC has been right around 0.8-1.0, pH 5.8-6.0. As you can see the plants are green and the leaves are shiny and upright. I moved them into their flowering tent a week ago and have been vegging to get up to size before flowing. The flowering tent is (x2) 1000W Hortilux Super HPS. The temp is around 72F and humidity is 40% day, 70% night. I kept the same nutrients for veg in the flowering tent. The problem is that after a week in the tent, the leaves have started to slightly curl under, while exhibiting a dull, dry surface as opposed to a lush shiny leaf. My guess is that the plants are getting light burn from moving under the 2 1000W HPS. Some plants seem to be paler than others. Are the leaves drying from low humidity? Is the ppm of the nutrients too low or too high? Do I need a higher rate of nutes for higher light intensity? Is there a slight Mg deficiency starting? I am currently using 3 mL/gal Cal-Mag Plus. Other than this the plants a pushing out nice new leads and look fairly healthy over all.
 

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superstoner1

Well-Known Member
looking great man you're doing a fantastic job make sure to pay attention to the pH ranges for each stage of the recipe
 

Red1966

Well-Known Member
Thanks for the documentation regarding Superthrive. I am still iffy on your resistance to using molasses, as many hydro supplements actually contain molasses in them. I understand that plants make sugars, but I know that the sugar in molasses benefits the microbes in soil and solution by offering a food source as well as the micro and 2ndary macros molasses provides. Also, thanks for the nutrient suggestions and your time.
I have used a system similar to yours. You really don't want anything growing in your reservoir in a aerotube system. It will clog your sprayers. Your sprayers should be on a cycle timer. 15-30 seconds on and 4-6 minutes off.Reservoir should be 68-70 degrees. I always used hydroton in my 2-3/4" cups. a small bag fills a lot 0f 2-3/4" cups, and it keeps light off the roots
 
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