Is there a (tomato) doctor in the house?

[txice]

Thanks for the reply Luches. I'm actually pretty clueless on the nutrient "stuff" so far. I've been trying to study up and learn what nutrients to use, when, and what to look for in the plants should there be a shortage and/or abundance of a specific nutrient. I have flash backs of having to cram for botony finals back in college :/...hehe.

I came into this basically not knowing a single thing about any of this stuff and have been trying to learn as I go...but I know I have a long way to go. When my friend and I visited a local hydroponic store to get materials for our first build, the guy at the store simply recommended we get the TechnaFlora "starter kit", which we did. I've simply been following the "recipie" that came with the data sheet in the starter kit. You can see the sheet I got by going here: Technaflora Plant Products - Recipe For Success and clicking on the US Imperial and/or English version of the file....and you can see exactly what I'm mixing up if it might help shed some light on anything.

I have decreased the off cycle for the pumps. All the systems are now running on a 15/15 on/off cycle during the light period. I'm experimenting with the cycle times during the dark period, but currently have it on a longer cycle. Not sure if this is wise or if there is a need to keep the feeding/watering quite as high during the dark cycle. Though I saw some improvement once moving the tomato plants to the new system and keeping the pump on continuously, a few of the leaves on the plants still seem very "droopy" and "saggy".

[GpsFrontier]

I'm experimenting with the cycle times during the dark period, but currently have it on a longer cycle. Not sure if this is wise or if there is a need to keep the feeding/watering quite as high during the dark cycle. Though I saw some improvement once moving the tomato plants to the new system and keeping the pump on continuously, a few of the leaves on the plants still seem very "droopy" and "saggy".

Generally plants don't need watering during the dark period (but shouldn't hurt) because they don't feed in the dark. Though if the roots are hanging in mid air they will dry out off and that would probably cause problems. I have not done an areoponic system yet, but I would want the roots to get some watering at night to keep them moist.

[txice]

I had always kept my smaller "cloner" system setup with a 15 minute cycle every 2 hours during the dark period and that seemed to do alright. The first night I moved some of my plants into the larger system, I didn't have a timer on the pumps yet and I simply turned them off for the entire dark period. The next morning when I checked on the plants one of my pepper plants had drooped all the way over and was laying on the lid of the system. About 15 minutes after having the pumps on again the plant was perked back up and standing tall again....so it obviously didn't like not getting any water at all (even though it was in a net cup filled with hydroton and no real root mass extending out of the pot yet). Yesterday I was able to get the pumps back on a timer running the 15/15 cycle during the light period and on a 15 minute cycle every 2 hours durin the dark cycle. Checking on the plants this morning they all seemed alright and (at least somewhat) happy. I think I'll stick with this cycle for a while and see how things go. Luches has got me really curious about the nutrient mix now so I'm going to try to keep researching that and hopefully I can get everyone to be really happy and growing. I do at least see continued development in the plants daily...so that's a little encouraging. Some of the plants (tomato especially) just don't seem to be as healthy as they could be, so I know I'm not "on the money" just yet.

[txice]

So a slow day at work = lots of internet research being done. Luches got me curious on the whole nutrient issue and extended research is certainly indicating that I'm probably running "too rich" so to speak. General consensus seems to be that plants early in the life cycle need lower ppm. Additionally the consensus seems to be that in a recirculating system ppm can be lower too due to the continuous feed of water/nutrient.

I'm thinking what I should do is stick with the Technaflora recipie for success, but simply cut back the overall dosage by X% while keeping the right proportions outlined in the recipie. Figuring out what X should be is the next trick. I've read where alot of people will start out with as little as a 1/4th strength mix and move up from there. That seems awfully low to me though (would reduce to somewhere to around 275ppm following the 1100ppm recipie). Think I should go that low? Or maybe just drop it by half and try out a solution of about 500-600ppm?

[GpsFrontier]

The first night I moved some of my plants into the larger system, I didn't have a timer on the pumps yet and I simply turned them off for the entire dark period. The next morning when I checked on the plants one of my pepper plants had drooped all the way over and was laying on the lid of the system. About 15 minutes after having the pumps on again the plant was perked back up and standing tall again....so it obviously didn't like not getting any water at all (even though it was in a net cup filled with hydroton and no real root mass extending out of the pot yet). Yesterday I was able to get the pumps back on a timer running the 15/15 cycle during the light period and on a 15 minute cycle every 2 hours during the dark cycle. Checking on the plants this morning they all seemed alright and (at least somewhat) happy. I think I'll stick with this cycle for a while and see how things go.

Plants that small tend to respond much faster to there environment. So even though they don't feed during the dark, it's wise to keep an eye on them and if you see wilting to increase the watering frequency. With my pepper plants, they got watered 30 on 30 off all day, and until about 1 hr after dark, then started 30 min before first light. During the night I watered them 3 times at 30 min ea with no wilting at night. This was during summer when the night time temps were around 95-100, and day time temps were got up to 115 at that time. I started with store bought plants though, so they were already about 6-8 inches tall and the relative tempuature was a little cooler. I also had them in upside down 2 litter bottles with a mix of grow rocks and coco chips. Coco chips hold moisture better than grow rocks.

(NOTE: You want the watering to continue into the dark (not twilit), and you want it to start at least 30 min before twilit.)

Right now I have 3 systems running. One gets watered twice during the night for 30 min each with no wilting. The other two are on the same timer and only get watered once at night from 11:30 pm to 1:00 am with no wilting. One of these systems is using 3 inch baskets with coco chips and the other one is 5 gallon buckets, also with coco chips as the growing medium. The temp is getting into the upper 40's at night right now, so heat is not an issue. I can probably cut back the watering for all 3 systems at night, but it's not hurting that I can see. With growing plants there are so many variables, the growing conditions, type of system, all the variables of plants growing environment, that observation is your best indicator.

Some of the plants (tomato especially) just don't seem to be as healthy as they could be, so I know I'm not "on the money" just yet.

I am learning how fickle tomato plants can be myself. Mine seem to have a virus or something that is stunting their growth as well as curling the leaves. Through some back and forth with the guys at General Hydroponics, as well as some extreme close up pictures I took of some insects that were later identified to be "Winged potato or pea Aphid's," we are narrowing it down. There are also other factors that are probably contributing, like nutrient temp, the variety of tomato plant itself, as well as cold weather. But it might be just easier to start over because they are still small enough to do that. Trial and error, process of elimination, and observation is the key to learning.

General consensus seems to be that plants early in the life cycle need lower ppm. Additionally the consensus seems to be that in a recirculating system ppm can be lower too due to the continuous feed of water/nutrient.

Yes, small plants wont need a full strength nutrient solution. Seedlings probably around 25%, 3-6 inches probably around 50%. But again everything is not exact because of all the variables, and trial and error and observation are the keys to learning. If you had two growing chambers you can do some testing and see what gives you the best results.

Think I should go that low? Or maybe just drop it by half and try out a solution of about 500-600ppm?

PPM is simply a measurement of nutrient strength, unfortunately a PPM meter can't tell you what elements are in the nutrients and their individual concentrations, just their total amount. For this reason I haven't even gotten a PPM meter. It will however tell you how fast the plant is taking up the nutrients that it is taking up. If you know the type of plants you are growing use more nitrogen this could be helpful, but as I can see only if you can just add back the nitrogen. With pre manufactured nutrients this is not an option.

Just adding more nutrients to the solution to bring it back up to the the desired PPM wont insure the nutrients are in the proper proportions. This is because plants will take up the nutrients they need and leave the rest. One plant might use up more nitrogen, then by adding more nutrients to the solution you would be adding all the elements to it, so the elements that the plant did not take up would be in a higher concentrations, and not in the proper proportions. Most beginners find it easier to just change the nutrient solution regularly, and then get over that initial learning curve first before trying to tackle nutrient composition.

[Luches]

Hi txice,

The good news first: plants not only seem- but actually are very adaptable to their environment and hence to the nutrient strength and composition you feed. In nature they need to adopt to different conditions as well. But that also makes it difficult to optimize hydroponic nutrition at a second level.

Advice for your particular case now: don't cut back the concentration radically, because on the other hand sudden and big changes is what plants take less well. As they (actually mostly) don't occur in nature.

The bad news: understanding formulas and nutrient composition is not easy in the beginning as there is very specific knowledge and understanding required, before it makes sense. Furthermore there are many misconceptions, actually due to the fact that people tend to simplify things for a better understanding. They also tend to do a lot of cherry picking that is linked to their own experiences and personal situation. All of it is quite understandable, but in many cases it's not exactly objective nor good enough for a general role.

The other problem is, that in most cases you can't give real good advice without rather extensive explanations. If you don't attach those, people won't understand the "why" part of it, and simply switch back to their own understanding of things, or go for the often primary information they grab from any website. If you overdo the explanation part, you scare people back in their misconceptions

And the real bad news: with any commercial nutrients, the possibilities of adaptation and balancing are always limited. You have to trust them, without actually knowing what you are doing.

My set of advices keeps the same:
1. for tomato use a tomato formula that is supposed to have low nitrogen and high potassium content, rather rich in magnesium and calcium.

2. Don't cut back nutrient strenght to 1/4 and not even to half. If you cut it back now, just cut back to about 75% of what you have now.

3. On a second level of understanding: the key element of any nutrient formula is not the total concentration, but the content (the amount) of single elements in the formula (as in NPK, Mg, Ca, S, etc.). It's the content of each element that makes the total of the nutrient strength, not the other way round. Using only the concentration as a variable (without knowing the composition) is indeed like tuning an unknown. The specs of any formula are in the composition- and if you change the concentration of your formula to a certain extend, (wether higher or lower) it obviously gets imbalanced and inadequate.

4. Hence diluting any formula (as in any commercial product) to a quarter of their initial strength, means screwing it all up and creating a perfect imbalance. If needed I can give an example of what actually happens to a typical nutrient formula, as soon as you leave the limits of it's initial concentration. In figures it makes a lot more sense.

5. Three main issues come with commercial products: A. The manufacturers need to conceive their product in a way they can keep instructions as simple as possible. Because that way they can sell to a wider range of customers. B. They don't want to reveal any of their professional secrets. C. Hence they won't teach you anything (or as little as possible) as they know that the best customer is an ignorant customer.

[txice]

Originally Posted by GpsFrontier

PPM is simply a measurement of nutrient strength, unfortunately a PPM meter can't tell you what elements are in the nutrients and their individual concentrations, just their total amount.

Yeah, I'm totally with you on this aspect. I'm not quite ready to dump the money into individual test kits/meters to be able to figure out the individual nutrient concentrations just yet....maybe later. So a TDS meter and a "ball park figure" will have to do for the time being...hehe.

Originally Posted by Luches

Don't cut back nutrient strenght to 1/4 and not even to half. If you cut it back now, just cut back to about 75% of what you have now.

Doh! Did full nutrient changes this evening and already dropped my mixutre by 1/4. I simply took the Technaflora recipie, multiplied the mix by the total number of gallons like I normally did, then divided that amount by 4. The ratio of each nutrient to each other is the same as what I'd used before, just not quite as much of each....though you said it doesn't necessarily work that way? Not the end of the world though because I can always add more nutrients.

This actually led me to another question (and probably a fairly stupid one). When I'm shooting for a certain ppm goal/target, should I exclude the ppm reading from the tap water? I'll expand on that a bit. When I use the TDS meter on my water straight out of the tap, it reads just a shade under 200ppm. So if I want to reach a ppm of say, 700 ppm for example...should I actually target a straight 700 ppm reading on the TDS meter (thinking this would be more like 500ppm of "nutrients" and 200 ppm from the tap water)...or would I actually want to take the reading up to 900ppm so it would be more like a true 700ppm of nutrients? Does that even make sense? I know it's not a straight forward answer because I don't actually know what compounds makes up that 200ppm in the tap water...but that aside, should I pretend like that 200 isn't really there and adjust my meter readings accordingly?

[GpsFrontier]

When I'm shooting for a certain ppm goal/target, should I exclude the ppm reading from the tap water?

That's not a stupid question but one I am not sure I can give the best advice for, especially scene I have never used one. The problem here is that you don't know what elements are in the fresh water that are giving you the reading anyway. Even if you did how would you compensate for it in your nutrients because it's a pre formulated mix? The best advice I have is to mix the nutrients to the manufactures directions (2 tsp per gallon etc.) then take a reading, and use that as your base reading.

[Luches]

PPM means parts per million and 1ppm = 1milligramm dissolved in 1 Liter. It's a unit that is actually used to determine elemental content in a nutrient solution in the first place.

For example 150 ppm of N (nitrogen).

TDS means total dissolved solids. Any of the commonly used instruments actually measure electric(al) conductivity and either display it millisimens/cm (EC) or converts it to what is supposed to be the solids of the elements in a solution in parts per million (ppm).

Obviously these instruments can only determine the total concentration and are not able to even make a difference between a nutrient solution and dissolved arsenic trioxide. Actually you can't even (directly) accurately measure the total ppm of your formula, because there are some other dissolved solids (molecules, ions) that aren't part of your actual formula. To put it in a simple way, they are provided by impurities or "contaminants" that are part of the chemical compounds which are used to manufacture nutrients.

Note that the final reading is always higher as the actual content in known nutrients. It depends on the composition, but the reading is always around 10-15% higher as it is supposed to be.

Watch out: with manufacturer's instruction, those 10-15% should actually be included. You do not have to add anything here.

About the ppm reading of your tap water and how to deal with it:
Basically you should add it, respectively put it on top of the recommended concentration. Why? Because if you subtract it from what you aim for, as a matter of facts - your actual nutrient concentration will be lower and not sufficient.

But a reading of 200 ppm is quite high and close to the limit to use without analyses. I'd rate tap water with 300 ppm as unsuitable to give you an idea.
But depending on the analyses, it's not so bad actually - because your tap water will most likely contain a lot of calcium, magnesium and iron in the best case scenario. And those elements are actually welcome. High content of chloride(s) on the other hand would not be really of any benefit but rather 'toxic'.

It's not a bad idea to have a look at the analyses of your tap water if available.

Conclusion: As long as you aim for the original concentration or lower, you should always put the ppm of the tap water on top. But in case you aim for a higher concentration, you actually should divide the tap water's ppm by 2. In your case you'd then only add 100 ppm to the ppm of the formula. Because seen from that end of the equation you will already have enough calcium, magnesium, iron or other trace elements as part of your nutrients. The content of macro elements will be "more" than sufficient as well in that case. Hence, no need to have all that "extra" from the tap water on top of it. Remark: I was using reverse logics here! The extra from the tap water will always be included, no matter how. You actually use 100 ppm less of your nutrient mix, when only considering half of the tap water's reading!