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Is zinc a problem?


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  #1  
Old 02-05-2010, 10:56 PM
le0n le0n is offline
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Default Is zinc a problem?

Hi, First post, I'm Leon a retired Australian living in Davao philippines. Am building a system for Tomatoes and hopefully a few Strawberries.

First I should say being where I am it's very difficult to just drop into Home Hardware or Bunnings to purchase what ever I want so it's an exercise in adapting what I can get to do the job.

Question, I know from being involved with raising Trout fingerlings that Zinc from Galvernised fittings used in the system would kill the baby Trout.

My first thoughts are it won't be a problem with Hydroponics however you never know. So is Zinc or using galvernised fitting in the system a problem?

Building a flood and drain system because it gets hot here and my thinking is the plants will get more oxygen during the drain cycle and the trick will be to let the roots get plenty of air without drying out.

Couple of pics of my system so far and it's a work in progress.

CIAO Leon..

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  #2  
Old 02-06-2010, 02:38 AM
GpsFrontier GpsFrontier is offline
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Quote:
Question, I know from being involved with raising Trout fingerlings that Zinc from Galvernised fittings used in the system would kill the baby Trout.
For Zinc, or any element to be ingested by the plant it needs to be water soluble. Like people, fish can ingest elements that are not water soluble, and may be a difference. I'm not an expert but I have not herd of any problems arising from galvanized or brass pluming in hydroponics.

"Zinc
(Z) is a catalyst and must be present in minute amounts for plant growth. A lack of zinc results in stunting, yellowing and curling of small leaves. An excess of zinc is uncommon but very toxic and causes wilting or death."

Personally I wouldn't hesitate to try it if that's all I had to work with.
Quote:
Building a flood and drain system because it gets hot here and my thinking is the plants will get more oxygen during the drain cycle and the trick will be to let the roots get plenty of air without drying out.
Yes, when the system drains it will suck down fresh air into the growing medium with every cycle. But as it sucks this air down into the root zone the roots are vulnerable to the air temp at every cycle also. The root zone should be kept between 68 and 72 degrees continuously. If the nutrient solution is 68 degrees, and it sucks in 100 degree air with every cycle the root zone will be warmer than the nutrient solution temp. More frequent, and shorter cycles would help this situation.

P.S. I would e-mail the nutrient manufacture and ask them if the metal would react with the nutrients in any negative way.
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Last edited by GpsFrontier; 02-06-2010 at 05:31 AM.
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  #3  
Old 02-06-2010, 09:03 AM
Luches Luches is offline
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Hi Leon,
Quote:
Originally Posted by le0n View Post
My first thoughts are it won't be a problem with Hydroponics however you never know. So is Zinc or using galvernised fitting in the system a problem?
Trout fingerlings are indeed very sensitive and just some ppm of te wrong stuff in the water might indeed kill them. Plants, even seedlings aren't that sensitive and are able to metabolize with ease what actually may kill trout fingerlings straight away.

If I am not mistaken those fittings are used for house water systems, aren't they? Well, if so - you would kill your plants when hosing your garden and soil... if there was that much zinc getting "dissolved"
Just be careful with any kind of acids (PH down), they could actually dissolve some more zinc as would be of any good.
Still, as I live in Thailand I am well aware of the problem that you never know what they actually use in their alloys and coatings. Their might be some contaminants in heavy metals or stuff. If I was in your case, I would try to find some PVC or any synthetic fittings for future projects, it's safer.

About the "danger" of high temps in root zone when ebbing due to "hot air"?
I don't agree with GPS at all. It doesn't work like that. Firstly the air isn't literary sucked in and it obviously cools down in wet media as well. And then there is the temperature of the media, which has a puffer. Secondly there is a difference between ideal nutrient temperatures and the root zone temperatures in media. If you have buckets like yours (I also have similar systems running) the temperature may raise anyway as the buckets are exposed to direct sunlight and at ambient outside temperatures at all time. Although the humidity in the media will cool them somewhat down (which is good). Yes, you need to care about the temperature in the buckets (root zone), but you will not be able to keep it between 68 and 72 anyway- that's simply impossible. In wet or dry soil (which is pretty similar to a bucket filled with media) there are also huge temperature fluctuations that exceed 70 or 80 by quite a bit. Roots can cope with- and adopt to that in the tropics.

In brief: I do not think that there is a problem of the sort with Ebb&Flood.
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Old 02-06-2010, 07:30 PM
le0n le0n is offline
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Thanks for the replys Guys,

Was only worried about the Zinc because who knows what is used in the really poor quality fittings here in the Philippines. The flower garden survives so it can't be too bad.

My project is a work in progress and not proceeding at a fast rate however I think I have enough bits etc to do some water testing later this week. This will be interesting as it will start to let me know the time cycles I can achieve. Have a 40 litre per minute pump which should pump at about 30 LPM with the head I'm using.

Plan to use one of those 24 hour timers with 48 on and 48 off settings. 15 minutes on time seems a bit too long for me to fill the buckets so I'm looking for an off delay timer relay to set the max time the pump runs for. Will have to find one that drops out while the signal is still inputting and resets when the input signal ceases.

Can get a truckload of Coconut husks so this is what I will be using maybe mixed with a a percentage of Rice Hulls.

Nutrient will be all I can get here and called Snap, developed by a University here for Lettace and Tomatoes so that should be OK.

Will keep you informed of my slow progress. To my mind it's not so important to succedd at the first attempt but to learn as we go alng.

CIAO Leon...
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  #5  
Old 02-06-2010, 10:33 PM
Luches Luches is offline
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Hi again Leon,

Sounds good to me, the nutrients developed at the university should do fine as they have figured it out and tested it for some time in local climate and conditions. It may even be better suited than some commercial product that is several times more expensive.

Same here for the timer, - but I guess your setup needs some 5-10 minutes to fill up anyway. You may reduce pump size to delay the filling time close to 15 mins. More important is to find out and adjust the ideal cycling time. You need to allow time to drain and "rest" but not wait until drying out.

Hint: do not use too much coco husk. It truly retains humidity and salts. I am in fact using a mix of mainly rice hulls and little coco, plus pea sized gravel with my tomato buckets. I'm not exceeding 15% of coco. With this mix my toms are doing fine and I have got a pretty stable PH.

PS: In case you need more fittings and can't find any at your place, we have got a manufacturer here in Thailand that produces PVC and PE fittings in 16, 20, 25 and 32 mm, sprinklers, hoses, sprayers, you name it they have it. They are of good quality have ISO 9001 standard and are very cheap. Contact me in case you want me to help out.
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Old 02-07-2010, 03:17 AM
GpsFrontier GpsFrontier is offline
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If you took a 2 liter bottle of soda, set it straight up, then took the cap off, it would be full of liquid. Then poke a hole in the bottom of it. As the liquid drains out the bottom, air would be sucked in through the top. Once all the liquid drained out of the bottle, it would then be filled with air. This is a fundamental law of physics, and no mater how much one might try, they cant change the laws of physics. I know of no place on earth that is immune to the laws of physics. Perhaps in the Bermuda triangle, I here strange things happen there. But where I live nobody or thing is immune to the laws of physics.

When the flood and drain system floods, the water pushes air out of the system and root zone as it floods. When it drains the water drops and the water is replaced by air. Unless your system and root zone is vacuum sealed, air will replace the water as it drops. Of coarse the growing medium and roots themselves will take up some of this volume, but not 100% of it. There is a simple way to tell how much. Just fill your growing chamber (where the root zone will be) with the growing medium of choice, then fill it with water to the desired level. Then let the water drain out of the bottom into a measuring cup (or container). The amount of water that drains out will be the volume of air that is sucked down into the root zone when the system is drained.

Also, I am aware that the air being sucked down into the root zone is cool down by the wet growing media. This is also another fundamental law of physics. But the fact is there is also another fundamental law of physics going on, the heat in the air doesn't just disappear like it was never there. It does go somewhere. The heat is exchanged with the water, and the growing medium itself. This fundamentally alters the temp in the root zone. If introducing a warm liquid to a cold liquid, the laws of physics state the cold liquid would get warmer. It would simply be imposable for a cold liquid to get colder by adding a hot liquid to it.

I gave an example earlier that the root zone temp would rise if hot air was introduced into it, I did not say how much. This is because I simply don't know, I have never done any testing to find out. I do know it will rise however, that's a fact. I don't know how much, it may not be much of a problem at all, there are many variables that will affect the heat exchange. If I wanted to know how much it's affected, I would get a digital thermometer with a probe (with proper temp range of coarse). Insert the probe into the growing medium between the middle and the outside edge of the container. Then simply watch the changes in temperature thought the cycle at the hottest parts of the day.

P.S. If I had a problem, I would try two things (after insulating the root zone, pips, tubing etc.). The first is to increase the frequency of the waterings (shortening the length of time not to water log the roots). The other is to try to cool the nutrient solution down below 68 degrees.
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Last edited by GpsFrontier; 02-07-2010 at 04:37 AM.
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Old 02-07-2010, 04:16 AM
GpsFrontier GpsFrontier is offline
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Quote:
15 minutes on time seems a bit too long for me to fill the buckets so I'm looking for an off delay timer relay to set the max time the pump runs for.
I could be missing something, but it seems to me that would not be any problem in a system designed with a sufficient overflow.
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Last edited by GpsFrontier; 02-07-2010 at 04:19 AM.
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Old 02-07-2010, 06:24 AM
Luches Luches is offline
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Actually these "bottle-based" E&F systems (also shown here at some threads or in the gallery) are build in order to having a quick evacuation during drain cycle. One could actually call it flushing. That's right those kinda suck literarily. I knew that - but wasn't talking about those.

Right, the laws of physics are always in vigor - apparently not understood properly by some ...

They are understood by observation and the relation between two or more observations, not on rhetoric - aren't they?
Instead of using rhetorical comparisons or anecdotical analogies, I strongly recommend to consider all variables and parameters there are in a given situation.

You are a sharp boy Gps, right - and good at physics as it seems? Well then have a closer look at Leon's setup. Do you know what a bottleneck is? Have a look at the diameter of the outlets in Leon's system and then at the size of the hose's diameter that comes next and is supposed to evacuate the collected amount of all outlets to the reservoir.

We have two bottlenecks here in a row. Firstly the small diameter of the outlets in the buckets that only allow a relatively slow evacuation from each bucket and the second bottleneck is the hose that collects the one from the outlets and limits the maximal flow again. The ebbing process will go too slow to have any "sucking effect". Technically speaking, 6 outlets have to be squeezed through a double 3/4 inch bottleneck. Because of the relatively low hight difference (which may vary and make some difference, though) enough pressure will not build up either. Yes, the airspace in the buckets will be filled up, you bet it will - but it will take quite a bit of time instead of happening quickly. How do I know that? Well, simply because I have build a system with a very similar diameter of In/outlet. A system with that outlet size takes an eternity to drain! Depending on the pump size (if you do not override it for the retourn) you even have a third bottleneck (that could be narrower than 3/4), that would slows down the draining process even more.

If the setup would use 1 inch outlets and a 2 inch collecting tube instead, well - then it would probably suck pretty much.

The other, actually more important point is that I do not see nor believe that there is any notable temperature change in the root zone of either setup (quick flush or slow drain). Naaaahhh, that's truly taking it too far with thermodynamical speculation without proof. I would only believe that if I would see any notable temperature changes when actually measuring the temperature inside the buckets (root zone if you like) with a actual field experiment- before, during and after drain.

Last edited by Luches; 02-07-2010 at 06:27 AM.
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Old 02-07-2010, 07:26 AM
GpsFrontier GpsFrontier is offline
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Quote:
Do you know what a bottleneck is?
Absolutely, but only slows down the inevitable, but still cant change it.
Quote:
Have a look at the diameter of the outlets in Leon's system and then at the size of the hose's diameter that comes next and is supposed to evacuate the collected amount of all outlets to the reservoir.
It doesn't mater, you still cant change the physics, you can slow it down by clogging the draining system. But one molecule at a time the physics are the same.
Quote:
We have two bottlenecks here in a row. Firstly the small diameter of the outlets in the buckets that only allow a relatively slow evacuation from each bucket and the second bottleneck is the hose that collects the one from the outlets and limits the maximal flow again.
You can choke it off as much as you want but that wont change the physics. whatever goes out the bottom, the same volume needs to replace the space that is evacuated. Granted that Air is a gas and is compressible and a liquid is not. But considering this is not under pressure I hardly think it would be measurable. In other words no mater how slow it happens the same principles apply.
Quote:
The ebbing process will go too slow to have any "sucking effect".
It dosen't mater how slow it happens, sucking is sucking. Think of a suction cup on a window. It sticks to the window because of the sucking action, but there is absolutely no air flow. Sucking action is a result of vacuum not air flow.
Quote:
Yes, the airspace in the buckets will be filled up, you bet it will - but it will take quite a bit of time instead of happening quickly.
I never said how long it would take, nor does it matter. The physics are the same.
Quote:
If the setup would use 1 inch outlets and a 2 inch collecting tube instead, well - then it would probably suck pretty much.
No, the physics are exactly the same, the difference is it would happen faster.
Quote:
The other, actually more important point is that I do not see nor believe that there is any notable temperature change in the root zone of either setup (quick flush or slow drain). Naaaahhh, that's truly taking it too far with thermodynamical speculation without proof.
Well unfortunately it's a fact, if adding a warm material to a cold one, the cold one will warm up. As I mentioned that there are many factors in that. How fast the heat transfers occurs is probably the biggest one. I did explain that I have not done any testing on those the effects. Although I did give directions on how to do the testing.
Quote:
I would only believe that if I would see any notable temperature changes when actually measuring the temperature inside the buckets (root zone if you like) with a actual field experiment- before, during and after drain.
What is notable? One tenth of a degree, one degree, ten degrees. To me any change that the thermostat can record is notable. Sure one degree wont be any problem at all, but it's certainly notable. Again I have explained how to check it if it's a concern. I would be interested in knowing the findings. I can't afford my own thermostat with the probe myself so I wont be able to do the testing anytime soon. If I see signs that the plants are wilting even though the pump is giving the roots enough water, I know there is a problem. Although it would be a problem well before I see those signs.
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Old 02-07-2010, 07:31 AM
le0n le0n is offline
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Put water to the system today. Boy the leaks. Not from the threaded joints but because I can't seem to get decent worm drive clamps here. Going back to Australia soon and will have a fair list of bits and pieces to get.

As for the timer, maybe I'm second guessing my self and one wont be needed however it's my gut feeling and I work a lot on these it's going to be better to have more flood and drain cycles than less. Will have to work my way through it. Hydraulics Engineer for 40 odd years.

Also happy with the flood and draining times so far. As you can see from the pics I'm using two 100 Litre plastic containers for my resivours and have a submersable pump in one and will route the overflow back to the second one use the full capacity of nutrient in both drums. Would be easy to fit a solinoid controlled valve to have to system drain back to the second drum if I feel there is need to do so.

Thanks for the interest in my system and it'a all thought provocking.

CIAO Leon...
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Old 02-07-2010, 07:41 AM
Luches Luches is offline
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Gps, you truly are a funny guy and one mad physicist of a kind
But then again, I am not geting into that pickle any longer. I am truly sorry, but you have to do without me for this-one.
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Old 02-07-2010, 08:00 AM
GpsFrontier GpsFrontier is offline
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Quote:
maybe I'm second guessing my self and one wont be needed however it's my gut feeling and I work a lot on these it's going to be better to have more flood and drain cycles than less. Will have to work my way through it.
Ya, observation is key. Adjusting to what you see is very important. As well as the key to learning. Going by the pictures, I don't know if you have a overflow system or not. Typically a flood and drain system does, and would solve your timer issues if I understand correctly.
Quote:
As you can see from the pics I'm using two 100 Litre plastic containers for my resivours and have a submersable pump in one and will route the overflow back to the second one use the full capacity of nutrient in both drums. Would be easy to fit a solinoid controlled valve to have to system drain back to the second drum if I feel there is need to do so.
I had a similar system setup using two 32 gallon trash cans for the reservoir. I used a siphon tube between the two containers (Just a 8 foot piece of garden hose) one end in each trash can. Water seeks its own level. So as long as the pump does not pump faster than the siphon can replace it, the water level will remain level in both containers. As long as the tube is at the bottom of each container, so no air bubbles will be able to stop the siphoning action. No electronic parts to fail, or run up electricity either. Just weight down both ends of the tube to be sure it is at the bottom.
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Old 02-09-2010, 08:34 AM
le0n le0n is offline
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There is a 1" plastic hose joining the two 100 litre drums as close to the bottom as I can place them. Should be big enough to keep the nutrient level in the two drums at near enough the same level during both the flooding and draining cycles.

Managed to find a few better quality worm drive clamps and now no leaks.

Will be maybe a month before there is any real attempt to grow any thing because of other commitments and lack of time.

Cheers Leon...
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Old 02-10-2010, 08:05 PM
le0n le0n is offline
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Have to say I'm not happy with my thread being Hijacked on some sort of personal vendetta.

I am outa here.

Good Luck with the forum.

Leon...
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Old 02-10-2010, 08:37 PM
Amigatec Amigatec is offline
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Please come back, this Luches dude has some seroius personnal problems.

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