Hydroponic system nutrient sensors help

I suggest that you do a google search for the: Hach DR/890 Colorimeter

It will give you an education into one way to test for chemicals in solution. It is widely used in industries (like mining and water quality) where people might want to test a solution for a mineral/element presence.

Hach also have an HQd meter which you should look at. (Sodium, Dissolved Oxygeb (DO), pH, Chloide, Fluoride, Nitarate, Ammonium.

Genrally when testing for elements in solution you will have to mix solutions and look for color changes.

In any case other people have done the work and provided an economical solution. I don't think that you require real-time monitoring.

Will those work for continuous testing? I'm looking for something that will monitor the levels of the minerals and nonmineral elements for an extended period of time.

But thanks for the start!

And I do require real-time monitoring as I'm looking for something that will give me results when I need them.

Incase you are unaware a hydroponic system is used to grow plants, so I require monitoring all times, as opposed to doing small tests frequently. I find that having a system that can monitor at real-time all the time (and yes of course I will need to re-callibrate the monitoring system)

I am quite aware of what hydroponic systems do and are.

What you are asking for does not likely exist except for specialized tests. If you look at the materials and read the data sets (in pdfs on the Hach site) for the reagant packs you will understand better what the issues are.

Part of my work as the science officer for a mineral exploration company is to hunt down this type of instrumentation and determine what is most likely to be useful in "field" operations and use by unskilled people. Unskilled in this particular area as they often have an MSc or PhD in geology -- though some have little education.

Now, if you want to invest large amounts of capital I can point you to companies that could no doubt design you a real time system -- but they would likely be based on the same techniques as in the hand-held hach and/or the DR 5000 photospectrometer from Hach. http://www.hach.com/dr-5000-uv-vis-spectrophotometer/product?id=7640447361

Some meters like pH meters and TDS meters probably can be implemented in real time -- but does the conductivity measure result from Copper, Silver, Aluminum or manganese? You tell me.

You need to go back to your basic chemistry and study of minerals to see why these tests work and why they are used.

I doubt very much that you need real time measurments of trace elements in any hydropnics systems.  Maybe Nitrogen based compounds and pH -- but why the others? What would be the benefit?

PS: I have designed heap leaching (Thisosulfate and Cyanide systems) and designed and built the electrowinning systems for plating out sliver, copper and gold -- so I do know a little bit about these systems. However, a little knowledge is a dangerous thing -- so I suggest you start digging for further information by starting with test systems that actually work -- and go from there. (So I am guessing less than you might think -- that plus studying agriulture for four years and computer engineering for four years -- so I have some relevant education to back up my opinion as well.) My point is not that I know a lot -- but that that I consider myself a rank beginner at this -- but apparently I know a bit more than you. Start digging! Basic R&D and investigaton should come before you specify the methodology.

I need something that can test the amount of the elements in the water, but all the time on a real-time basis. I'm trying to make a system that will monitor its self, and take care of its self. I'm wanting it to be able to read the amounts of the elements and add more if needed (the oxygen would require a pump and air rock)

Basically, I can't be around this for more then a few hours a day, and since I have limited time with a system that needs more monitoring the plants would die. This is why I need a system that can monitor its self and manage its self.

And I already know my basic chemistry, all metals conduct electricity which will effect the PH, but the PH needs to be monitored because the plants need it within a certain rage, as with the elements. If the element level gets too low, the system automatically gives the water more of that said element (again with oxygen, it will turn on the pump and pump air in), and same with the water flow, if the flow is too slow or too fast the system can adjust its self.

I've built a hydroponic system before, just it didn't work out because of my limited time; so this is why I'm here looking for help to create a system that will manage its self.

Now that I've explained that better, do you have a suggestion on how I can do this?

I think you will find that most "automated systems" measure only pH, TDS, and EC -- perhaps temperature and humidity. Much like I said. I suggested that you look at how the analysis systems work so that you can see what the issues are. Do that.

In the meantime -- if you have the bucks photospectrometers start at $9000  -- maybe you should consider one per element.

When you supply a budget figure maybe people can be of more assistance.

See here:

http://www.appliedspectrometry.com/pubpdfs/4-On-Line_Spectroscopic_Monitoring_of_Plant_Nutrients.pdf

and here:

http://peterphrastus.com/drupal/

And here:

http://www4.agr.gc.ca/abstract-resume/abstract-resume.htm?lang=eng&id=27755000000662

But surely you can use google too!

Best wishes.

This might be useful as well:

http://www.reeis.usda.gov/web/crisprojectpages/0213548-optical-fiber-sensor-for-plant-nutrients.html

Non Technical Summary

Nutrient concentrations in greenhouse crops have a direct effect on the yield and quality of flowering plants. Nutrients are often applied on a rule of thumb basis and the level of nutrients and salinity "in the bag" is controlled by leaching with the salinity level measured with a salinity sensor in the leachate water. However, specific nutrient measurement is expensive and often requires wet chemistry. Two different approaches have been used so far: Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) and Ion Selective Electrodes (ISE). The ICP method is very sensitive and selective however, it is also expensive: on the order of tens of thousands of dollars. The ISE method is portable and cost effective but suffers from interference from other species, is subjected to electromagnetic interference and requires constant maintenance. It is the purpose of this project to develop a unique, low cost multi point/multi parameter optical fiber sensor to monitor the primary nutrients (nitrate, phosphate and potassium ions), in hydroponics solution. This is a real time single strand optical fiber that has an active cladding sensitive to the targeted species.

So pretty much I can't automatically monitor anything except for PH?

Is there any way to monitor the amount of the water soluble fertilizer in the water?

As I said:

I think you will find that most "automated systems" measure only pH, TDS (Total Dissolved Solids), and EC (Electrical Conductivity).

Monitoring TDS of your water supply vs what is in the tanks should give you an indication of nutrients available -- i.e. a proxy.

You can also measure temperature -- air and fluid as well as humidity -- all important factors. From that data you can control the HVAC (Heating, ventilation, air Conditioning) -- more important than close momitoring of trace elements.

So whether you are growing "recreational crops" or tomatoes you can establish some controls. Most of the trace elements can be checked on a much longer time span -- whether it is once a week or a few times a day should not really matter. If you dump in too much iron -- you will get a pH shift (more acidic). So some things can act as proxies.

My suggestion is to get something like the Hach DR/890 and measure the elements on a regular basis -- but every few days -- or if you spot trouble.

As those research papers point out easy measurement of the trace elements may appear "soon". You can automate the constant measuring of the other elements -- but you will need mechanical systems to sample , flush and clean the measuring equipment. Not simple and not cheap!

You can also measure CO2 -- the more CO2 (to a point -- say 2% max) you will get beneifts for plant growth. See here : http://www.co2science.org/index.php

Useful articles there.

Oxygen sensing is expensive -- and likely not needed.

You could also measure and control hours of light and darkness. All useful in some ways.

If you have a million dollar budget -- contact me -- I'll help you spend it. If you have a $200 budget -- do what you can do most easily of what is most important -- pH and CO2 in my mind...

I will also point out that browsing through one of the Newark (newark.com) sites will help you track down sensors, Most sensors are analog (ADC) or TWI or SPI interface -- some of the humidity sensosr expect you to be able to pulse count -- measure freqncy of an oscillator.

Generally, most TWI sensors and SPI based sensors have a lot of intelleigence on board and will feed you back numbers as answers -- then it is up to you to translate. Many have "drivers" you can find on the internet and adapt to your use.

Go to the Newark site and look for Sensors or find the specialized sensor section. It might make more sense now.

Just one more note -- if you consider the question answered - mark it as answered as a courtesy to me and to everyone reading the thread.

If you have more questions start a new thread with specific questions or post them here as a follow-on to get the answers you need.

If you have followed up on the links I gave you your questions should be quite specific now.

I used to grow hydroponic vegetables. Really,  tomatoes, basil.  The easy way is to buy a commercial premix two

part fertilizer solution.  This is added to the circulating water in the hydroponic system until the solution is the right concentration. The electronics then only needs to monitor the dilution using a total disolved solids meter.  Small digital

handheld disolved solids TDS measurment "pens"  costs about $30-45. If you keep the water level constant the plants use the fertilizer and you add more as needed to maintain the disolved solids. Maybe one of the inexpensive pens could be modified to interface with your CPU, or maybe there are more expensive commercial TDSwith digital outputs   The commercial liquid two part mixes come comercially balanced and measured so you don't have too make all the measurements you describe. There are solutions balanced for bloom or vegetative growth.  If you worry about the other elements, just flush and

reapply the desired analysis fertilizer, unless you need to be a research lab wtih all the equipment and sensors. The premix fertilizer is cheap and a little lasts a long long time.