Dissolved Oxygen Meter Testing

[squarepush3r]

Too hard???

well, I believe the initial setup is hard for aero, if you get it up and running then it becomes fairly automated with a proper recycle timer. However, the issue of
1) clogged misters which is difficult to see or discover
2) failed timer
which can KO the system fairly quick, necessitates in my opinion, a hybrid system with a failsafe such as bottom 2" standing water at least.

Currently running coco coir, which is fairly easy to run and worry free, however is more nutrient and water intensive and may not product as high an output. However, coco allows for larger trees, which is a setback for aero (plant size). For a large plant size in aero, I would theorize that a root trellis/screen would be necessary to allow even mist distribution to the very large root mass as evenly as possible

 

[Scrogerman]

I say it is not all its cracked up to be because seldom is the issue too low of DO in the reservoir. The typical problems is finding ways to deliver adequate DO water to ALL THE ROOTS even when reservoir DO is at saturation levels or higher. Plants really do not have a high DO demand at low growing temps but DO needs do double for each 10 C rise above 76 degrees F. This happens while DO drops about 25% in the reservoir with each 10 C rise in solution temperature. The only easy way to achieve this high DO at up to 96 F is with air atomized or high pressure aero where roots are entirely suspended in air.

A good DO test is to measure the DO in the middle of root masses and compare it to the DO in the reservoir. ie the outer roots extract most of the DO before the water makes it to the center of the root masses in most systems.

New wave oxygen enrichment of air used in aqueous solutions is done not by generating oxygen but by using membranes to selectively remove the other gases from ambient air. Enrichment versus generation.

You make some good points, but are missing the ones i/we were trying to make. Its well known elevated levels of DO boosts Nute uptake. Ive seen this growth boost visually many many times using H2o2 over the years, & as H2o2 is pure water & pure O2, its pretty obvious whats going on here, The released DO makes the plants assimilate more nutes at a faster rate, is this saturation of DO boosting metabolism? i know they grow stronger, healthier, bigger, faster when they are in an elevated & saturated DO environment/solution. To me saying DO enhancement is overrated or whatever it was you refered to it as, was 'with respect' being ignorant to DO's growth boosting potential. I have no problem getting DO/Air into my root masses, just add more air/circulation myself, seems to do the trick, i do go OTT though man when it comes to air. Roots explode ime.

To me H2o2 & DO has not been studied/experimented with enough & is always overlooked imo. H2o2 is a cheap source of DO. Ive been down this additive/suppliment road for years man & now it comes back to basics for me. Full mineral based nutrition & H2o2 is all thats needed for max growth potential in Hydroponics. H2o2 has more going for it that the majority of Boost products on the market imo. Infact its getting ridiculious, need i mention AN's arsenal of BS.

New Wave O2 enrichment? never heard of that bro, tell me more please man?. I will still see H2o2 the way i do & i will still hold DO in as high regard as a Growth Boosting Additive/Enhancer. In a sterile Hydroponic system/environment, all thats needed is Full Mineral based nutrition (no organics), & High aerobic conditons. DO boosts nute uptake ime & it boosts it alot. I could go on but i think you can see where im at & what i mean. Cheers fatman!

I just wanted to say, people who run Bleach for their sterile/dead Res environment are missing out on something Big imo here. Bleach dont boost nute uptake & there are fewer benefits in comparision, H2o2 isnt much more expensive either. DO it peeps!

 

[Scrogerman]

Hey Dr. P,
No, I havent gotten around to building my DIY oxygenator.
I need to get a male thread x barb fitting to thread into my "reactor vessel" lid so I can capture all the O2. I plan on making mine to work outside the res with the O2 line being fed into the solution.
Just remember, with 27%, the reaction does get hot for a while, so plan accordingly. We dont need another Fukashima reactor meltdown.

Edit.
I did a little testing of the lead/peroxide reaction.
I took 2.74 grams of lead and placed it in 100ml of 27% H2O2.
The reaction is slow to begin with, not really getting interesting until about 7 minutes. Full hard core rolling boil reaction starts after about 30 minutes. At about 37 minutes, the reaction starts pulsing and getting a little scary. The highest temps I saw were 161F at 43 minutes. After that, the reaction slows and cools.
During my sixty minute test, O2 generation would rival an airstone from between T=20 to T=60. Before that, the reaction is similar to a fizzing soda poured over ice. During meltdown, it's like a boiling fizzy soda.
I killed the reaction after 60 minutes by adding water to the vessel.
I removed and dried the lead and the weight was now 2.62 grams. Visually, the lead had a gold patina in spots and a chalky apperance in others. I suspect when I cut the piece of lead, the unoxidized part reacted differently than the oxidized portion.
Needless to say, 0.12 grams of lead was consumed in the reaction. Whether it was dissolved in the peroxide solution or was liberated in the oxygen gas, I don't know.
We all know lead is toxic, so the use of lead at the catalyst should be questioned. If there's lead fume in the oxygen stream, I don't want that feeding my roots.
If someone with some chemisrty knowledge would chime in, I would love to hear what's going on in this reaction.

So you liked the H2o2 Bubbler idea then Sarge, cool, i can see it working a treat if its done right. Cooling that air may be an issue though, as i mentioned in earlier post. Cant wait to see ya knock that one up Sarge, great stuff man.

Im not down with the lead thing man, dont like the idea of using that as a catalyst myself, like you said its toxic & cant be doing anygood in there, certainly deserves consideration. There are plenty of other usuable cats out there surely.??

Your tests are getting better & more interesting N1, i think that DO saturation boost to 200% when you put the roots in, was the H2o2 doing its thing/reaction, speeding up its breaking down process & releasing more O2 rads, makes sense to me, after the little ive learned about this stuff.

One thing, im not sure about the nutes 'GH-M/B', does it contain any organics, looks like it does to me bro? If it does then its gonna break down & oxidise fast, as you'll know, so im pretty sure youve considered this, ive never used GH M/B myself, i just know any organic addy is a no-no using the H2o2.? thought id mention it bro, just incase it was overlooked

Onto the Oxydator tests bro, im very confidant DO levels can be regulated with the use of these things. Now i just need to find out about, how long it takes for DO to effect the mineral salt/elements & oxidise them, if they do at all? Anyone?

Anyway nice work Sarge k+, heres looking forward to the next lot of tests. Best of luck bro!

 

[TheBioMaster]

We have done DO testing since 2005 with strictly RDWC systems....@sarge -your testing and information posted is most excellent sarge and very much on par/target with some of our test results as well over the years. Its nice to see similar test results and comparisons that even show more proof that DO is very very important and often over looked in the hydro enviroment.

Its unforunatly also misunderstood...for example someone was saying that the DO was not being evenly distributed to the roots or something of that nature.....this is so not true and a clear misunderstanding of how DO saturation levels work and how proper DO testing is conducted. The saturation levels indicate just that.."saturation", meaning ALL the water molecules in your tank that is being tested. The variances start to come into play when you work the equations and add in "friction" or "head" and some other common factors that must be considered in calculating DO efficiency in RDWC systems.

The only way one part of your root system would not be getting the same DO levels as another part of it is if your solution does not come into contact with ALL of the roots which would indicate a circulation and water level problem....not a DO saturation level related problem.

Peace!

 

[Dr. Penguin]

Ok, after some research on the subject I think I have a good idea of whats going on. The general hydrogen peroxide decomposition reaction looks like this:

2(H2O2) --> O2 + 2(H2O)

Thats simple enough right? A true catalyst would appear above the arrow because it is regenerated and used indefinitely.

Whats happening when you use 27% H2O2 is the catalyst is getting so hot that in the presence of high concentrations of O2, the lead is forming lead oxide(II). IE, the strong H2O2 is oxidizing the lead instead of using it as a catalyst. I believe it would look like this:

H2O2 --> PbO + H2O

From my research on the subject, lead Oxide should only be produced with concentrations of H2O2 above 8%. I would be very interested in your results using a lower concentration of peroxide. My hypothesis is that you will find no change in the weight of the lead catalyst if you use say a 5% H2O2 solution.

Heat plays a major role in high concentration H2O2 reactions, the more heat produced increases the reaction rates which in turn produces more heat resulting in runaway reaction conditions which could cause vessel rupture. Never a good thing, which is another reason we should use lower H2O2 concentrations.

Now with that said, you should be able to see a precipitate of the lead oxide(II) freed from the lead weight on the bottom of the container as lead oxide(II) is insoluble in water at a neutral Ph.

Another thing to consider about using lead as a catalyst is the stabilizers in low concentration H2O2 will poison the catalyst rendering it less effective over time. But if we replace the catalyst semi regularly, we should be able to make an oxygenator that produces a steady stream of O2 for over a month.

This post got really long really fast. Sorry about my rambling.

 

[Sgt.Stedenko]

One thing, im not sure about the nutes 'GH-M/B', does it contain any organics, looks like it does to me bro? If it does then its gonna break down & oxidise fast, as you'll know, so im pretty sure youve considered this, ive never used GH M/B myself, i just know any organic addy is a no-no using the H2o2.? thought id mention it bro, just incase it was overlooked

Scroggerman,

What's organic in GH's 3 part flora line? Organic means containing carbon. The only carbon I see is in the calcium, potassium and magnesium carbonates (xCO3) used to derive the chemicals in the formula. Just because the nutes are derived from these mineral carbonates, does not mean there is carbon in the nutes. Hell, if you use tap water, there is organic material (carbonate ions) in the water. Are you saying H2O2 only works with RO or distilled water?

GH Flora Bloom:
FloraBloom 0 - 5 - 4
Guaranteed Analysis
Available Phosphate (P205) 5.0 %
Soluble Potash (K20) 4.0 %
Magnesium (Mg) 1.5 %
1.5% Water Soluble Magnesium (Mg)
Combined Sulfur (S) 1.0 %
Derived from: Magnesium Phosphate, Phosphoric Acid,
Potassium Phosphate, Potassium Carbonate, Potassium
Sulfate, Magnesium Carbonate and Magnesium Sulfate.

GH Flora Micro:
FloraMicro 5 - 0 - 1
Guaranteed Analysis
Total Nitrogen (N) 5.0 %
0.3% Ammoniacal Nitrogen
4.7% Nitrate Nitrogen
Soluble Potash (K2O) 1.0 %
Calcium (Ca) 5.0 %
Cobalt (Co) 0.0005 %
Soluble Iron (Fe) 0.1 %
0.1% Chelated Iron (Fe)
Manganese (Mn) 0.05 %
0.05% Chelated Manganese (Mn)
Molybdenum (Mo) 0.0008 %
Derived from: Ammonium Molybdate, Calcium Nitrate, Cobalt Nitrate,
Copper Nitrate, Potassium Nitrate, Zinc Nitrate, Potassium Borate,
Potassium Sulfate, Calcium Carbonate, Manganese EDTA, Iron EDDHA
and Iron DPTA.

Please tell us the exact chemical reaction between these so called "organic" nutes" and the peroxide.

I appreciate your input, but I've got to call a spade a spade when I see it.

To answer your question about the oxygenator, I think it's a gimmick. Even a DIY one at 1/10 the cost is a gimmick. From what I've seen, the decomposition of the peroxide using a catalyst slows to a crawl after a few hours. If you have to add more H2O2 to get the reaction going again, it's no different than adding H2O2 directly to your res. Why complicate things with some stupid reactor when you can get the same results with direct application of H2O2, minus the risk of a pressure rupture. KISS baby.

 

[Sgt.Stedenko]

Dr P nailed it on post 85.

FWIW, the 27% peroxide with lead becomes cloudy pretty quick and a yellow scum appears on the surface after full decomposition takes place. This is probably the lead oxide, which would account for the loss of mass of the lead.

I agree with Dr. P. No one should take this reaction lightly. Even a vented bottle with an airline leading to a bubbler may not accomodate the rapid generation of oxygen, and an ugly pressure rupture could occur.

Be safe out there kiddies.

 

[Carboy]

New wave oxygen enrichment of air used in aqueous solutions is done not by generating oxygen but by using membranes to selectively remove the other gases from ambient air. Enrichment versus generation.

I'm sure this is overkill for what we do but I'd like to learn more. Any links?

Another quick question for you, even tho it doesn't have anything to do w/ this discussion -- when you say "high pressure aero", what psi range are you referencing? thanks -------- CB

 

[luv2grow]

christ i just lost a lengthy post

http://www.oxydator.de/english/faqs/how_does_it_work_.html

better oxydator detail. i just ordered the A size, dunno where u are in the world but £37 on zooplus delivered 10% discount n free shipping 1st order. got extra catalyst/activator £3.79.

ill fill you in on what the catalyst actually is when i get it.

ive maybe just got time to test the rate in ml of h2o2 usage per 24 hours when it arrives to roughly guesstimate the o2 level.

it looks like its using a fairly non reactive catalyst to push the h202 out onto a more reactive second catalyst in the ceramic, it also says u can adjust the h202 and catalyst to increase output, (just what we want)
scrogerman heres the paper i took the DO dissapation rate from it shows sgt testing spot on.
theres a coupla graphs, fig 2 and 3 are interesting ones the h202 levels falling, the second is about the aerobic/anerobic bacteria.
http://www.aasv.org/shap/issues/v8n1/v8n1p5.html

 

[flat3ric]

1st of all thanks for this thread...extremely well done.

2nd, I'm pretty noob....but I was wondering if a DWC around 75% or so full of hydroton would retain more oxygen than straight DWC as a lot of the excess air would be trapped in and around the hydroton. Sort of like GH waterfarm except the hydroton extending all the way to the bottom of the bucket.

It seems like this would work great as long as there was enough air being supplied at the bottom?

Apologies for quoting myself...but can anyone give me some feedback on my idea?

Was thinking of filling 75% of a 3.5 or 5gal bucket with a neutral medium and good active aeration and I think the extra medium will help keep an oxygen saturated solution...?

 

[allouez]

I wonder if it would be possible to have something like... an automatic drip feed of H2O2. Lets say 3% strength. To keep the solution super-saturated.

 

[Scrogerman]

Scroggerman,

What's organic in GH's 3 part flora line? Organic means containing carbon. The only carbon I see is in the calcium, potassium and magnesium carbonates (xCO3) used to derive the chemicals in the formula. Just because the nutes are derived from these mineral carbonates, does not mean there is carbon in the nutes. Hell, if you use tap water, there is organic material (carbonate ions) in the water. Are you saying H2O2 only works with RO or distilled water?

GH Flora Bloom:
FloraBloom 0 - 5 - 4
Guaranteed Analysis
Available Phosphate (P205) 5.0 %
Soluble Potash (K20) 4.0 %
Magnesium (Mg) 1.5 %
1.5% Water Soluble Magnesium (Mg)
Combined Sulfur (S) 1.0 %
Derived from: Magnesium Phosphate, Phosphoric Acid,
Potassium Phosphate, Potassium Carbonate, Potassium
Sulfate, Magnesium Carbonate and Magnesium Sulfate.

GH Flora Micro:
FloraMicro 5 - 0 - 1
Guaranteed Analysis
Total Nitrogen (N) 5.0 %
0.3% Ammoniacal Nitrogen
4.7% Nitrate Nitrogen
Soluble Potash (K2O) 1.0 %
Calcium (Ca) 5.0 %
Cobalt (Co) 0.0005 %
Soluble Iron (Fe) 0.1 %
0.1% Chelated Iron (Fe)
Manganese (Mn) 0.05 %
0.05% Chelated Manganese (Mn)
Molybdenum (Mo) 0.0008 %
Derived from: Ammonium Molybdate, Calcium Nitrate, Cobalt Nitrate,
Copper Nitrate, Potassium Nitrate, Zinc Nitrate, Potassium Borate,
Potassium Sulfate, Calcium Carbonate, Manganese EDTA, Iron EDDHA
and Iron DPTA.

Please tell us the exact chemical reaction between these so called "organic" nutes" and the peroxide.

I appreciate your input, but I've got to call a spade a spade when I see it.

To answer your question about the oxygenator, I think it's a gimmick. Even a DIY one at 1/10 the cost is a gimmick. From what I've seen, the decomposition of the peroxide using a catalyst slows to a crawl after a few hours. If you have to add more H2O2 to get the reaction going again, it's no different than adding H2O2 directly to your res. Why complicate things with some stupid reactor when you can get the same results with direct application of H2O2, minus the risk of a pressure rupture. KISS baby.

Sorry Sarge, i should of been a little clearer mate, its just the way the nute line looks, i wasnt saying it defo contained any organic addy as ive never used the stuff. With its bright colours, just makes it look like it contains something Organic to me(which is Bad when using H2o2), esp the Grow which i know/realise your not using, what is the 3 part, illuminious Green, Pink, & Brown? something of that order. Theres alot of Hydro nute lines that contain organic addys & aint suitable for use with H2o2. I was just asking if GH line was possibly the same, i wasnt saying it definately had organic addys in it bro, i was asking?. No worrys, but always worth considering if using H2o2. Organics just get broken down & mess the composition of the solution up, so any line using organic addys at all is a no-go.

In response to your Oxydator/Reactor comments. I thought you liked the idea, & now its a gimmick? which one is it? lol?
Like i said i dont like using lead as a catalyst anyway & im pretty sure theres others ways to make the reaction, ye of little faith? All the H2o2 suppliers for Hydro, like Oxy+ state not to use further applications of h2o2 any less than every 24 hours, why is this if it dissipates after 2.5 hours or whatever it was? any ideas? Well the way i see it is, the only way to keep DO levels at a constant elevated level would be to add a reactor of sorts, keep a constant 20ppms would be nice, but im not even sure the plants could handle it 24/7 anyway. I had hopes for a test with Oxydators, but looks like your off the idea now. Oh well, have to get my own meter lol!

All the Best with your grows Sarge!
Cheers man!

 

[Dr. Penguin]

Lead is certainly not the only metal that will work as a catalyst. H2O2 will break down in a catalyzed reaction with any of the transition metals including Iron, Nickel, Copper, and Platinum.

Also, even more appealing safety-wise, the reaction can be catalyzed enzymaticaly with peroxidase. An enzyme found in high concentrations in yeast, liver, and potato.

I believe that a RDWC system of ~20-30 gallons could use two of these devices at 3% and a simple DIY CO2/O2 reactor (http://bobstropicalplants.com/Chuck/diy_reactor.htm) to provide all the DO the system requires.

If only we all had DO meters!

 

[Scrogerman]

I Certainly wont dissmiss the tec myself, any DO boost is gonna boost nute uptake to some degree, if we can regulate flow all the better. nice posts chaps!

 

[samba]

All right stoners,
Since no one in the last 5 years I've belonged here has taken the time or money to do this, I'm going to.
I just scored an Oakton Ion 6 Dissolved Oxygen meter with galvanic probe.
http://www.4oakton.com/proddetail.asp?parent=84&prod=333&seq=1&TotRec=6
I also just ordered some zero oxygen calibration solution and replacement electrolyte and membranes for the probe.
Total cost was $146 for the meter and supplies, shipped.
The meter and supplies ought to be in my hands in less than 2 weeks.
Once I get these, and get familiar with the meter, I plan on doing some testing of DO levels in a standard hydro solution using a couple types of airstones, bare tubes, waterfalls and maybe 3% and 35% H2O2. I'll try to do this as scientific as possible with controls where applicable. Probably some side by side buckets.
Maybe put to rest some of the bitchy attitudes around here that my setup is better than yours, etc, etc.
I dont use powerheads and I have no need for one, so dont ask.
I also am not going to buy every model or air pump or air stone, so dont ask.
Unless you want to mail me your equipment for testing, please dont ask me to spend additional funds for your amusement.
Thanks.

Edit.
See the links below for a shortcut to the tests.
A discussion of test #1 is found here: https://www.icmag.com/ic/showthread.php?p=4320743#post4320743
A discussion of test #2 is found here: https://www.icmag.com/ic/showthread.php?p=4337485#post4337485

I have been waiting for someone to make a tread like this for ages!!!
THANK YOU

Could you be interesting to trying out a Airlift pump to see what kind of DO you could get with it?
I played around with one I made today, and if surface tension braking is the way to get DO in to water, this could be it!

Its as simple as putting a smaller airtube in to a bigger tube, it will lift/pump the water, but a lot of mixing and splashing will happen. It might produce a lot of DO, or not...
Oh, and it has to stay vertical!!!

I made mine just by putting a 5mm airtube inside a 12mm clear watertube, and I can tell you there was a shit load of surface tension being broken, at least judging it visually...

Bad example made w/ Paint:

Red is airtube
Blue is just a tube that the water will be "pumped" up in

EXTERNAL LINKS:
http://www.youtube.com/watch?v=swMbm0KeV4M GO TO 6 MINUTES

http://en.wikipedia.org/wiki/Airlift_pump
http://www.youtube.com/watch?v=_kX0kY01FiE
http://www.youtube.com/watch?v=fpfjOs0IZfk

 

[Sgt.Stedenko]

Samba,
Interesting idea. I'll try it out.
Just to be clear, your're putting a bare tube down blowing out at the bottom of a larger tube placed in the res.
Would a 1/2" diameter piece of pvc pipe work for the outer tube?

Edit. Once I looked at your links, I know exactly what you're talking about. I've used that method several times to develop groundwater wells.

 

[Sam the Caveman]

I've got a little $25 ozone generator that was designed for purifying water. I use it now to kill the algae in my tap water. I'm sure it super saturates the water with excess O2, but how much compared to 35% h2o2, I don't know. However, the generator I have is just like a small air pump with a hose and an airstone. That would be much easier to cycle on and off rather than a doser pump with h2o2.

I bought my ozone pump on ebay and it was shipped from china. I has a dial count-down timer on the front of it, but I took it apart and wired around it to make it continuous so I could put it on an adjustable timer.

 

[habeeb]

don't have time to read this all, but its good to have a DO meter.. also don't see many with DO meters on here..

remember, I read you got this off ebay. you might want to buy a new probe, as not sure how the other one was stored.. which could give off readings, also found in the book, you need to calculate pressure in the meter to get accurate results..

also, as with any meter, weekly maintenance...


don't want to sound negative, it's just meters are only as accurate as the maintenance done on them..

 

[squarepush3r]

so, judging by the final test, it appears at an average developed root mass will absorb one half of one point of DO per hour. So, at this rate, things would be critical for the plant at approximately 2-3 ppm DO, or from 9-2=7 points x .5 per hour = 14 hours of no oxygenation.


As a requested test, I would be interested to see your final test run again (pumps and bubbles off) at times 1 hour, 2 hour, 3 hour, 4 hour, 5 hour, 6 hour, 7 hour, 8 hour, 9 hour, 10 hour

AND, once you are done at the 10 hour mark, then plug in your open air tube into the water supply, and track how fast the DO will return to higher levels (does it take 1 minute, or several hours to restore DO levels?)

I am interested in the time it takes to replenish DO depleted water to proper DO levels using standard air pump/circulation methods.

 

[Sgt.Stedenko]

Hey habeeb,

The probe is fine. There are no special requirements for storage of the probe according to the manual. The meter allows you to check the electrode properties for diagnostic purposes. The slope factor, % saturation offset setting, 100% saturation mV value and the 0% mV saturation value were all fine according to the Oakton tech I spoke with.

Once I received the meter, I reset the factory values and cleared the calibration data.
I've replaced the membrane on the electrode and refilled the electrolyte in the probe. I've also calibrated it before each session first setting the atm pressure to what wunderground.com says it is at the weather station closest to my house. It then gets calibrated to 100% satuartion in air, and then using a zero oxygen solution. I also adjust the salinity setting based on the concentration of the nutes using my EC meter.

About the only thing I haven't done to make sure readings are accurate is compare the readings to another DO meter.

Sam,

I like that idea better than H2O2. K+

Squarepush,

Nice idea. I'm just not willing to stress my gal for the sake of data.