Dissolved Oxygen Meter Testing

[Dr. Penguin]

The DIY oxygenator is an amazing idea and sooooo simple (the best ideas always are...) I would love to get some test results with the DO meter. If the oxygenator indeed can supply enough oxygen for a moderate sized rez, I'm going to be chucking my air pumps!

 

[fireburner23]

According to several Koi and pond forums, the Baquacil oxidizer is the cheapest form of H2O2 out there, and most every town with a swimming pool supply store carries it. Those guys use it as an algicide and to elevate DO.
It can get tricky ordering strong oxidizers over the web. There are DOT shipping restrictions for the stuff, especially in quantity. My 1 gal bottle came enclosed in a plastic bag to prevent leaks. The bottle states you should not store it near flourescent bulbs.
I will warn those not used to playing with strong oxidizers, the stuff will burn you and eat holes in your clothes if not careful. And NEVER let the stuff get near any sort of hydrocarbon, unless you like visits from the fire department.

For the Baquacil oxidize, how many MLs per day would you recommend? This stuff look amazing. What a great idea!
Would you recommend this stuff over the regular 35% H2O2?

 

[luv2grow]

copy and pasted dont take it as gospel though:

25ml Oxy Plus @ 35% H2O2 to 10 litres water for sterilisation. Or 2.5ml per 1 litre

3.785 litres = 1 gallon
3.785 x 2.5ml = 9.46ml/gal or 10ml/gal Oxy Plus for sterilising.
Drug store H2O2 is 3% solution, Oxy plus is 35%. Will need 11.7 times more drug
store H2O2 to do the same as Oxy Plus 35%. 11.7 x 10ml = 117ml/gallon drug
store H2O2 to sterilise, OR 1/2 cup per gallon.
Below are the recommended concentrations for various mixes from each set of
instructions included with the 17.5% and 35% products. The parts per million of
H2O2 for each is also noted for comparison.
Will assume that 20 drops = one ml for the below.
H2O2 content 17.5% = 175ppm at 1ml per litre.
35% = 350ppm at 1ml per litre.
Increase oxygen content in hydro systems, for use 2-3 times a week = 17.5%, 5 ml
per 10L 88ppm
35%, 2.5 ml per 10L 88ppm
Increase oxygen content in hydro systems, for use on a daily basis = 17.5%, 5 ml
per 20L 44ppm
35%, 2.5ml per 10L 44ppm
Optimum H2O2 Levels for hydroponic systems. 30-50ppm for the 17.5% solution
30-100ppm for the 35% solution Note: 30-50ppm seems to be safe for hydro systems/tanks, and up to 100ppm may
be OK for a short period of time. Use your best judgement.


i just wanted to add i dont think its a good idea to be above 50ppm for any period of time, ive seen failed grow reports a number of years ago relating to this, the plants started to "burn" so id discount the high ppm addition..

 

[allouez]

What would you all recommend for anchoring a bare tube in the solution? I'd like to try without air stones, but the tubing might just float or flex its way to the water surface.

 

[luv2grow]

ok i found a research paper what basically said h2o2 added at 50ppm dropped back to normal levels (almost) in 2.5hours as the control sample level was.

i think sgt proved that in a test.



a time release like the oxydator wouldnt need to be entirely mathematically accurate, just release fast enough to keep the DO elevated while excess is given off as a gas.

oxydator A ~

height ~18cm

width ~9cm

aquarium size upto~ 400l

usage ~250ml oxydator solution 2-8 weeks @25c







if it did actually use 250ml in 14 days on time release with a 17.5% solution wed have a calculation like this,



250ml ~14 days= 17.86ml per 24 hours .74ml per hour=130ppm per litre~ by the resovoir size (100l) 1.3ppm. per hour



not a fucking lot.



double the h2o2 strength, double the catalyst 4x the ppm.. 5.2ppm extra sound better?



really it would be ok to run at 20ppm per hour the excess disappating in the 2.5hr timeframe, but levels remaining constant.



i rounded a few calcuations off and may have made mistakes and it is theory, in practise often harsh reality sets in..



by the way, if the "activator" is the catalyst that im seeing for sale, for just a few quid theres nothing to stop you buying that perhaps inserting a hypodermic through the h2o2 bottle lid, dropping the activator in the h2o2 bottle and placing it upside down in a homemade rest in the tank.



one piece of advice, if anyone tries it, do the calculation lol and a cold h2o2 ottle going into a warm resovoir will expand the contents and a shitload will squirt out..

 

[squarepush3r]

how about dis?

http://www.youtube.com/watch?v=j9jsHNt0ljs&feature=channel_video_title

 

[hippydan]

I'm so confused about the quest for more DO. Why isn't aeroponics used more often? Or foggers? Air should be the best medium?

 

[squarepush3r]

I'm so confused about the quest for more DO. Why isn't aeroponics used more often? Or foggers? Air should be the best medium?

aeroponics is too hard, and if your equipment goes south, all your plants die in a few hours

 

[Scrogerman]

I'm so confused about the quest for more DO. Why isn't aeroponics used more often? Or foggers? Air should be the best medium?

Hey mate,
Its well known Aero is king , but its the system with the smallest room for error/mistakes, not a forgiving way to grow if you get something wrong it goes down hill fast, real fast, if a timer fails or a pump or temps are out of whac, blockages etc etc its possibly curtains, theres more considerations with these systems, there harder to manage & master & its puts people off. Once mastered though, Aero is known to be one of the fastest most explosive ways to grow, if not 'The best.
I wanna try Aero systems for Cloning, FOG Cloners, EZ Aero. But atm Bubblecloning is so easy, with perfect results evertime for me, i get roots in 5-10 days everytime with very little maintainance.

 

[Scrogerman]

ok i found a research paper what basically said h2o2 added at 50ppm dropped back to normal levels (almost) in 2.5hours as the control sample level was.
i think sgt proved that in a test.a time release like the oxydator wouldnt need to be entirely mathematically accurate, just release fast enough to keep the DO elevated while excess is given off as a gas.

oxydator A ~

height ~18cm

width ~9cm

aquarium size upto~ 400l

usage ~250ml oxydator solution 2-8 weeks @25c
if it did actually use 250ml in 14 days on time release with a 17.5% solution wed have a calculation like this,
250ml ~14 days= 17.86ml per 24 hours .74ml per hour=130ppm per litre~ by the resovoir size (100l) 1.3ppm. per hour
not a fucking lot.
double the h2o2 strength, double the catalyst 4x the ppm.. 5.2ppm extra sound better?
really it would be ok to run at 20ppm per hour the excess disappating in the 2.5hr timeframe, but levels remaining constant.
i rounded a few calcuations off and may have made mistakes and it is theory, in practise often harsh reality sets in..
by the way, if the "activator" is the catalyst that im seeing for sale, for just a few quid theres nothing to stop you buying that perhaps inserting a hypodermic through the h2o2 bottle lid, dropping the activator in the h2o2 bottle and placing it upside down in a homemade rest in the tank.
one piece of advice, if anyone tries it, do the calculation lol and a cold h2o2 ottle going into a warm resovoir will expand the contents and a shitload will squirt out..

Hey man, your onto it. It should be pretty simple to run tests to work out how many Oxydators are needed to keep the DO ppm at a 'constant', amounts & sizes etc, your workings seem pretty sensible to me man but im not sure their right or not?. One pint of H2o2 at 35% gives off something like 130 pints of pure O2 iirc, so strength of H2o2 needs addding to the equasion too, but im not sure how that O2 equates to DO itself?
This is one of the reasons i mentioned the heating mat & H2o2 bubbler type trip. As the Oxydator gets warmer it releases more O2(at a faster rate), id want that O2(inlet tubing) to be cooled somehow so it wouldnt affect Res temps. I think we should keep playing with this idea. If Sarge is willing to put that meter to more good use, then im sure we can find a way to keep that DO up to 30-50ppms as a constant(id be happy with 20ppms tbh). Nice one man!

You said earlier that you'd seen study/papers? on High DO levels being reponsible for burning plants, can you post a link to this info man? The Lit i read stated Cannabis can handle 30-100ppms DO & use it, That info stuck in my mind as very reliable info from a trusted source. Nothing was mentioned about adverse effects, burning etc. Id be interested to hear more on effects of Constant saturated DO at 50ppms causing burning. Like i said before, i would be real happy just doubling my DO level to around 20ppms as a constant. Im pretty sure this can be achieved.

With the use of Oxydators, H2o2 & a DO meter, im pretty sure with a bit of adjusting/tinkering, a high usuable level of DO could be achieved as a constant.
My mind is flooded with different tests that could be done. Its that safe level/ppm of DO as a constant we need to find before O2 oxidising effects kick in.

Cheers!

 

[allouez]

I'm so confused about the quest for more DO. Why isn't aeroponics used more often? Or foggers? Air should be the best medium?

One thing I don't understand about aero is.. how you get the spray to properly hydrate a 5 gallon ball of roots? Do you have to use small plants?

 

[Sgt.Stedenko]

What would you all recommend for anchoring a bare tube in the solution? I'd like to try without air stones, but the tubing might just float or flex its way to the water surface.

For my testing I took two stainless steel nuts which had an ID greater than the OD of the tube and wrapped them in teflon tape to keep them in place.
Not recommened for stelath. The air line causes the nuts to bounce on the floor of the bucket and make a racket.
You can buy suction cups for air lines at the pet store which would work fine. I have 2 in my res and they dont budge.

 

[Sgt.Stedenko]

Round 2

Round 2

Many thanks to all who have provided input on this subject.

Yesterday, my Citral gal was due for a res change, so I decided it was a good time to do some more DO testing. I wanted to see if the results of round 1 were reproducible and add some new tests to the mix.

So the test went like this….
I filled my 4 gallon bucket with 3 gallons of tap which had sat in the bucket for 24 hours prior to testing. This time, I decided to start testing with some dilute lucas formula (0-4-8), which is where my Citral gal likes it, atm. This time, I used GH bloom and micro instead of the AN stuff. The nute concentration was brought up to approximately 1120uS and the pH was adjusted to 5.5. The solution was bubbled with a Topfin round airstone for approximately 2 hours prior to the start of testing. I bubbled the solution for this amount of time, so the pH would be stable and not rise over time from aeration.

Again, I recorded parameters for one hour, taking readings at time intervals t=0, t=10, t=20, t=30 and t=60. Following completion of testing for the Topfin ceramic airstone, I pulled the airstone from the tube and repeated the test using the bare tube submerged in the solution. Following the bare tube test, I added 27% H2O2 at the rate of 2ml/gallon and repeated the test recording parameters.

Once the hydrogen peroxide testing was complete, I decided to place my O2 saturated nute solution in my res with the Citral gal and see what happened to the DO levels over time. The res is a 16 liter Sterlite tote filled with about 2 gallons of solution. I use a Hydrofarm flexible air diffuser around the perimeter and a Topfin ceramic airstone on the middle of the res. Air is supplied by the craptastick Aqua Culture dual outlet air pump from WallyWorld.

Yesterday was day 28 of flower. Buds are set, and trich production and bud swell are in full gear.

As you can see, she is well developed and has an adequate root system which should tax the DO levels.

Root Soup anyone?

An interesting thing happened once I added the H2O2 supplemented solution to the res and placed the roots in solution. DO levels shot through the roof once the plant was placed in the res. Before placing the roots in the solution, DO levels were around 13 ppm (136% saturation) from the added H2O2. Once the roots hit the solution, DO saturation levels went over 200% and maxed out the meter for the first 10 minutes. I suspect the organic matter of the roots caused a release of O2 from the peroxide in solution, but that’s just a guess.

With roots now drawing O2 from the solution, I allowed the test to run for 120 minutes to look at O2 depletion rates over time. During this test, O2 levels dropped from over 18.9 ppm (200% saturation) to 9.86 ppm (104% saturation). How much of this depletion is from breakdown of the H2O2 and how much is from root demand, I don’t know.

I was about to pack up my shit when I decided to do one more test, this time cutting off the air to the nute solution and watching the near 100% saturated solution decline. I figured this test would demonstrate O2 demand from the root system. I also ran this test for 120 minutes, recording parameters along the way. At this point in the testing, my Citral gal was bitching about the declining DO, so I promised to take her out to a dinner and movie if she shut het trap. lol

The results of this round of testing indicate the bare tube still supplies more DO than the ceramic airstone, but just barely. Both were within 2/10 of one percent of maximum saturation. I don’t think a couple of hundreths of a part per million is much to get excited over, or reason to switch to a noiser air delivery system, at least in my setup.

The results of hydrogen peroxide testing again indicated 27% H2O2 provides a significant boost to DO levels, but the boost is short lived under load. With no oxygen demand, H2O2 increased DO levels almost 70% over full saturation and remained over 136% saturation (13 ppm) after 2 hours. Under an O2 demand, DO levels decreased from 17.74 ppm to 9.86 ppm in 2 hours. Without air being added, DO levels decreased from 9.85 ppm to 8.58 ppm in two hours.

Results of round 2 tests are attached.

 

[Sgt.Stedenko]

For the Baquacil oxidize, how many MLs per day would you recommend? This stuff look amazing. What a great idea!
Would you recommend this stuff over the regular 35% H2O2?

I've found the Baquacil to be the cheapest source of H2O2. 35% is way more expensive and the increase in % does not equal the increase in price.

I've applied it at 2ml/gallon in my tests and acheived near 20 ppm max. Personally, I think a chemical metering pump would be the best way to add peroxide to a res, but daily additions sure dont hurt, so long as you dont overdo it.
Makes for a squeaky clean res.

 

[Dr. Penguin]

Awesome work, I love the attention to detail. Its kind of strange to see such a high O2 release after the roots hit the water but like you said its probably the organic matter causing the reaction.

Have you gotten around to building an oxygenator yet by chance? I run a RDWC setup currently and I really don't appreciate the noise and complication of the air pumps. If I could set an oxygenator to throw pure oxygen bubbles down the input tube of my buckets (to give the bubbles time to dissolve) that would eliminate my need for the airpumps.

I've picked up some lead weights to use as a catalyst and am working on sourcing some Baquacil so I'm going to give it a shot regardless but some concrete results with a DO meter would allay my apprehensions.

 

[Sgt.Stedenko]

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.

 

[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?

 

[Carboy]

Rule of Thumb

Rule of Thumb

An axiom that won't lead you wrong is that the taller the column, the colder the water, the finer the bubbles the higher the DO.
Error comes in when the pump and the diffuser aren't properly sized. For example, 1L/min pump paired w/ a 1L diffuser will always produce more DO than a 1L pump running open ended, if the column height and water temps are equal. An undersized pump doesn't have the pressure to correctly drive a diffuser and it could very well be that an open end would give better results. An undersized diffuser would cause back pressure and again, open ended could give better readings. But everything being correct, the diffuser will always win over open end. It comes down to simple physics -- more air surface in contact w/ more water and that is what produces the most dissolved oxygen.
Great info on the H202. Could really dial in a sterile rez w/o danger of running too much and get an added O benefit as a bonus. Thanks for sharing what you are doing. CB

 

[thefatman]

aeroponics is too hard, and if your equipment goes south, all your plants die in a few hours

Too hard???

 

[thefatman]

The problems i see with Tubes is the output air & surface agitation is isolated to one spot, maybe a few square inches, whereas with airstones you agitate the whole surface area, if tubes are giving more DO, then imo the pump isnt big enough. see where im going there?
When i use my Kam-Air 70lpm compressor pump & 6 x 12" ceramic airstones, my 70litre tote is like a Jucuzzi. The surface agitaion looks like a bubbling white water rapid/river.

Hey fatman,
How can you say DO saturation is not its all cracked up to be? I think the oppisite, imo its one of the most overlooked & underestimated ways to boost nutrient uptake & growth. Its well known Canna can use much more DO than can be applied/achieved with the use of airpumps/waterfalls through surface agitation etc.
If Canna can use 30-100ppms of DO in a solution, & we can only max-out DO at around 9ppms at 68f, dont you think we as Hydro growers are missing out on something?.

I know when i add H2o2 to my Res, i see a real growth boost 'Visually', we know this boost comes from DO boosting nutrient uptake. Id like to see how far i can go with this & get upto the DO level Canna is known to be able to use.
More DO, More Nute Uptake, More growth, its a no-brainer to me man.

Im of the opinion, all we actually need to achieve maximum growth potential is a full balanced mineral nutrition & as much DO as can be achieved(upto 30-100ppms), & adding PK & or other mineral elements as required by growth phase/plants.
(providing we have optimal environment-of course!!!)
We dont need all these snake oil products the likes of AN are trying to ram down our necks, to achieve this.
Imo DO is the missing link & is Very overlooked. Anyone who uses H2o2 will surely attest to the growth boost they get from increasing DO levels.

btw, ive run NFT for years & never had root-rot once. The beauty of NFT is the system naturally creates a system of air-roots that sit above the nutrient film, so roots in NFT have constant access to air, different to DWC, which ive also ran for years.

Organics in Hydro or Hydro-Organic is relitively new imo, & it seems to me Manafacturers of Nutrients & Additives have for the last 20 years been pushing us all to use more & more organics in our hydro solutions. These Organic additives/nutes etc, are not nessasry in hydro & can give room to cause infections/pathogens to bloom. I see people having issues all the time. Full mineral nutrition & High DO to create a high aerobic environment is all thats needed for maximum growth. In future when i run hydro, im sticking to mineral based nutrition & H2o2, its all a hydro grower really needs for a trouble/pathogen free grow with max growth potential, because of elevated & optimal levels of DO. Im a believer!

G'Luck Guys!

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.