Oxygen generator vs air stone? Concepts and DIY approaches.

Discussion in 'DWC/ Bubbleponics' started by Ganjineer, Nov 21, 2016.


    Ganjineer Member

    I got curious about the use of electrolytic oxygen generators from this thread discussing the O2 Grow dissolved oxygen emitters. However, there is little to no unbiased (non-shill) reviews about the product available.


    I'm interested in trying out this technology, but frankly the cost is far too high for me to justify that kind of spending without any proof of efficacy (aside from a few company funded studies) or analysis on the safety of byproducts that the system may produce. Additionally, I don't anticipate the cost will drop on the system anytime soon because the company has numerous patents preventing competitors from entering the market.

    I'm familiar enough with HHO generators to recognize that this design isn't particularly complicated from an engineering standpoint. Because of this, I thought I would share a DIY friendly design that should accomplish the same results as the O2 Grow system, while not breaking the bank.

    Design Principle
    The O2 Grow system operates by electrolysis of water. This process, in short, is the decomposition of water (H2O), by electrical current, into oxygen gas (O2) and hydrogen gas (H2). In practice, electrolysis is as simple as applying DC voltage across an anode (positive) and cathode (negative) submerged within the water 2H2O → 2H2↑(-cathode) + O2↑(+anode). The volume of gas produced by this process is 2:1 hydrogen to oxygen.


    Although the principal of electrolysis has been known about for over 200 years, there are some challenges when it comes to putting the principle into practice. The biggest challenge is corrosion of the electrodes. For example, steel, stainless steel, copper, and aluminum electrodes will all corrode relatively quickly. Hook up these metals to a 9v battery in a cup of water overnight; You'll come back to find some nasty stuff. Now imagine how much worse that would be in a salt-laden nutrient solution.

    In order to combat corrosion, proper selection of the anode and cathode materials is essential if you want to avoid regularly replacing them. The most common materials include titanium scaffolds in conjunction with mixed metal oxide (MMO) and platinum coatings. The anode is particularly susceptible to corrosion and so it is more important for it to have the MMO or platinum coating.

    Once corrosion is accounted for, the rest of the design is relatively simple. You properly space the anode and cathode and then apply a DC power source to them.

    My DIY Design

    1. MMO Titanium Mesh Anode - $15
    2. Titanium Mesh Cathode- $10
    3. Mean Well LPC-60-1400 (may be overkill) - $15
    4. Spacer for anode/cathode and various parts for enclosure- $5-10

    Total: ~$50

    I have access to a 3D printer, so I'm planning on printing an enclosure and spacer for the emitter. The space between the anode and cathode should be about 1-2 mm. You could use some nylon washers to get the distance right. Just make sure the anode and cathode are not in contact with each other.

    Here are some images of the cad model that I'm planning to print up...



    Upcoming Work
    At the moment this is just a concept. I've done some tests with the anode and cathode and have confirmed that the materials I specified are corrosion resistant. My primary goal right now is to do some testing with various DC voltages and current sources in order to optimize HHO generation rates while keeping heat generation down and minimizing the voltage.

    Whether or not this method will impact our yields is up for debate. I'm willing to give it a try and will update you with my findings. To be honest, I'm skeptical that HHO generators will prove to produce superior results to traditional air stones. However, I like to tinker and that in and of itself is worth giving it a shot.

    Obligatory Disclaimer
    Safety is paramount when working with electricity and water. These voltages and currents can potentially kill you. Use proper precautions.
    x.man, Forrestfirebuds and pinner420 like this.

    Ganjineer Member

    I experimented with various voltages and currents today.

    I made some crude spacers by wrapping electrical tape between the anode and cathode to get a gap of about 1.5mm.


    Sorry for the crotch shot...

    I then hooked the MMO coated titanium anode to the positive of my bench top DC power supply and hooked the plain titanium cathode up to the negative side and placed all of it in a dish of regular tap water.


    I then experimented with a few different drive currents. I found that at a current of 1.0 Amp the system required 25V.



    At 1 Amp the HHO generation rate is extremely high. In fact, it completely saturated a half gallon of water within about 30 seconds.


    I think that this should be more than enough to saturate 20-50 gallons with dissolved oxygen within a few hours. However, I do not have access to a dissolved oxygen meter, so I can't quantify this. For the 5 gallon setup that I plan to run, I will aim for drive currents of sub 1A. I will shoot for 0.5-0.7A. Based on this, Mean Well the LPC-35-1050 or LPC-35-700 would be a better choice of driver.

    As it stands right now, it looks like you can build an extremely low cost DIY version of the O2 Grow setup with the anodes/cathodes, alligator clips, a DC power source, and some electrical tape. I'll continue to work on making this a little more polished and less janky. I would really appreciate your feedback and suggestions!
    Last edited: Nov 22, 2016

    Ganjineer Member

    No bites? @MadNyeTheHydroGuy I saw that you were interested in experimenting with this. Let me know what you think!

    NapalmZen Well-Known Member

    wow. im saving this as i was considering talking to an engineering buddy to see if he could help me build this because an air pump for 6 5gal buckets is just too much noise for my apt. im actually getting some mats to put under my mylar tray to soften the vibrations from the buckets. the pump isnt that loud, but combined, the whole building shakes.

    Ganjineer, i thank you for showing me how easy and cheap this is to diy. ill try to share if i can build a good setup.

    Ganjineer Member

    Thank you! If you're just looking to get something set-up and running you can buy both the anode and cathode as a set from http://store.theamateurchemist.com/mmo-mesh-anode-titanium-mesh-cathode-2-by-6/ for $25. Then attach that to an old laptop power supply (>18V) and you'll be in business. I wouldn't leave it on for more than 30 min at a time because it will heat up the water. To combat this, you could put it on a short cycle timer to have it on for ~15 min every few hours.
    NapalmZen likes this.

    NapalmZen Well-Known Member

    So, I just talked to my buddy who is a chemist of sorts. he basically said that it will not only destroy nutes, it will turn the water toxic as it will cause multiple side reactions with each combination of compounds in the solution. on top of that, it can destroy your ph balance.

    I want to test it, but I don't want to lose any plants. I may make a control bucket next time around with one of my mystery seeds.
    WeedFreak78 and pinner420 like this.

    Ganjineer Member

    Interesting. What toxic compounds were of particular concern and did he say what the precursors were? The one that I was concerned with was the generation of chlorine from sodium chloride (2 NaCl + 2 H2O → Cl2 + H2 + 2 NaOH). However, the vast majority of nutrients don't contain sodium chloride. Please let me know!

    I think the fact that there has been a few white papers published showing significant increases in yield are enough to warrant giving this a shot http://www.o2grow.com/certified-tests.php . Granted, these studies were likely funded by the company, but university researchers by-and-large aren't willing to participate in studies where their academic integrity may be compromised.

    I think the first step is to establish if there are any adverse effects on the health of the plant. We should be able to establish this relatively quickly (a few weeks). From there, we can determine impact on yield and growth rates with controlled studies.

    tonygreen Well-Known Member

    I guess don't be smoking around the hydrogen ha, neat diy.
    WeedFreak78 and Ganjineer like this.

    NapalmZen Well-Known Member

    according to what i understand from the conversation, in a distilled h2o environment with no nutes, it would work. if you use anything else, there are trace amounts of 100's of compounds, and even i slight amount of something like lye would make a "nerve gas". it may or may not be toxic to us in trace amounts, but it will be poison to something like a small plant.

    on top of that, the compounds found in nutrients alone will be broken down in the same method as the splitting of the h2o. some of this will leave as a gas and some will recombine making a different compound. this can not only damage your ph, but can also damage your nute ballance.

    basically, it may not kill the plant outright, but can change the balance of everything drastically enough to change how/what your plants absorb as nutes and can change the final product.

    i will build one for my next grow and share results against a control plant. ill try to test thc as well.
    Heil Tweetler and Ganjineer like this.

    Ganjineer Member

    Good to know Napalm, let's get to the bottom of this!

    For an initial test I'm going to determine the effects of the electrolytic cell on pH and PPM in a standard, lucas formula, nutrient solution. My experimental control will be the standard solution with an air stone and pump. For the experimental condition I will use the same volume of solution, but with the electrolysis unit instead of the air stone. Every day for a week I will measure pH, PPM, and water temperature of the solutions. Obviously I'll post the results of the test here.

    I know this isn't perfect, but the test on pH and PPM will a least give us a sense of nutrient degradation as well as adverse synthesis of compounds.
    pinner420 and NapalmZen like this.

    Ganjineer Member

    Gives a whole new meaning to growing "fire" weed.
    tonygreen likes this.

    pinner420 Well-Known Member

    Currently using an awol o2 generator cycled 1/4.. loving it.. subbed..

    firsttimeARE Well-Known Member

    Whats the point?

    Does it grow better plants than a cheap stone and pump?
    Jimdamick likes this.

    NapalmZen Well-Known Member

    It's supposed to produce better DO. the increase in DO is supposed to have many benefits including from higher yield, more potency, and faster growth.

    firsttimeARE Well-Known Member

    And wouldnt the 2:1 generation of hydrogen to oxygen make the water more alkaline?
    Jimdamick likes this.

    NapalmZen Well-Known Member

    Yes. thus my above comments.

    NapalmZen Well-Known Member

    i have a theory as far as how to make this work.

    if it can be built to run continuously, the ph can then be metered and adjusted. this is because any system that runs an on/off system it will imbalance ph. testing and research beyond that would require a mass spectrometer as far as what it does to the nutes.

    MeGaKiLlErMaN Well-Known Member

    An HHO generator will work but its not very cost effective since the air pump uses like 35-50W and the HHO metal will corrode away faster than the pump will go bad... It will work but Im not sure why it would be used in this way... but an HHO CO2 generator would be a cool Idea.

    GanjaFarmerUK Member

    So, I am experimenting with this myself.
    I have built a device using stainless steel mesh (similar to the twinstar for aquariums) and can confirm that the breakdown of the cathode seriously impacts the colour of the water and leaves a film on the top of the water and as a result will not do.. (works great other than that!)
    I also discovered after having some contact with a rep from O2 grow and reading their patents that the spacing between the anode and cathode is extremely important as to not produce a chlorinated solution. Wondered why my testing solution smelt like my hot tub!
    The patent for o2 grow states that the ''critical distance'' is between 25 and 60 thousandths of an inch or 0.6-1.5mm (for those of us that have made it to the metric system). This is one of the most important things that needs to be addressed when looking to build a diy version.
    Further to my very brief read of their patents I discovered that as the OP has previously stated that at least the anode would have to be made of a far superior material as not to break down during the electrolysis process, iridium or rhodium coated titanium being the standard anode material of choice these days. Also extremely important..
    Unlike the OP's design I am not aware that o2 grow use 2 different types of materials for their anodes and cathodes, looks like they are both iridium coated titanium.
    Their rep rather unexpectedly enjoyed telling me that people that think they can make these devices for cheap don't know what they are talking about because the iridium that coats their device costs 900 dollars an ounce and is worth nearly as much as gold which is why their products are so expensive! (Don't know why he told me this but challenge accepted!)
    So, I went onto Alibaba and ordered myself up X2 iridium coated titanium expanded mesh plates.(at a total cost of 57 quid which included 30 quid delivery..)
    So expensive right?!
    And, that's where I am with my diy build so far.
    I'm posibly thinking that half the magic here is in the stabilising of the output frequency and also waveform because this is just simple science stuff guys, basic electrolysis, we all did this at school right?
    If anyone that has the O2 grow devices wants to kick in as to what magic there is in their boxes other than just a simply ebay chinese switching power supply then that would be a great help, I'm guessing just stabilising caps..
    I will keep everyone updated as to my progress as soon as the plates arrive and I've tested them for stability.
    I know this post is a bit old now but hopefully this bumps it and gets everyone talking again!
    Happy growing friends!
    Heil Tweetler likes this.
    J Henry

    J Henry Active Member

    I’ll bite! Interesting thread…

    Why do you really think you need more DO, do you know your DO is too low or just want more DO because more DO sounds good? There is probably no more than 1 out of 1,000 growers that ever have root rot and fungal infestations caused by low DO’s. At least that theme seems to be quiet consistent on forums, no fungi problems, never in 20 years of DWC pot grows.

    If the cost is too high for you up front, this supplemental oxygenating device will never be a viable option for you regardless of any reason you want it. No disrespect intended. Like having a knock-out looking woman for a wife, you lover her, but you cannot afford her ways and the relationship is doomed to failure, but the Judge says you will pay child support and alimony at the end of the road at the Court House. That’s another one of life’s torturous adventures that cost too much, was not affordable and we bought it anyway.

    But first, why do you think you need supplemental oxygen, have you ever tested, measured your DO to determine if you DO is low, unsafe to root balls and Bennies? 2nd if you have actually tested your DO and found that it is low and unsafe and you need a higher DO that is within the “safe range, well you may need supplemental oxygen? 3rd, just how much money are you prepared to pay/invest in supplemental oxygen equipment that insures a continuous supply of O2 24/7 for months during the grow season that will insure a continuous “safe DO range?” Just wondering why, that’s all.

    Electrolysis of water (O2Grow) does produce pure 100% O2, but the hidden, never spoken issue is… just how much 100% O2 gas does the O2Grow electrolysis oxygenator really produce when the electrolysis generator is in the “on cycle.” It produces no O2 in the “off cycle.” Is the cost and H2 explosion hazard worth the benefit you hope for?

    Actually there are far better supplemental oxygen technologies available than electrolysis of water if you’re interested in or need to increase your Dissolved Oxygen saturation greater than the limitations and restrictions of ambient air and or O2Grow technology limitations. O2 Grow does have some serious limitations other than producing 2 X as much Hydrogen gas, an explosive gas.

    Oxygen (elemental O2 gas) is not ambient air and unlike air, O2 gas is not free. Supplemental O2 gas technology will cost you a few bucks.
    Heil Tweetler and WeedFreak78 like this.

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