Yeah, n1 sarge! nice nice piece of kit bro! looking forward to these tests. H2o2 all the way!
Dissolved Oxygen Meter Testing
- Thread starter Sgt.Stedenko
- Start date
G
greenmatter
tagged
This is the point bro, you could do as much manual aeration via circulating/waterfall/bubbling etc as you like but you cannot reach more than 9ppm(approx) at 68f in normal atmosphere, which is about the cut-off temp for happy plants/roots. Canna can use 30-100ppms DO. H2o2(DO) stays in solution for much longer than seconds bro. H2o2's use is a simple method of achieveing that optimal DO level to help max-out nute uptake. Couldnt be easier.
Im seriously considering going back to using a simple mineral based nute line & h2o2, with a bit of PK, biggest fastest yields ive ever had, & the visual growth boost i see using h2o2 is undeniable.
One negative is not being able to use organics or bene's etc, but in Hydro do we really need this shit, no we dont, what do we need bacteria or organics for. Boost DO, increase nute uptake, but it cant be done by simply agitating/circulating water in normal atmosphere/pressure(not to the 30-100ppms DO we're after anyway).
G'Luck man!
T
thefatman
fatman7574 the seller of the Oakton meter..the fatman....Hum? Enjoy the meter Sarge.
thinkin
Member
bravo good score!
sweet research!
like the simple 3 senario test examples.
Your research applies directly to my app. THANKS!
Always curious how much air should be pumped per quantity of water for max DO.
I over DO it.
lol (pune intended)
running a similar two SWCs (~1.5 gallons per 2 plants) with 100 whisper and 60 whisper.
Oh yeah. Also add in 2 ml (per rez) of 12.5% h2o2 per day.
sweet research!
like the simple 3 senario test examples.
Your research applies directly to my app. THANKS!
Always curious how much air should be pumped per quantity of water for max DO.
I over DO it.
lol (pune intended)
running a similar two SWCs (~1.5 gallons per 2 plants) with 100 whisper and 60 whisper.
Oh yeah. Also add in 2 ml (per rez) of 12.5% h2o2 per day.
Last edited:
Hey Fatman,
Welcome to IC Mag.
Welcome to IC Mag.
Dissolved Oxygen
Dissolved Oxygen (DO) refers to the volume of oxygen that is contained in water.
The amount of DO that can be held by water depends on 3 factors: water temperature, salinity, and atmospheric pressure.
1. Amount of DO increases with decreasing temperature (colder water holds more oxygen);
2. Amount of DO increases with decreasing salinity (freshwater holds more oxygen than saltwater does). Similarly, stronger nutrient solutions hold less DO than pure water;
3. Amount of DO decreases with decreasing atmospheric pressure (amount of DO absorbed in water decreases as altitude increases).
Below is a table illustrating maximum DO concentrations in water at varying temperatures.
Temperature (°C)/DO (ppm)
15 /10.07
16 /9.85
17 /9.65
18 /9.45
19 /9.26
20 /9.07
21 /8.90
22 /8.72
23 /8.56
24 /8.40
25 /8.24
Measurement Units
One measure of DO in water is parts per million (ppm) which is the number of oxygen molecules (O2) per million total molecules in a sample. Calculating the % Saturation is another way to analyze DO levels. % Saturation is the measured DO level divided by the greatest amount of oxygen that the water could hold under various temperature and atmospheric pressure conditions multiplied by 100.
What Is Being Measured?
DO probes respond to the partial pressure of oxygen in liquid or gas being measured – they measure the “pressure” of oxygen rather than concentration. All of the oxygen entering the probe is consumed at the cathode where it is electrochemically reduced to hydroxyl ions producing an electrical current within the probe:
Since all oxygen entering the probe is chemically consumed, the partial pressure of oxygen in the electrolyte is zero. Therefore, a partial pressure gradient exists across the membrane and the rate at which oxygen enters the probe is a function of the partial pressure of oxygen in the gas or in liquid being measured.
When a probe is placed in air saturated water, the current it produces will not be affected by the temperature or salinity of the water. The DO concentration in the water, however, will vary with temperature and salinity. Because it is convenient to report DO concentration in mg/L or ppm, it is necessary to adjust for temperature and salinity of the water to get correct readings in these units. If DO were to be reported in terms of partial pressure or % Saturation, then temperature and/or salinity compensation for oxygen solubility would not be necessary. Most probes are temperature compensated – i.e. they convert the “partial pressure measurement” to mg/L of DO at whatever temperature the water happens to be at for a given salinity and barometric pressure.
Test Results
So let’s see what happens in a standard hydroponic solution. For your consideration, I started with standard tap water. Three gallons of tap were placed in a 4 gallon bucket and allowed to stand for 48 hours. The parameters of the water after 48 hours were the following:
pH: 7.52 units
Conductivity: 376 uS
Temperature: 18.0 °C
DO: 9.43 ppm
Alkalinity: 80 ppm
Total Hardness: 220 ppm
Calcium Hardness: 110 ppm
Conductivity, pH, DO and temperature measurements were made using my Oakton meter collection. All the meters were calibrated prior to use. Alkalinity, and calcium hardness tests were performed with a Taylor titration kit, and total hardness was performed using a pool and spa test strip. For the DO meter, atmospheric pressure was set at 760mm Hg, and salinity was adjusted throughout the testing to compensate for the addition of nutrients. Salinity reading were set at 0.1 ppt (parts per thousand) for plain tap, 0.7 ppt for dilute lucas, and 1.2 ppt for full strength lucas. I assumed a conversion factor of 0.7 for calculating the salinity measurements from the EC readings.
For the first round of testing I started with a standard WalMart Aqua Culture dual outlet aquarium air pump (for 20-60 gallon aquariums). The pump is max rated at 1200 cc/minute. I decided to test the pump using a Topfin 4” diameter airstone (blue ceramic standard run of the mill stuff), a bare tube, and a Hydrofarm 3’ flexible air diffuser. All tests were run for 60 minutes, and parameters were recorded at 0, 10, 20, 30, and 60 minute marks. I tried to maintain a constant temperature of 18°C for the entire duration of testing using a frozen bottle of water to keep temps stable.
Beginning with the straight tap, I added the Topfin ceramic airstone and recorded parameters for 60 minutes. After 60 minutes, I added a dilute Lucas formula (0-4-8) using AN Micro and Bloom and pH adjusted to 5.66. The test was again run for 60 minutes and parameters were recorded. After this test, I bumped the nutrient solution to full strength Lucas (0-8-16) and continued the test, all the time using the Topfin airstone. The purpose of this test was to determine the effects of nutrient concentration (salinity) on DO concentrations.
Following completion of the full strength test, the Topfin ceramic airstone was removed, and a bare 1/8” diameter tube was placed on the bottom of the bucket. Again, parameters were recorded until the test was complete. Following completion of this test, the Hydrofarm flexible diffuser was added to the airline and the run for another 60 minutes. The final test involved adding 27% H2O2 at a ratio of 2ml/gallon to the full strength Lucas solution. Testing was conducted for 60 minutes and parameters were recorded.
The H2O2 I used was 27% Baquacil pool and spa oxidizer. $20/gallon. The MSDS sheet indicates it’s 27% H2O2 and 73% distilled water. There don’t seem to be stabilizers in the stuff from what I’ve found, but they may be there in minute concentrations and omitted on the MSDS.
The results of testing are interesting, but not conclusive. Since this was done on a solution with no oxygen demand (i.e. no roots absorbing oxygen), It’s difficult to determine the effects of oxygen demand at this time.
At this point, you’re probably saying just shut the fuck up and tell us the results.
Without further adieu, the winner of test #1 was the bare tube, followed by the Topfin airstone and the flexible diffuser. A side note is the bare tube was the loudest while the Hydrofarm difusser was the quietest. Adding H2O2 to the solution does increase DO to supersaturation levels (max 122%) at the 2ml/gallon application rate. I’m currently testing the H2O2 in my reservoir with a 3 week old flowering plant to test the rate of oxygen consumption. It looks like the supersaturation levels diminish to standard saturation levels within about 2-3 hours of application. It appears H2O2 has little to no effect on pH or conductivity, so adjustments should not be necessary once applied.
Attached is a table showing the results of Round 1 testing.
Lemme know what you think.
Dissolved Oxygen (DO) refers to the volume of oxygen that is contained in water.
The amount of DO that can be held by water depends on 3 factors: water temperature, salinity, and atmospheric pressure.
1. Amount of DO increases with decreasing temperature (colder water holds more oxygen);
2. Amount of DO increases with decreasing salinity (freshwater holds more oxygen than saltwater does). Similarly, stronger nutrient solutions hold less DO than pure water;
3. Amount of DO decreases with decreasing atmospheric pressure (amount of DO absorbed in water decreases as altitude increases).
Below is a table illustrating maximum DO concentrations in water at varying temperatures.
Temperature (°C)/DO (ppm)
15 /10.07
16 /9.85
17 /9.65
18 /9.45
19 /9.26
20 /9.07
21 /8.90
22 /8.72
23 /8.56
24 /8.40
25 /8.24
Measurement Units
One measure of DO in water is parts per million (ppm) which is the number of oxygen molecules (O2) per million total molecules in a sample. Calculating the % Saturation is another way to analyze DO levels. % Saturation is the measured DO level divided by the greatest amount of oxygen that the water could hold under various temperature and atmospheric pressure conditions multiplied by 100.
What Is Being Measured?
DO probes respond to the partial pressure of oxygen in liquid or gas being measured – they measure the “pressure” of oxygen rather than concentration. All of the oxygen entering the probe is consumed at the cathode where it is electrochemically reduced to hydroxyl ions producing an electrical current within the probe:
Since all oxygen entering the probe is chemically consumed, the partial pressure of oxygen in the electrolyte is zero. Therefore, a partial pressure gradient exists across the membrane and the rate at which oxygen enters the probe is a function of the partial pressure of oxygen in the gas or in liquid being measured.
When a probe is placed in air saturated water, the current it produces will not be affected by the temperature or salinity of the water. The DO concentration in the water, however, will vary with temperature and salinity. Because it is convenient to report DO concentration in mg/L or ppm, it is necessary to adjust for temperature and salinity of the water to get correct readings in these units. If DO were to be reported in terms of partial pressure or % Saturation, then temperature and/or salinity compensation for oxygen solubility would not be necessary. Most probes are temperature compensated – i.e. they convert the “partial pressure measurement” to mg/L of DO at whatever temperature the water happens to be at for a given salinity and barometric pressure.
Test Results
So let’s see what happens in a standard hydroponic solution. For your consideration, I started with standard tap water. Three gallons of tap were placed in a 4 gallon bucket and allowed to stand for 48 hours. The parameters of the water after 48 hours were the following:
pH: 7.52 units
Conductivity: 376 uS
Temperature: 18.0 °C
DO: 9.43 ppm
Alkalinity: 80 ppm
Total Hardness: 220 ppm
Calcium Hardness: 110 ppm
Conductivity, pH, DO and temperature measurements were made using my Oakton meter collection. All the meters were calibrated prior to use. Alkalinity, and calcium hardness tests were performed with a Taylor titration kit, and total hardness was performed using a pool and spa test strip. For the DO meter, atmospheric pressure was set at 760mm Hg, and salinity was adjusted throughout the testing to compensate for the addition of nutrients. Salinity reading were set at 0.1 ppt (parts per thousand) for plain tap, 0.7 ppt for dilute lucas, and 1.2 ppt for full strength lucas. I assumed a conversion factor of 0.7 for calculating the salinity measurements from the EC readings.
For the first round of testing I started with a standard WalMart Aqua Culture dual outlet aquarium air pump (for 20-60 gallon aquariums). The pump is max rated at 1200 cc/minute. I decided to test the pump using a Topfin 4” diameter airstone (blue ceramic standard run of the mill stuff), a bare tube, and a Hydrofarm 3’ flexible air diffuser. All tests were run for 60 minutes, and parameters were recorded at 0, 10, 20, 30, and 60 minute marks. I tried to maintain a constant temperature of 18°C for the entire duration of testing using a frozen bottle of water to keep temps stable.
Beginning with the straight tap, I added the Topfin ceramic airstone and recorded parameters for 60 minutes. After 60 minutes, I added a dilute Lucas formula (0-4-8) using AN Micro and Bloom and pH adjusted to 5.66. The test was again run for 60 minutes and parameters were recorded. After this test, I bumped the nutrient solution to full strength Lucas (0-8-16) and continued the test, all the time using the Topfin airstone. The purpose of this test was to determine the effects of nutrient concentration (salinity) on DO concentrations.
Following completion of the full strength test, the Topfin ceramic airstone was removed, and a bare 1/8” diameter tube was placed on the bottom of the bucket. Again, parameters were recorded until the test was complete. Following completion of this test, the Hydrofarm flexible diffuser was added to the airline and the run for another 60 minutes. The final test involved adding 27% H2O2 at a ratio of 2ml/gallon to the full strength Lucas solution. Testing was conducted for 60 minutes and parameters were recorded.
The H2O2 I used was 27% Baquacil pool and spa oxidizer. $20/gallon. The MSDS sheet indicates it’s 27% H2O2 and 73% distilled water. There don’t seem to be stabilizers in the stuff from what I’ve found, but they may be there in minute concentrations and omitted on the MSDS.
The results of testing are interesting, but not conclusive. Since this was done on a solution with no oxygen demand (i.e. no roots absorbing oxygen), It’s difficult to determine the effects of oxygen demand at this time.
At this point, you’re probably saying just shut the fuck up and tell us the results.
Without further adieu, the winner of test #1 was the bare tube, followed by the Topfin airstone and the flexible diffuser. A side note is the bare tube was the loudest while the Hydrofarm difusser was the quietest. Adding H2O2 to the solution does increase DO to supersaturation levels (max 122%) at the 2ml/gallon application rate. I’m currently testing the H2O2 in my reservoir with a 3 week old flowering plant to test the rate of oxygen consumption. It looks like the supersaturation levels diminish to standard saturation levels within about 2-3 hours of application. It appears H2O2 has little to no effect on pH or conductivity, so adjustments should not be necessary once applied.
Attached is a table showing the results of Round 1 testing.
Lemme know what you think.
buddin_904
Member
sweet thread
Thanks buddin,
I plan on doing the testing using my scrog cab Cirtal gal as a guinea pig starting next week.
I'll do the same tests with the bare tube vs. airstones and H2O2 and also try to look at depeltion rates once the air or H2O2 goes away.
I plan on doing the testing using my scrog cab Cirtal gal as a guinea pig starting next week.
I'll do the same tests with the bare tube vs. airstones and H2O2 and also try to look at depeltion rates once the air or H2O2 goes away.
budshoteyes
Member
Mmmm!
Should I throw away my air stones and diffusers. I must say I'm totally surprised by those results.
Should I throw away my air stones and diffusers. I must say I'm totally surprised by those results.
If you want stealth, keep the diffusers. The bare tube is much louder. The Topfin seemed to produce the most spray above the waterline.
My subjective 2 cents.
My subjective 2 cents.
budshoteyes
Member
I had always thought the science behind diffuser air bubbles was more equals more oxygen exchange. The bubble supposedly exchanges oxygen for carbon dioxide as the bubble rises with the result of oxygen in the water and carbon dioxide above the water surface.
This deserves more investigation
Thanx Sgt Stedenko
This deserves more investigation
Thanx Sgt Stedenko
budshoteyes
Member
The waterfall aeration method should be tested....crossing fingers,hoping this natural method of exchange will be tested sometime in the near future!
yeah man, quite right, ive been using Oxy+ (17.5%) from growth tec & hydrogarden, i wouldnt use anything lower in strength than this, im gonna get my self some 35% food grade, not into stabilisers either.
Cheers bro!
I too find it wierd on the Tube test, i better read back a little! ah OK, I expected to see higher ppms of DO than was seen from the H2o2 tests. Im not fully understanding the %'s at the moment, need further working. be good to see some Oxy+ test strips put up against the meter.
Were all tests done in different buckets? i assume they were.
Anyway its nice to see some numbers for a change. I think sigle open ended tubes for DWC would be asking for trouble, that would soon get swamped by roots & prolly go anerobic, good for clear Res's though, i wouldnt be willing to put it to the test. Too noisey too, more agitation/impact at the surface than diffused bubbles, which surprises me as its more concentrated to one spot. I bet a couple of sprayer/shower powerheads would be even higher DO.
Great job Sarge k+
Using an Oxydator with the H2O2 for a constant release of pure O2 bubbles might be a good test too, as you wouldnt get as much dissipation etc. Just re-fill Oxydator to keep DO levels at a set level! sure that would help keep DO levels up.(maybe a combo of both adding it & use of Oxydator)
Also id wanna see differences in days of bubbling air rather than hours, see what difference that made, work out DO dissipation timings etc.
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hazydreams
Active member
sarge-
im really interested in how long a super saturated mixture can be kept as such. you stated that in 2-3 hours the h2o2 is back to say 100% level down from 120%. with out over complicating things, im wondering if the bubbling action of say the diffuser or bare tube actually makes the super saturated condition level off faster (Back to 100%) due to the bubbling out of the O2 in the peroxide mixture or if it holds it super saturated longer due to additional o2 being added. Im seriously considering a daily/(how ever long i can go cuz im lazy like that) addition of peroxide instead of the addition of aquasheild to my res......
I need empirical results from a test like this to change my mind. call me a skeptic.
im really interested in how long a super saturated mixture can be kept as such. you stated that in 2-3 hours the h2o2 is back to say 100% level down from 120%. with out over complicating things, im wondering if the bubbling action of say the diffuser or bare tube actually makes the super saturated condition level off faster (Back to 100%) due to the bubbling out of the O2 in the peroxide mixture or if it holds it super saturated longer due to additional o2 being added. Im seriously considering a daily/(how ever long i can go cuz im lazy like that) addition of peroxide instead of the addition of aquasheild to my res......
I need empirical results from a test like this to change my mind. call me a skeptic.
Scroggerman,
The test was conducted in the same bucket. The airstone was the only variable. Notice I went directly from the bare tube running about 100% saturation to the difusser and the saturation immediately dropped.
I personally use a Topfin stone and a flexible difusser in my SWC res. I too was suprised by the results. I plan on re-testing run #1 for repeatability.
The first test I did using my plant, I added 2ml/gal to my res. Before addition, I had 8.88 ppm of DO. After addition, I shot up to 12.44 ppm, but was back to below 9 ppm after 2.5hours.
The test was conducted in the same bucket. The airstone was the only variable. Notice I went directly from the bare tube running about 100% saturation to the difusser and the saturation immediately dropped.
I personally use a Topfin stone and a flexible difusser in my SWC res. I too was suprised by the results. I plan on re-testing run #1 for repeatability.
The first test I did using my plant, I added 2ml/gal to my res. Before addition, I had 8.88 ppm of DO. After addition, I shot up to 12.44 ppm, but was back to below 9 ppm after 2.5hours.
