Disolved Oxygen in our Reeftanks - Who else measures it ???

[Diesel]

Maybe someone else can double check me, but from a quick google scholar the numbers in this thresd seem to be pretty typical of reef numbers in the wild. Not bad or too low.

Doesn't seem likely DO in this thread is low enough to cause an issue...doesnt even seem to vary significantly.

Anyone else find similar or different conclusions?

Also the pic isnt clear...what meter is being used?

https://www.amazon.com/Extech-DO210-Dissolved-Oxygen-Meter/dp/B00SYIVFVI

You’re right, most time the DO are within range, only when hobbyist do stupid stuff it can become dangerous low.
For example bacteria/carbon dosing

 

[Belgian Anthias]

I prefer redox measurement for long range stability. Lack of oxygen will kill fish faster than any other one thing. When I used oxygen monitoring, it was tied into alarm that sent a text.

ORP reading reacts very slowly on changes of the DO saturation. There is no reliable relation between changes in ORP reading and the DO content. ORP measurement may give you a false sense of security. ORP reading can not be used to determine the free oxygen content!

 

[Belgian Anthias]

The amount of oxygen water can hold (saturation) is dependent upon water temperature, salinity and atmospheric pressure. As water temperature increases, the amount of oxygen the water can hold decreases. Likewise, as salinity increases, less oxygen can be dissolved into the water. At greater pressures, water can hold more oxygen. For example, more oxygen can be held in water (of equal temperature and salinity) in Miami than at the much higher altitudes of Denver.

DO may be supplemented by use of an aeration system. In an aquarium, this aeration system often consists of only a simple air pump, air tubing and airstone. While this type of system does not greatly increase the oxygen level by pumping air and in turn oxygen into the tank, it can help circulate the water and break the surface tension of the water to increase the rate of diffusion.

I do agree it is not directly the air coming out the airstone which will aerate the aquarium water. It will mix the water , bring bottom water to the surface and break the surface tension making gas exchange easy this way driving out gases as CO2, N2, which may be replaced by oxygen till saturation.
DO will not be supplemented by the aeration system directly but mostly by gas exchange on the surface.

 

[Belgian Anthias]

How effective a skimmer will be as a gas exchanger taking in account the limited surface area and contact with outside air?

If CO2 is effectively driven out this should show by comparing the pH of influent and outfluent.

 

[Subsea]

ORP reading reacts very slowly on changes of the DO saturation. There is no reliable relation between changes in ORP reading and the DO content. ORP measurement may give you a false sense of security. ORP reading can not be used to determine the free oxygen content!

For certain, there are corresponding effects to low oxygen and ORP will be effected. Just exactly how it is effected is more complicated than A plus B equals C. Perhaps your use of the word “reliable” changed the definition of “relation” to you but as I said, I prefer to use ORP to measure long range stability.

@Belgian Anthias
Would you agree, that stability in a reef tank is effected by oxygen content? Do redox measurements track stability in a reef tank?

 

[Subsea]

@Belgian Anthias

The link you posted is in a language I am not familiar with. Here is what @Randy Holmes-Farley says about REDOX:

ORP, at its heart, is very, very complicated. It is, perhaps, the single most complicated chemical feature of marine aquaria that aquarists will typically encounter. It is not hard just for aquarists who are not scientists. I had to learn a great deal about the electrochemistry of natural waters in order to write this article, and had help from a number of other chemists in understanding some of the principles that are usually swept under the rug. ORP involves many chemical details that are simply unknown, either for seawater or for aquaria. It involves processes that are not at equilibrium, and so are difficult to understand and predict. Even more daunting is the fact that the chemical species that control ORP in one aquarium might not even be the same chemicals that control ORP in another aquarium, or in natural seawater.

http://www.reefkeeping.com/issues/2003-12/rhf/feature/index.php

 

[PSXerholic]

Why you have large bubbles in your skimmer?
They suppose to look like a milky swirl in the reactor.

Ben, not really bigger bubbles. What I meant to say is that since the foam column looks always like a milky foamy column, if I reduce air inlet I can make the bubbles even finer and smaller. Actually so small that the foam in the neck becomes almost a cloud white stiff foam, white as a cloud ;-)

Air inlet fully open I consider the largest bubbles in the the body and neck, reduced air inlet gives me a very fine foam column.

So not really big bubbles ;-)

 

[PSXerholic]

The name says it all, dissolved oxygen.
O2 or Ho2 both have Oxygen.
Here a link what it it does,
https://www.fondriest.com/environmental-measurements/parameters/water-quality/dissolved-oxygen/

Awesome lecture here !!!!
Started reading it yesterday, thank you very much for this link!

 

[PSXerholic]

Here are a few findings from yesterday, where we had a power outage and I have in my setup not taken into account the delayed start of the skimmer after a power outage, hence I told the wife to turn off the skimmer in the morning.
When I came home in the afternoon I measured 7.9 and in some spots 8.0 !!!! After a few hours running, open air valve and with no Co2 scrubber, I measured 7.5 in the early evening.

That was not a controlled measurement, but it supports the theory that the skimmer actually helps to get oxygen out of the tank if too much air is induced. Well this is Room air! Measured the house and it was equivalent to the outside air concentration.
But I know I have higher C02 levels in the house, and with the skimmer unscrubbed, PH was lower yesterday as usual due to the fact of more Co2 that came in through the skimmer.

When I measure yesterday afternoon the healthy high DO levels, Ph was at around 8, with co2 scrubbing I do measure about 8.15 normally around that time.
Saying, that even with higher DO levels, you still can have higher Co2 levels in the water, reducing your PH.
I'm trying to say here, that even if you have a high PH, it would not necessarily mean, that you have high oxygen levels too!
These 2 parameter seems to work out in reality independent from each other.

I always have the Dieseltank in mind, where I know and have seen that our Reeferbud Ben, used to use outside air for the skimmer and had reduced hours on the skimmer operation.

I will testing towards a similar thing. I do not have the possibility easily to run outside air, but I will run the Skimmer with much less air today, and Co2 scrubbing to bring the PH up a bit over a day and measure the DO this afternoon to see if it did increase again to 7.9ish or slightly lower.
Then tomorrow, I will start to run the skimmer only from 11am-5pm and will monitor the DO level trending over the weekend.

 

[Forsaken77]

I also measured the DO on the Nitrate reactor outlet with 6.8 yesterday. Sure it's lower since the bacteria in the reactor consume oxygen for denitrification.
Wondering if DO along with Delta No3 (In vs. Out) can provide a better understanding of the Nitrate reactor performance..........

Doesn't a nitrate reactor use primarily anaerobic bacteria? Meaning it would strip less Oxygen from the water?

This is the main reason I have two 25 watt UV sterilizers for a 180, to improve redox.

 

[Belgian Anthias]

For certain, there are corresponding effects to low oxygen and ORP will be effected. Just exactly how it is effected is more complicated than A plus B equals C. Perhaps your use of the word “reliable” changed the definition of “relation” to you but as I said, I prefer to use ORP to measure long range stability.

@Belgian Anthias
Would you agree, that stability in a reef tank is effected by oxygen content? Do redox measurements track stability in a reef tank?

One of many other factors.. ORP tracks stability? When tomorrow morning ORP is 50mv lower or higher than this evening. What can this ORP reading difference tell me about the stability of the system? What may this ORP change tell me about the oxygen content? ORP reading is sensitive for organic pollution on the probe. What caused the ORP change? After cleaning ORP rises slowly to 100mv above the previous reading. Does this mean the ORP change was caused by polution of the probe? Is the quality probe calibrated on a regular base? What makes ORP reading a reliable parameter for monitoring and managing the system? For determining stability I need parameters on which I can rely on. How reliable is ORP reading? A sudden ORP change will tell something happened what influenced the potential and one may start to check all basic parameters including oxygen content. So I need an oxygen measurement to help me determine why ORP changed. Wouldn't it be better to invest in a good oxygen meter instead of ORP reading?

 

[DudeBruh]

Following. Great topic.

I wonder if a group of people who aimed at making their tanks as ultra quiet as possible; with the drains below water level in the sump, and returns below water level up top and everything else done to reduce noise and splashing took readings and compared to another group with a much more “ airaited” or noisy setup. How they would stack up

 

[Belgian Anthias]

I also measured the DO on the Nitrate reactor outlet with 6.8 yesterday. Sure it's lower since the bacteria in the reactor consume oxygen for denitrification.
Wondering if DO along with Delta No3 (In vs. Out) can provide a better understanding of the Nitrate reactor performance..........

A nitrate reactor? Do you mean a nitrification bio reactor ? This would explain 6.8 mg/l DO in the effluent of a not very active bioreactor. Do you put the water in a recipient before measuring? And did you mean nitrification instead of denitrification?

 

[pwilliaml]

I've read that oxygen in your tank is largely affected by the oxygen in your home. If your home is pretty tightly sealed and you have a lot of people exhaling CO2 into the air, your tank will be a direct representation of that. That's why people have added CO2 scrubbers to their skimmer air suctions, or even run a line to the outside to pull outside air into their skimmer. This also has a direct affect on the pH of your tank as well. I know that during the day when my pH is the highest, if I turn on my air bubbler next to the suction of my return pump for some bubble scrubbing in the tank, it will drive my pH down if I'm pulling air from in the house instead of from the outside. I've never invested in a DO meter, but you're making me wonder now. Ultimately if you're concerned about O2 in your tank, add a CO2 scrubber or run a line from outside to your skimmer inlet. Have you done direct comparisons between your DO outside to in your house, to in your tank? It would make sense if your house O2 levels were lower and your skimmer outlet was lower than the rest of your tank as the skimmer is mixing air from your home into the tank. Just my two cents.

 

[Subsea]

One of many other factors.. ORP tracks stability? When tomorrow morning ORP is 50mv lower or higher than this evening. What can this ORP reading difference tell me about the stability of the system? What may this ORP change tell me about the oxygen content? ORP reading is sensitive for organic pollution on the probe. What caused the ORP change? After cleaning ORP rises slowly to 100mv above the previous reading. Does this mean the ORP change was caused by polution of the probe? Is the quality probe calibrated on a regular base? What makes ORP reading a reliable parameter for monitoring and managing the system? For determining stability I need parameters on which I can rely on. How reliable is ORP reading? A sudden ORP change will tell something happened what influenced the potential and one may start to check all basic parameters including oxygen content. So I need an oxygen measurement to help me determine why ORP changed. Wouldn't it be better to invest in a good oxygen meter instead of ORP reading?

Considering that I said long range stability for ORP, I use it to indicate trends in change. The link I provided answers the questions that you posed and the answers are too complicated to get into the debate over it. Your use of do meter is an accurate measurement of a critical parameter. All intensive aquaculture facilities will track DO at all times. It is the single most important parameter in our reef tanks. I have used both instruments. Unless hardware has changed dramatically, both probes need frequent service with oxygen probe failure much more frequent because of membrane degradation. It has been a few years since I have used either. What is your experience with do probe service longevity?

With respect to investing money, which would I use. It would be DO.

 

[Subsea]

I do agree it is not directly the air coming out the airstone which will aerate the aquarium water. It will mix the water , bring bottom water to the surface and break the surface tension making gas exchange easy this way driving out gases as CO2, N2, which may be replaced by oxygen till saturation.
DO will not be supplemented by the aeration system directly but mostly by gas exchange on the surface.

IMO, the single most important thing to be taken from this thread is that dissolved oxygen in reef tank water does not happen because of the bubbles in your protein skimmers. Oxygen, carbon dioxide, and nitrogen all have two way streets to go from inert gas to dissolved gas. Differrent mechanism including partial pressure of gas in athmosphere along with saturation levels for each gas both of which are in dynamic flux to equalize.

The largest contributor to gas exchange in a reef tank happens at the water surface.

 

[Diesel]

Ben, not really bigger bubbles. What I meant to say is that since the foam column looks always like a milky foamy column, if I reduce air inlet I can make the bubbles even finer and smaller. Actually so small that the foam in the neck becomes almost a cloud white stiff foam, white as a cloud ;-)

Air inlet fully open I consider the largest bubbles in the the body and neck, reduced air inlet gives me a very fine foam column.

So not really big bubbles ;-)

Forgot what skimmer you have but my lifereef with the upgraded mazzei Venturi makes contact time to large as I can strip my tank from nutrients in a day or two.
As why my skimmer runs only a few hours during the day.
Night time 4 hrs NMB

 

[Dr. Dendrostein]

After all the chasing of numbers. What really determine successful, healthy, thriving reef tank is happy, healthy, sex crazy, corals.
Your children of the sea will show you that. IMO

 

[Captain Quint]

I'm lazy.

I use a Milwaukee MW600.

 

[Subsea]

I'm lazy.

I use a Milwaukee MW600.

What does MW600 do for your reef tank?