Maximising Dissolved O2

Nick72

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Hi @Geoffrey Rea @alto

I was following the thread below..

https://www.ukaps.org/forum/threads/long-term-filamentous-diatoms.61480/

... and in post #14 Geoffrey made an interesting observation regarding dissolved oxygen.

That an air stone or increased surface agitation could in fact reduce the over night levels of dissolved oxygen in an aquarium.

I didn't want to hijack the above thread, but at the same time this idea has now been banging around in my head for the last couple of days.

I'm hoping we might pick up where you left off.

I've been running an air stone from CO2 off to CO2 on in my tank to ensure enough dissolved O2 over night for my fish.

From Geoffrey's tests, at a certain point of plant mass / growth the air stone will be counterproductive in this respect.

Do we know how common this is? How much plant mass before you reach the tipping point?

My fish are fine with my status quo, but are there additional benefits of maximising over night dissolved O2 levels for the plants? Or for any other reason?

Testing for dissolved O2 doesn't look cheap, with meters starting at a couple of hundred pounds, and even test kits at the 40 pound range:

https://www.globaltestsupply.com/pr...MIsP7olZmn6gIVwRwrCh330gBQEAkYAyABEgJphPD_BwE

(And that's before international postage, customs issues and emails requesting Material Safety Data Sheets)

So before I go any further down this path, it would be good to understand the potential benefits of increased dissolved O2, beyond what it necessary for the fish?
 

Geoffrey Rea

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That an air stone or increased surface agitation could in fact reduce the over night levels of dissolved oxygen in an aquarium.

It does but I stock heavy on my tanks. Running the air stones/diffusers at night offers a bit more redundancy if say fish die using up o2 or Co2 runs out during a photo period without being noticed, reducing the biological means of o2 production.


That an air stone or increased surface agitation could in fact reduce the over night levels of dissolved oxygen in an aquarium.

It might, but only back to atmospheric equilibrium. Plus it’s constantly topping it up through surface agitation at atmospheric equilibrium... Again, another layer of redundancy should a filter go or something.

From Geoffrey's tests, at a certain point of plant mass / growth the air stone will be counterproductive in this respect.

Heavily planted is a subjective term. This is heavily planted to me:

1593443274577.jpeg


It’s also the tank I took the readings off. By the end of the photo period the surface was covered in bubbles as the water was saturated. This carried on way into the night:

1593443453279.jpeg
 

dw1305

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Hi all,
Running the air stones/diffusers at night offers a bit more redundancy if say fish die using up o2 or Co2 runs out during a photo period without being noticed, reducing the biological means of o2 production. ............It might, but only back to atmospheric equilibrium. Plus it’s constantly topping it up through surface agitation at atmospheric equilibrium... Again, another layer of redundancy should a filter go or something.
That one.

cheers Darrel
 

Geoffrey Rea

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it's probably best to stick with an air stone or good levels of surface agitation then.

‘Good’ surface agitation I define as this:

1593450486925.jpeg


1593450513441.jpeg


The waters surface isn’t being broken, but there’s rippling everywhere across the waters surface. It’s probably a bit more than what most people run when running Co2. All the high tech systems in the house run this as a standard 24/7. Low tech I’m happy to break the waters surface but it isn’t really necessary.

Running an air stone/raising a lily pipe at night on a Co2 injected system at startup has always matured the systems I’ve run quicker than if I didn’t. The prediction is the continual top up of o2 through surface agitation at night helps the substrate and filter mature quicker and handle waste faster during the early stages after initial setup. However, haven’t confirmed this yet as haven’t got access to a dissolved o2 meter and calibration fluid at the moment.

Originally wanted to compare three high tech setups at startup that would all be densely planted:

- One with no additional surface agitation at night
- One with additional surface agitation at night
- One with a Twinstar electrolysis unit running 24/7

It’s tiring and time consuming sitting up with a tank for twenty four hours though, calibrating for every data point.

Back on point though @Nick72 the other component is air stones/diffusers running at night change the flow pattern, helping ensure any spots that may get poor flow during the day have the possibility of getting water drawn through them at night. Running them on the back wall of the tank pictured in post #2 also lifted a lot of detritus up into the water column and into the filter intakes. With a lot of fish this is really helpful as just switching out the filter floss and pre-filter sponges weekly removed a ton of crud that would otherwise settle in the tank. Kind of good bang for your buck with regards to maintenance time.
 

jaypeecee

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Hi @Nick72
Testing for dissolved O2 doesn't look cheap, with meters starting at a couple of hundred pounds, and even test kits at the 40 pound range:

Are you able to obtain the JBL O2 test kit in Malaysia? This is what I use. It sells for around £12.99 (Pro Shrimp) here in the UK. Or, perhaps, you don't need to test dissolved O2 now?

JPC
 
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