Algae Scrubber and Carbon Dosing experiment?

[rygh]

Everyone always asks about the best way to reduce Nitrates.
This would definitively decide that. Or NOT.

But it might be possible to do some pseudo-scientific experiments to get some hints.

I am planning on decommissioning my algae scrubber, and starting vinegar dosing
some time next year. That puts me in a position to have some of the key equipment
and experience to do some of this testing.

BUT: Can we devise a test that will produce MEANINGFUL results???
It is not that simple.
And if not, or there is limited interest, the time and effort is not really worth it.

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Key questions to try to answer:
1) Can an Algae Scrubber effectively reduce Nitrates?
2) Can an Algae Scrubber reduce Ammonia such that it does not end up as Nitrates?
3) Can carbon dosing effectively reduce Nitrates?
4) Is one obviously better?

Two questions are needed for Algae scrubbers, since it there is disagreement
on exactly how they work. Either removing Nitrates directly, or removing Ammonia
such that the Ammonia->Nitrite->Nitrate cycle is broken.

Unfortunately, "effectively" is not quantifiable. Add that to the complexity of
the testing, and it is unclear what to do.

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Test setups:
1) Baseline tank setup
2) Algae Scrubber setup
3) Vinegar dosing setup

Vinegar dosing needs a skimmer, so to reduce variables, all should have it.
Same temp, flow, etc for each.
What is baseline? Empty tank? Live rock? Skimmer? Water changes?
Definitely no fish, or coral in the tanks. Way too many added variables.
But diverging from real tanks makes results less applicable.


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What to test????

Make up a fresh batch of instant ocean, or use normal tank water?
Add pure ammonia? Pure Nitrate? Pure phosphate? Mixture?
Add cubes of food - more realistic?

Ideally you would minimize variables and just add pure chemicals.
But with scrubbers and bacteria, that does not really work correctly, since
they need other elements or become limited.

Continually add, or just in the beginning?

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What are meaningful results???

Zero change is meaningful.
One being 10X better than others is meaningful.

But odds are they will not be hugely different.
And remember the measurements and test setups will have a BIG margin of error in them.
So what constitutes "effective?"
That might be the hardest question of all.

 

[rygh]

Rich:
You largely inspired this with your talk over the weekend.
I hope you have some insight.
Oh ... and I will let you do all the work.
@Thales

 

[nly04]

It will be great with less equipment and less maintain involve.

 

[sfsuphysics]

IIRC I believe when simple algaes end up consuming ammonia they give off hydrogen instead of oxygen as a waste product. Not that you would make any in significant quantities but, I don't think that's going to happen in the aquarium settings.

As for testing, absolutely have everything the same except for what you're doing (i.e turf scrubber or vodka). So skimmers on everything, and if you added additional volume for the water that flows over the scrubber make sure that exists elsewhere as well. But other than that leave the tanks bare

Then set things in motion, mix up a batch of salt water, exactly one batch since you don't want to tweak any variables. Then after you get your cycle complete in each, check the level of nitrates, it's best to have a 0 level do a "reverse water change" take a batch of water from a nitrate heavy tank, and replace that in the tanks, big one too! Measure the nitrates in each tank right after doing it (after water has mixed) it should be identical if you did everything in the same proportions, then record them daily while doing everything else, and see who "wins"

The problems I see however if that both the scrubber and the vodka require time to "ramp up", more so for the turf scrubber though, and in that same way you can't take an existing scrubber from one tank and put it on your test tanks because you're adding parameters after the fact.

 

[tygunn]

Good stuff! I'd say a bare tank with no rock is probably your best bet. I would imagine rock adds a variable that you may not be able to control as well (or at least has lot of unknowns in my mind). For the baseline tank, perhaps a simple hang on back filter? You'll need some kind of bio media to give the bare tank a chance to demonstrate its ability to process nutrients using a more traditional setup.

I imagine you could start up the experimental tanks using seed water from the same tank and then

I think the following three questions go together well:
1) Can an Algae Scrubber effectively reduce Nitrates?
2) Can carbon dosing effectively reduce Nitrates?
3) Is one obviously better?

The following question seems like it would be best answered with an experiment of its own, compared to a baseline traditionally filtered tank.
I think in this case you would want to start with a seeded, "effective" ATS from the last experiment. I'd imagine dosing pure ammonia to both tanks, and then measuring the ammonia, nitrite and nitrate levels over the span of a few days would be a reasonable approach. I've never really dumped pure ammonia into an established tank, so I am not clear on how quickly it would go through all the stages of the nitrogen cycle (ie would it be quickly converted to nitrite and nitrate such that you wouldn't see the conversion if you measured daily?).

 

[rygh]

Dang, ramp up time is not something I had really considered.
That can potentially skew the results to the point of uselessness.

For the scrubber, I was planning on using my existing living screen.
So no ramp up needed, other than for new nutrient levels.
With an existing algae base, that is usually 1-2 weeks.

For carbon dosing, I am not sure what the ramp up time will be.
I know you can get a big bloom within a day.
So the bacterial expansion is quick. But the total cycle to skimmer export
might be much longer. Especially if the bacteria have to die first.

I am not sure how to deal with that.

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Another problem with the comparisons is SIZE.
1) Algae scrubber screen size makes a big difference.
2) Amount of vinegar added and skimmer makes a big difference.

A giant scrubber would likely beat a tiny bit of vinegar, and vice versa.

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It may not be at all possible to see if one is "better" than the other.

 

[rygh]

Thinking more on the size/dosing issue, it is unclear if I can even get
meaningful data on each individually being "effective" at all.

For example, if I take my scrubber built for a 240G tank, and put it
on a small 10G test setup, and it reduces nitrates, does that really mean much??
Same with high vinegar dosing.

All I would be proving is that either method can reduce "some" nitrates.
Which seems like a big waste of time.

Hmmm.

 

[Merith]

As long as you have no livestock you should be able to test the carbon dosing without the slow ramp up as the main reason for that as far as I know is to avoid lowering the o2 to a dangerous point. Yah he bacteria needs down time to populate but can do so much faster than the small additions per week you would do in a normal tank.


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[tygunn]

I am guessing it wouldn't work to just put it loads more nutrients to equate a large tank's bioload (except concentrated). I've done a fishless cycle on a tank in the past and overdid the ammonia and the cycle wouldn't start until I significantly lowered the concentration.

Though the ats is made for a larger tank could part of the screen be covered to expose just enough for a 10g tank?

I'm not clear if there are hard set instructions for how best to do carbon dosing to set up that for a 10g tank.

As an aside, it might be interesting to study different carbon dosing regimes to see how much is useful to get the desired impact. Ie more than a rule of thumb. Similarly experiments on ats size could help guage how big of an ats is really needed.

I'd consider doing some of these experiments myself if I had a spot for them. Lol. My wife would be unimpressed if I filled the appt with test tanks.

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[rygh]

...
As an aside, it might be interesting to study different carbon dosing regimes to see how much is useful to get the desired impact. Ie more than a rule of thumb. Similarly experiments on ats size could help guage how big of an ats is really needed.
...

And interesting point.
For my old ATS, I started with what was on algaescrubbers.net website, and went from there.
I actually ended up with a scrubber about 1/3 the size recommended.

For my vinegar dosing, I was going to start with what Randy Holmes Farley recommended, and go from there.
But it might be fun to have more quantitative data.

 

[wpeterson]

I would be very interested in doing some experiments around DOC levels both in relation to skimming, macroalgae, and dosing.

Does anyone in the club have access to chemical analysis facilities than can measure total organic carbon (TOC) in a sample?

 

[rygh]

I would be very interested in doing some experiments around DOC levels both in relation to skimming, macroalgae, and dosing.

Does anyone in the club have access to chemical analysis facilities than can measure total organic carbon (TOC) in a sample?

I remember reading about some DIY thing.
White LED + UV LED + photo-resistor.
Some combination of transmitted light and florescence.
Good at measuring delta, but not absolute values.
Could not find it with a quick google search though.