Carbon dosing - method testing started

So, can I ask the question on what the proper way to switch from vodka dosing to bio-pellets would be?

 

I have never done that Sacul
I have switched from Bio Fuel over to Vodka
and if it where me, what I would do is

gradually reduce the dose of vodka, whilst running the bio pellets
as the pellets can take a short - medium term time to kick in

thus if I was going to do it on my reef set up, that I am currently dosing 2 mils per day

I would drop to 1.5 mil per day, for a couple of weeks, whilst monitoring conditions and if algae started becoming an issue, or my Salifert tests indicated I was starting to develop a Nitrate issue, then I would consider increasing the dose again .
then a couple of weeks at 1.0 mil per day
then a couple of weeks at 0.5 mil per day

there after I would hopefully be able to rely on the pellets
it will have taken 6 weeks to get from 2 mils down to 0

it took about that long to get up to 2 mils so going back down in the same manner, seems a logical starting approach to me

Steve

 

On the same subject, what about going from GFO to biopellets? I know you can run them at the same time, but I'd like to eventually limit the GFO to hardly any at all since I don't believe I have a large source of phosphate going into the tank. How would you recommend eliminating the GFO?

 

Hi lynnmw

as its not a carbon source substitution, you can eliminate the GFO and swap to pellets in one go
although many people have found they need to run both
the pellets or rather the bacteria that the pellets help generate, can become nitrate limited, which means , if all the nitrate is used up, but there is still a surplus of phosphates, you cannot generate the additional bacteria that just deals with phosphate


basically, if your reading zero on nitrate test kit, but still have an abundance of recurring micro and film algae , then that is a signal that you will need to run GFO in addition to the pellets.

 

time for another sub experiment


the most green covered top rock, at present resides in the GFO run set up


so I have swapped that rock with the rock that previously became cleaner asc a result of relocating to Bio Pellet tank (from Bio Fuel tank)

and here is where it lived


basically, I have swapped those 2 rocks around this morning

the cleaned off rock , now in GFO set up


the GHA covered rock, now in the pellet set up

additional
to eliminate the effectiveness of the CUC this time around
2 snails - here is an image of 1 of them, have both been moved out and put into the most algae plagued, bio fuel set up

this image was taken whilst it was still in pellet set up - hence the clean'ish sand bed






there are 2 things I will be studying here
1 - will the GHA fade away in the absence of the CUC
2 - will conditions improve in the bio fuel set up - are these a pair of super snails?



pic of bio fuel run tank , complete with 1 of 2 new residents
so we can see if the snails, rather than the conditions are what's making biggest difference
Steve

 

LOL @ super snails. If they turn out to be so, you should breed 'em and sell them for a pretty penny.

Thanks for the reply on switching from vodka to bio-pellets. That is pretty much what I was thinking as well, however, I have read that reducing vodka can lead to cyano outbreaks. That would be my only concern, however, I feel that the bacteria that feeds off of the vodka would soon occupy the bio-pellet reactor.

Perhaps as a last experiment, you would think about adding fresh pellets in a reactor to the vodka setup, and following your suggested method, see what happens?

 

That's good input Sacul
definitely something I will try out

need to perform tests a second time as they are before that though
want to eliminate different light levels as a contributor
so I will eventually be stripping all 4 tanks down
mixing up the rock, and the sand, sharing it out again between the 4 tanks
and then moving Vodka dosing to tank 1 - GFO to tank 2 , Pellets to Tank 3 and Bio Fuel to tank 4

if we get similar results second time around
then I will be trying the wean off the Vodka and gradual move to Pellets in my own reef tank


Steve

 

Thanks for the info! I don't have any micro at the moment but I do run GFO constantly so I'm not sure what I would have without it running. Nitrates are at 0 though but that might be due to my cheato in the sump.

 

Your welcome

many reef keepers are prompted to either adding or changing GFO in relation to the frequency of glass scraping

so my suggestion would be
if your currently scraping once per week
and you change over to bio pellets, shortly after that, you find, you probably need to scrape the glass a bit earlier than your normal routine
then that would be a good signal to also utilise GFO in addition to the pellets IMO

Steve

 

OK, I've analyzed the images Steve took using the method described a few days ago. Basically, Steve took an image of a white cap, in each of the tanks, and we analyzed the color content to look for evidence of decreased light transmission in any of the tanks. Blue light penetrates water easily, however, as you shift more towards green and then red, the light tends to scatter. Pure water will tend to have a blue hue and scattering will give the water a yellow hue, which is a mix of red and green. So, we looked at the green and red content in particular. The red being the most important, as it is the most definitive evidence of scattering and therefore decreased light penetration.

I first analyzed the jpegs Steve posted and the results seemed fairly conclusive. However, there were some issues, for example, the jpeg format itself can shift the colors some. And I was also worried, that algae growing on the side could block some of the blue reflection from the sides and maybe add some green reflection, as algae is green. So, I asked Steve to scrape the sides and try again. This was probably a mistake in retrospect, as the scraping may have influenced the clarity for a number of reasons, and added some ambiguity, but it is what it is.

To get around potential differences in blue levels, perhaps due to reflection, or slight differences in camera distance etc.. it is possible to calibrate the images based on the blue channel. This assumes that the blue level should be identical between all images, which if all things are equal, it would be.
However, evidence suggested it may not be. So, I'll present both calibrated and uncalibrated images. I guess, you'll have to decide for yourselves if calibration is justified, or not. I think an argument could be made either way.


Anyways, here are the red content results.

No image has an exact consistent color. So, I've constructed 95% confidence intervals for the average mean value of the pixels in the sample. That basically means based on the sample, we are 95% confident that the actual mean value of the red pixels lies somewhere in this interval. The intervals are represented on the graph as vertical bars and the interpretation is if there is overlap in values, then there is not definitive proof that the values are different. Higher levels represent more red in the image. Also, while these values tend to jump around, remember, we are trying to detect very subtle differences, so there is an uncertainty and sampling error factor.


Here is the results from before scraping, using the uncalibrated image.
Here, the biopellets appear to clearly have the least red content and therefore likely have the best light penetration. The biofuel and GFO, the most, but no significant difference between the two and vodka, second to lowest.



Here is the same data, but after calibration. Again it appears that the biopellets have the least red content, although the differences are a bit smaller. Also after calibration, the GFO value drops proportionally and appears more similar to the vodka, but the biofuel remains proportionally high.




After scraping, the results are similar, with the uncalibrated data, however, the biopellets aren't quite as low, and the GFO is hanging in between the vodka and biofuel.


However, where it gets a little fuzzy, is with the calibrated data from after the scraping. Here, the biopellets go (proportionally) up quite a bit and the biofuel and GFO goes proportionally down.
The GFO appears significantly less red than the biopellets and biofuel. There is no significant difference between the GFO, biofuel and vodka and the biopellets are not quite significantly higher than the vodka, but very close.



So, the last result adds a little ambiguity, however, overall, the evidence mostly does not support the hypothesis that there is less light penetration in the biofuel tank. I'm not sure exactly how to interpret the last result, so, you'll sort of need to do so yourselves. I think one thing we could do, is rerun in a few weeks after the tanks have settles more from scraping. Please let me know if you have any thoughts, or want to see more detailed data though.