# Exploring yeast as shrimp and plant food



## tiger15 (20 Aug 2018)

I have a jar of baker yeast left over from my days to make DIY co2.  Now I am using it to feed my daphnia culture.

I am wondering if I can just feed yeast directly to my planted shrimp tank.  Will shrimp eat yeast directly, or will yeast promote growth of biofilm shrimp feed on.  Baker yeast come in micro pellets similar to  fish food which commonly contain yeast as an ingredient anyway.

Also, will yeast consume DOC and make CO2 in a planted tank and thereby feed plants.  All the research I read about yeast is fermentation reaction under anaerobic conditions to make beer or bread.  What is the fate of yeast under aerobic condition in a planted tank.

So my question is whether it is safe and beneficial to feed yeast as a carbon source for plants and food for shrimp.


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## Edvet (20 Aug 2018)

In my mind safe but not benificial in noticable amounts.


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## zozo (21 Aug 2018)

tiger15 said:


> All the research I read about yeast is fermentation reaction under anaerobic conditions to make beer or bread. What is the fate of yeast under aerobic condition in a planted tank.



It's a kind of fungus cell and it consumes carbon hydrates, in nature we can find these very same fungus cells all over the place but maimly (higher numbers) in sugar rich invironments for example in flowers living off its nectar or on/in fruit. When it gets oxygen it breaths so to speak and produces CO² from the sugars it consumes. When it's deprived from oxygen and it can no longer breath than it produces alcohol from the sugars it consumes.

So from a baker point of view it consumes the sugar and the oxygen in the dough and produce CO² and the fungus farts makes the dough rise. From a brewers point of view it is deprived from oxygen in a closed bottle and it makes the alcohol..

So actualy it could very well be there already is a population of these fungus cells present in and around your aqaurium. Especialy if you have emersed plants flowering. If there is enough sugar for them to consume they will have a reproductive life cycle and will be present in numbers the invironment can sustain. Probably will be very little in an invironment with little sugar. 

So adding extra without any extra sugar isn't realy gonna do any good for them they probably wont live very long. Depending on the lifestock they might just get eaten as for example the Daphnia will. If shrimp fry does, i actualy do not know that, i guess so.

Adding yeast and extra sugar to an aqaurium? Also no idea if anyone ever tried i never realy gave it a thought.. Wouldn't be surprised if somebody did.. But i guess it wasn't a succesfull experiiment, in the end it produces more waste than CO².


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## tiger15 (21 Aug 2018)

zozo said:


> It's a kind of fungus cell and it consumes carbon hydrates, in nature we can find these very same fungus cells all over the place but maimly (higher numbers) in sugar rich invironments for example in flowers living off its nectar or on/in fruit. When it gets oxygen it breaths so to speak and produces CO² from the sugars it consumes. When it's deprived from oxygen and it can no longer breath than it produces alcohol from the sugars it consumes.
> 
> So adding extra without any extra sugar isn't realy gonna do any good for them they probably wont live very long. Depending on the lifestock they might just get eaten as for example the Daphnia will. If shrimp fry does, i actualy do not know that, i guess so.
> 
> Adding yeast and extra sugar to an aqaurium? Also no idea if anyone ever tried i never realy gave it a thought.. Wouldn't be surprised if somebody did.. But i guess it wasn't a succesfull experiiment, in the end it produces more waste than CO².



When I was making DIY CO2, I actually thought about adding sugar and yeast directly to the tank, as DIY CO2 is so tedious that I gave up after a few weeks.  But I couldn’t find any answers in researching the idea.  The other thread mentioned about adding citric acid as liquid carbon, so adding sugar + yeast isn’t a crazy idea.

I actually experiment feeding yeast to fish fry, and they will jump for it, but the pellets that don’t get eaten right away will dissolve and turn milky.  Daphnia are filter feeder and yeast is perfect filter food.  I’m not sure if shrimp or shrimplets can consume yeast in the water column.  Even if they don’t, won’t yeast enrich the bio film shrimp feed on?


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## dw1305 (21 Aug 2018)

Hi all





tiger15 said:


> When I was making DIY CO2, I actually thought about adding sugar and yeast directly to the tank,


I think the issue would be that the sugar has a really high <"Biochemical Oxygen Demand"> (BOD) and you risk having a huge microbial bloom that de-oxygenates your tank. The yeast will also contribute to the BOD, both via respiration and the increased population of organisms that consume it. 

*Theoretical bit*
You don't need to know this bit, but it is pretty useful when you are considering adding things, (novel foods etc) to the tank that you aren't sure about. 

If you want to know roughly how polluting a substances is likely to be, you just think about its sugars and protein content. Sugars and proteins are basically the "low hanging fruit" of microbial substrates, where the microbes don't have to "work" to retrieve energy (or fixed nitrogen) from them.

The chemical formula of a sugar is below (this is glucose, sucrose is a glucose and a fructose). The oxidation reaction will give you a <"Theoretical Oxygen Demand"> (THOD) and because we are talking about a dissolved sugar, THOD = Chemical Oxygen Demand (COD).    

C6H12O6 + 6O2 > 6CO2 + 6H2O and ThOD = (6 Mo2) / (M C6H12O6)  which is 180/192 = 1.07

The BOD will be a bit lower, but if you go with every gram of sugar consumes one gram (1000 mg) of oxygen you aren't far wrong. As a comparison these are the <"BOD figures for  agricultural wastes">.

Oxygen saturation in the tank is likely to be no higher than 10mg L-1, so adding a 10gmg L-1 sucrose solution (1g in 100 litres of water) will potentially consume all the oxygen in the tank water, and you can see how dangerous a small addition of sugar is. 

cheers Darrel


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## dw1305 (21 Aug 2018)

Hi all,





tiger15 said:


> Daphnia are filter feeder and yeast is perfect filter food.


You can feed your _Daphnia _on yeast, it is very nutritious and _Daphnia_ feed by filtering any particles in a certain size range from the water column. 

The only issue is back to the pollution one and "boom and bust", and you have to be very conscientious about harvesting the _Daphnia_, water changes etc. 

I don't keep a _Daphnia_ culture as such any more, I get enough from the water butts, but when I did feeding them very sparingly with <"gram flour and paprika">, and adding a snail and some hay to the culture, reduces maximum productivity, but gives much more stable cultures.

cheers Darrel


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## tiger15 (21 Aug 2018)

Darrel,  

The BOD is a good explanation on why it is a bad idea to add sugar directly to tank water.   The equation says that 6O2 is consumed to produce 6CO2, so any attempt to make CO2 by consuming O2 is a zero sum game with no net benefit but potential harm. 

I cultivate daphnia in outdoor tubs fed mainly by green water, and only occasionally supplement with yeast as treat.  The green water is sustained by topping the tubs with nutrient rich WC water from indoor tanks.


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## dw1305 (21 Aug 2018)

Hi all, 





tiger15 said:


> The BOD is a good explanation on why it is a bad idea to add sugar directly to tank water.


BOD is really useful concept, unfortunately it isn't something you can measure easily.

There are some more BOD bits in this thread on <"PlanetCatfish:Wood for tanks"> and in the linked <"Aeration and dissolved oxygen in the aquarium">. 





tiger15 said:


> The equation says that 6O2 is consumed to produce 6CO2, so any attempt to make CO2 by consuming O2 is a zero sum game with no net benefit but potential harm.


That is right, respiration just converts one molecule of oxygen to one molecule of CO2 (C6H12O6 + 6O2 → 6CO2 + 6H2O).

If you want more CO2 you have to add it, either via compressed gas or the acid ~ carbonate reaction etc. 

Plants are net carbon dioxide consumers (and oxygen producers (6CO2 + 6H2O + light energy = C6H12O6 + 6O2)) because as they <"photosynthesise"> the "spare" CO2 is incorporated into plant tissue. 





tiger15 said:


> I cultivate daphnia in outdoor tubs fed mainly by green water, and only occasionally supplement with yeast as treat. The green water is sustained by topping the tubs with nutrient rich WC water from indoor tanks


Perfect, green water is the best _Daphnia_ feed.

cheers Darrel


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## ian_m (21 Aug 2018)

Quite a few people, using DIY yeast CO2 reactors, have ended up dumping the contents of their reactors into their tanks, promptly wiping out everything in the tank. I assume due to sugar depleting all the oxygen rather than the yeast causing issues.


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## Edvet (21 Aug 2018)

When was young and ignorant i dumped a whole package of dried bakers yeast in my 500 liter tank, quite milky, no effects


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## ian_m (21 Aug 2018)

Edvet said:


> When was young and ignorant i dumped a whole package of dried bakers yeast in my 500 liter tank, quite milky, no effects


No sugar, which as Darrel, explains is what causes the issue.


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## Edvet (21 Aug 2018)

Yup, just to show yeast is harmless.


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## tiger15 (21 Aug 2018)

Edvet said:


> When was young and ignorant i dumped a whole package of dried bakers yeast in my 500 liter tank, quite milky, no effects


When you feed yeast to daphnia, you place enough yeast to turn the water milky, and the daphnia will clear it up.  Daphnia has been employed to clear up green water or hazy water from bacterial bloom by placing in a fine net to prevent  getting eaten by fish.


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## Edvet (21 Aug 2018)

It was almost 30 years ago, i've learned in the meantime.......


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## zozo (21 Aug 2018)

Few years ago there was a member here at UKAPS who got a phonecall from his wife that fish were dying and what to do? He raced home saw indeed dead fish and did a water change and still a few fish beyond help after that.. Aftre questioning his 5 or 6 year old son the litlle rascal confesed he threw in a glass of some kind of sweet soda drink, i forgot it's name but it's quite a popular kids drink in the UK. I never heard of it, got curious and looked it up.
But i bet the thread can be found back with the name of that stuff.

Than it likely must have been the sugar killing a lot  of his fish.. I not sure if that idea ever surfaced in that thread..

I never knew it was that nasty in an aqaurium.. Only kinda always felt you beter don't.


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## zozo (21 Aug 2018)

It was Vimto! And @AverageWhiteBloke was victimized by it and not his son but little nephew...
https://www.ukaps.org/forum/threads...l-hd-video-with-soundtrack.48546/#post-477132


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## tiger15 (21 Aug 2018)

ian_m said:


> Quite a few people, using DIY yeast CO2 reactors, have ended up dumping the contents of their reactors into their tanks, promptly wiping out everything in the tank. I assume due to sugar depleting all the oxygen rather than the yeast causing issues.



I believe it can happen easily.  I experimented with yeast reactor for a few weeks before switching to pressurized CO2.  The air hose that is intended to drive CO2 can instead drive sugar water and alcohol into the tank if it touches the liquid in the bottle.  It can also go the other direction by back siphoning tank water into the bottle.  The fermentation process comes in spurts and the pressure built up can fluctuate, so can the liquid level.  So even if the air hose level is set above the liquid, it can change.  Many DIY CO2 skip the check valve and the second stage gas knock out bottle for simplicity,  and disaster is waiting to happen.  It happened to me briefly and I decided to give up.


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## AverageWhiteBloke (21 Aug 2018)

Don't remind me 


zozo said:


> It was Vimto! And @AverageWhiteBloke was victimized by it and not his son but little nephew...
> https://www.ukaps.org/forum/threads...l-hd-video-with-soundtrack.48546/#post-477132



Sent from my STH100-2 using Tapatalk


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## zozo (21 Aug 2018)

AverageWhiteBloke said:


> Don't remind me
> 
> Sent from my STH100-2 using Tapatalk


Sorry.. Your story came to mind with the above sugar explaination..


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## AverageWhiteBloke (21 Aug 2018)

Still not over it, I loved those fish. Time is a great healer though. maybe one day I'll see the funny side.  Didn't realise it was the sugar though. When I looked through the list of ingredients potassium sorbate was in the frame. From what I understand its used to prolong shelf life of products so wondered if this had killed off the beneficial bacteria and caused a spike maybe.


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## AverageWhiteBloke (21 Aug 2018)

I think I use to use Potassium Sorbate when I was home brewing wine and beer after fermentation had completely finished to stop secondary ferment and so it would keep when bottled. That's what made it stand out for me.


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## rebel (22 Aug 2018)

This gives me an idea how to sterilise plants from snails..... One could incorporate the sugar method into their quarantine from snails .


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## dw1305 (22 Aug 2018)

Hi all, 





AverageWhiteBloke said:


> When I looked through the list of ingredients potassium sorbate was in the frame. From what I understand its used to prolong shelf life of products so wondered if this had killed off the beneficial bacteria and caused a spike maybe


It is in the Vimto to stop micro-organisms growing, but it doesn't have much effect on bacteria. Potassium sorbate is <"E202">.





AverageWhiteBloke said:


> use Potassium Sorbate when I was home brewing wine and beer after fermentation had completely finished to stop secondary ferment


It is much more effective on yeasts and moulds.

Vimto itself is fairly low in sugar by soft drink standards, <"4.7g in 100cm3"> (although it may have been more sugar rich in the past, but now has a sweetener added as well, possibly because of <"changes in legislation">). 





AverageWhiteBloke said:


> Still not over it, I loved those fish.


I was going to suggest that an interesting experiment would be to pour the present formula and "diet" versions into identical tanks and see if they have the same effect, but maybe not.

cheers Darrel


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## dw1305 (22 Aug 2018)

Hi all, 





rebel said:


> This gives me an idea how to sterilise plants from snails..... One could incorporate the sugar method into their quarantine from snails .


You could try carbonated water, it doesn't tend to kill the snails, but it gives a quick "knock down" effect so that you can remove small snails from moss etc.

cheers Darrel


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## AverageWhiteBloke (22 Aug 2018)

Maybe an interesting experiment Darrel but I would suggest not doing it with a breeding pair of £400 blue cobalt Discus like I did.

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## tiger15 (22 Aug 2018)

dw1305 said:


> Hi all, You could try carbonated water, it doesn't tend to kill the snails, but it gives a quick "knock down" effect so that you can remove small snails from moss etc.
> 
> cheers Darrel


Amano discovered accidentally that CO2 can enhance plant growth one day returning  home from a bar and poured a can of carbonated water.  I don’t think carbonated water will knock down snail selectively.  With sufficient concentration, it will knock down both fish and snail.  It’s not hard to remove snails if you can locate them, best done by laying out food trap.


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## dw1305 (22 Aug 2018)

Hi all, 





tiger15 said:


> With sufficient concentration, it will knock down both fish and snail.


Good point, it would kill all the fish first. 

I should have said that this is only for plants outside of the aquarium, where you can seal them in a container of carbonated water.

cheers Darrel


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## rebel (22 Aug 2018)

Hey guys when I sterilise plants for quarantine, there are no fish to worry about. Need to kill snails selectively and keep plant safe.


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