# Small Daphnia culture



## idris (13 Nov 2019)

Having decided to try culturing some live food, although Vinegar Eels sound easiest, I thought I'd have a go at Daphnia.
There's no shortage of info online, so I won't go through much of the background - this is just a _here's what I tried_ journal, and ultimaely a _whether-or-not-it-worked_ journal.
My goal is to try to do this both on a small scale, and for as little money as possible.

As we have a garden pond ...




 

... this is where I sourced some water from, hoping it would yield enough Daphnia to get started.
The pond has a few fish in it, and being October, I didn't expect a large number of Daphnia from the start, but a bucket of pond water sat in the garage for about 3 wks with a heater in it, set to about 20°c, in the hope that the warmth would accelerate the Daphnia's reproduction.



 

Having borrowed an old microscope, with regular checking, I (think I) managed to identify daphnia in water from the bucket after about 2½ wks.



 

They're tiny little ****ers and don't stay still under the microscope, but I'm pretty sure I found some Daphnia, along with (probably) Cyclopse, Ostracods and Midge larvae.

In the meantime I filled a 2L plastic bottle with more pond water, to use as a green-water culture, with which to feed the Daphnia, and sat that on a window sill. That turned green, then cloudy, but I wasn't happy with that starting to smell a bit sulphorous after a couple of weeks, and I hadn't yet spotted any Daphnia, so I threw that out and started again.
And a request on Freegle got me a couple of free 5L demijohns, in one of which I will try to seed the culture.

Largely at Darrel's suggestion, I collected some dried grass from the edge of a local field, and have tied a small sheaf together with cotton. (I've tied it up just so it's easier to get out if I decide to.)



 

As I understand it, the grass helps both stabalise the water chemistry and provides a food source for infusoria and thefore the Daphnia. (Please feel free to correct me on this. )

On a cold, sunny, November morning, I filled half the demijohn with water from the bucket, and over the next half hour or so (so as not to shock any fauna) topped it up with water from my aquarium.



 

*Next:*
I'm in two minds about the degree to which I'll try to feed any Daphnia (and anything else that's in the demijohn). I can't spot any obvious fauna in the at the moment, but once I can, I'll try feeding with just green water. Depending on how that goes, I may try yeast.


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## Gill (16 Nov 2019)

Daphnia are so easy to look after. Feeding wise: Green Water, Spirulina powder and Bakers yeast is great(tiny amount and once water is clear again, they have eaten all the yeast).


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## jaypeecee (16 Nov 2019)

Hi Folks,

I've cultured Daphnia. The water in which they are kept needs to be oxygenated. If I remember rightly, their body starts to turn red (from clear) when oxygen level gets low. But, it's better not to use an air stone that produces a fine mist of bubbles. Apparently, the bubbles can get trapped inside their carapace and kill them. Unfortunately, I lost a whole batch of Daphnia this year back in August when we had the heatwave. They are not happy if the water temperature goes much above 25C. One other thing is that light encourages reproduction. Oh, and another, they are very sensitive to contaminants in the water. Tank water in which fish have been kept free of any medications should be fine.

JPC


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## jaypeecee (16 Nov 2019)

jaypeecee said:


> But, it's better not to use an air stone that produces a fine mist of bubbles.



I meant to add that airline tubing (6/4mm) connected to an air pump at one end and open-ended at the other is what is needed. Running this into the water at about 1 bubble per second should do the trick for a 2 litre container. Scale up accordingly.

JPC


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## idris (16 Nov 2019)

I've only spotted a couple of Daphnia in the demijohn so far and the water is still coloured, so no feeding yet.

I'd read that about oxygenation, but unless I've mis-remembered / misunderstood, Darrel was suggesting that was less than necessary. I figured I'd start without and see how it went.

I an wondering whether it's worth removing the plant matter that was in the pond water and has sunk to the bottom. Its a source of decay (negative) but may promote algae which the Daphnia will feed on (positive).


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## jaypeecee (16 Nov 2019)

idris said:


> I've only spotted a couple of Daphnia in the demijohn so far and the water is still coloured, so no feeding yet.
> 
> I'd read that about oxygenation, but unless I've mis-remembered / misunderstood, Darrel was suggesting that was less than necessary. I figured I'd start without and see how it went.
> 
> I an wondering whether it's worth removing the plant matter that was in the pond water and has sunk to the bottom. Its a source of decay (negative) but may promote algae which the Daphnia will feed on (positive).



Hi @idris 

Are you certain that the couple you spotted are actually Daphnia? I saw your video but it was a tad out of focus. I'm not being critical. It's not easy 'filming' Daphnia. They are unmistakable and swim with a jerky movement. I took the easy route with my Daphnia by buying live Daphnia from my LFS. For less than a quid, it was a no-brainer. It goes without saying that it's essential to use at least a magnifying glass to check any that you buy. You don't want to find other unwelcome critters in the bag! Almost from day one, the population of Daphnia grew and, at the same time, I was feeding them to my fish.

JPC


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## idris (16 Nov 2019)

I've identified Daphnia from the bucket with a microscope.
I can't guarantee what I've since spotted (with a magnifying glass) in the jar, but they look to be moving in the right way. They're bigger than Ostracods, and don't move like Cyclopse. 

I could probably get some from a LFS (though I've not seen them specifically amongst the live food) but I wanted to try seeding a culture from the pond  I may resort to buying some if this fails or takes too long.


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## idris (19 Nov 2019)

*6 days on*, and I couldn't initially see any life in the demijohn.
But then I spotted a significant number of creatures in the bottle I was culturing as green water.
A little more patience and I spotted a couple of inverts in the demijohn as well.

The reality is there's not a great deal of difference between the two containers at the moment - the water in both is green and both have decaying organic matter in them. So it's probably largely chance at the moment.

There seem to be three discernable types of inverts I can spot with a magnifying glass.
The first are visible as little more than dots, and a fraction of a mm long. These are the most prolific.
The second (left below) are the scarcest, and I may be Daphnia or Copepods. If anything, they have a slightly pink hue, which I think is evidence that they may be Daphnia feeding on bacteria, rather than algae.
The third, (right) looks more opaque and I'm pretty sure are Copepods.



The second and third are no more than 1mm long, and those on the left follow a slightly more eratic path.


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## Tim Harrison (19 Nov 2019)

Could be male and female cyclops.


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## zozo (19 Nov 2019)

idris said:


> Daphnia feeding on bacteria, rather than algae



They feed on much more than algae alone.  I keep Daphnia in a 100-litre tub in the garden that only contains dead leaf litter. The water is always crystal clear and all year round Daphnia in it. It's still is boom and bust, but there's always something in it. Sometimes it bursts from Daphnia other times it's less and it keeps going up and down like this. I never ever look after them with extra food or such, it's completely self-sustaining. I only take out some leaves that fell in if it looks like too much. The decaying leaf litter in it seems to provide enough food for them. At times the tub looks empty, but then they are all on the bottom under the leaf litter, a little wigle with the net to stir them all up ready to catch.


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## jaypeecee (20 Nov 2019)

Tim Harrison said:


> Could be male and female cyclops.



Those were my thoughts entirely.

JPC


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## MJQMJQ (21 Nov 2019)

From the video that looked like seed shrimp.If u can find greener dried grass it is better(higher nitrogen content for the algae) .The one with the pinkish hue is probably daphnia.
Low oxygen usually affects an entire population, coloring all animals reddish. https://www.ncbi.nlm.nih.gov/books/NBK2042/ 
Do you have an air stone in there?Green water is the most easily cultured with exposure to sun


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## idris (21 Nov 2019)

The "video" is only 3 frames and relatively low magnification, so don't read too much into it.

Greener dried grass? I'd understood that the stuff put in rodent cages was ideal, and I was under the impression that was definitely not green.

There isn't an airstone as there isn't a convenient mains socket near a convenient windowsill.


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## dw1305 (21 Nov 2019)

Hi all, 





idris said:


> Greener dried grass?


I think some people use the dried grass pellets you get for Horse, Hamster, Rabbit food etc. 

It is just a nutrient issue really, greener grass will have more sugars and proteins etc., but more power to pollute (a higher BOD). 

I use lawn cutting (in the summer) in buckets of water to encourage Mosquito larva and Bloodworms, they don't need high quality water, so it doesn't matter if you end up with low oxygen. 

I don't like my_ Daphnia_ cultures to be too productive, you tend to get the boom and bust, mainly because Daphnia have fairly high water quality requirements.  Adding dried grass (hay) makes the cultures tick over for longer. 

cheers Darrel


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## jaypeecee (21 Nov 2019)

idris said:


> There isn't an airstone as there isn't a convenient mains socket near a convenient windowsill.



Hi @idris 

You could try a battery-powered air pump. It wouldn't have to be powerful as you don't need the airstone as I explained previously. Without aeration, your chances of success are not good. I guess you could try a wide-topped shallow dish. This will maximize oxygen diffusion into the water but it may need to be topped up frequently to compensate for evaporation.

Good luck!

JPC


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## idris (22 Nov 2019)

*Failure #1 ... and possibly #2*

After a week+ without quite the progerss I'd hoped for, I happened to be passig a couple of LFSs and figured I might as well buy a bag of Daphnia as a comparison.
The first LFS had them in the fridge and it was dificult to see any movement in the bag. There had been a fresh delivery 48hrs previously, so I hoped to see some life, but being refrigerated could easily account for sedated critters. I went to the other LFS, whose bags were on the counter and filled with much more active Daphnia. (And they were 25p cheaper ... hey ... we're living in a time of austerity!)

Back home, as I had a second demijohn, I introduced the bag of shop bought Daphnia into freshly siphoned tank water in a similar way to introducing new fish. Warming up, then sowly adding just a little tank water. Working with a much smaller volume of water made this harder than with fish, but it was better than nothing.
I'd guess that there were easily more than 100 Daphnia bouncing around.

First thing of importance is that seeing bought Daphnia next to what I had from the pond, it was obvious that what I've been looking at in the first jar were absolutely _not _Daphnia. Daphnia are significantly bigger and can easily be identified with the naked eyer, whereas what I've mostly been observing till now could only be identified with at least a magnifying glass. (I'm still pretty sure I've identified Daphnia from the pond water with the microscope, but there were certainly not in significant numbers, compared to the Copepods.)

For various reasons, I set up the second demijohn in the garage. It's well insulated, so cool, but not cold, has some direct light, but not as much as in the house, and there is the option to plug in an air pump.
The one air stone I had produced a lot of small bubbles. Removing the airstone resulted in a lot of big bubbles. From what I've read, small bubbles are a bad idea, so I opted for big bubbles. The downside was that it made the water quite turbulent.

Come the morning, most of the bought Daphnia were dead. I'd estimate about 30 were left.





Meanwhile, the bottle intended as a green water culture had pleanty of cyclopse, and the first demijohn had pleanty of algae.





Some of the green water has been "fed" to the remaining shop bought Daphnia, and that will go back in the garage. If I can find an air valve, I'll also try to restrict the amount of air bubles / turbulence, just so I'm only changing one variable at a time.
I've also tried to remove as many of the dead Daphnia as possible. They could help nurish algae to feed the healthy Daphnia, or they could polute the water. I don't know which is more likely at this stage.


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## dw1305 (22 Nov 2019)

Hi all, 





idris said:


> The one air stone I had produced a lot of small bubbles. Removing the airstone resulted in a lot of big bubbles. From what I've read, small bubbles are a bad idea, so I opted for big bubbles. The downside was that it made the water quite turbulent.
> 
> Come the morning, most of the bought Daphnia were dead. I'd estimate about 30 were left.


It is the turbulence, they don't like it and it stops them feeding. 

If you add air it needs to be a *very slow* bubble rate. Personally I would worry about adding air, I'd just drop the water level so that it is in the wide bit of the demijohn and improves the surface area to volume ratio. 

cheers Darrel


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## idris (22 Nov 2019)

dw1305 said:


> Hi all, It is the turbulence, they don't like it and it stops them feeding.


I wondered whether that was the cause.


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## jaypeecee (22 Nov 2019)

Hi @idris

I cannot resist trying to help you. So, what is the temperature of the water that your new Daphnia are in? It may also be that, being in your garage, light is now too low. As regards the airflow, I originally suggested 1 bubble per second. In order to achieve that, you can fit a flow adjuster in the airline. You'll be able to see if the Daphnia are not getting enough oxygen by their colour.

You can still be successful with the 30 Daphnia that you have left.

JPC


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## idris (22 Nov 2019)

jaypeecee said:


> I cannot resist trying to help you.


Don't feel bad about that at all!!! Input from those with experience us very welcome.



jaypeecee said:


> So, what is the temperature of the water that your new Daphnia are in?


I've not measured that yet. As I understand it, low 20s C is about right, depending on the variety. (Though I have no idea whether I've actually got Pula or Moina.)



jaypeecee said:


> It may also be that, being in your garage, light is now too low.


It's not as dark as most - just not as bright as the kitchen windowsill. Considering others have talked about harvesting Daphnia from water butts, I'd be surprised if that killed off so many in less than 24hrs. I was under the impression that light was as much about photosynthetic infusoria as the actual Daphnia - yes/no? 



jaypeecee said:


> I originally suggested 1 bubble per second. In order to achieve that, you can fit a flow adjuster in the airline.


I remembered your 1 bubble recommendation, and was a bit concerned about the turbulence, but it was a choice between turbulence or small bubbles or no air in the first 24hrs. I just didn't anticipate turbulence having such a devastating effect so quickly. I've since dug through old boxes and found a valve which is fitted to the air line. It's now at slightly more than one bubble per second, but the Daphnia aren't getting buffeted around and are swimming freely. Depending how they do over night, I may dispense with the airline, increase the surface area (as per Darrel's suggestion) and move the jar indoors. 



jaypeecee said:


> You'll be able to see if the Daphnia are not getting enough oxygen by their colour.


They are quite pink at the moment. How quickly are they likely to loose that with appropriate dissolved oxygen levels?
I know O2 levels improve with decreased water temp - how significant is that likely to be? My guess is it's probably between 5C and 10C warmer in the house, depending on time of day.



jaypeecee said:


> You can still be successful with the 30 Daphnia that you have left.


Yeah - I've read of sustainable cultures from as few as 10, so I'm not giving up on this batch yet.


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## idris (24 Nov 2019)

*Failure #2 *
After another 24hrs, even more of the shop bought Daphnia were dead. So ...

*Start #2.5*
Again I was passing the LFS so decided to pick up another bag. I'm disapointed to say that my ambition for zero cost has gone out of the window as I have now speant a stomach churing £2.50. Whislt my children may have to go hungry for a few days as a result, I am looking at this as a long term investement. 
The LFS had taken delivery several days previously, so the live:dead ratio in the bag was nowhere nearer 1:1 than 1:0, but there were a decent number still alive and advice seems to be start with a small number ... and to go back when they have a fresh supply would mean a special trip and a resultant contribution to climate change.

I syphoned out as many dead Daphnia from the second demijohn as possible (the one without grass) and only added live ones from the new bag. (I may add some organic matter later.)
For convenience and better temperature (early evening, before the cenrtal heating goes on - about 18°C) I'm going to run this all in the house again, which will mean no air pump, just increased surface area.
I'm also going to be focussing on food for a few days:
1) A new bottle of green water has been seeded, this time with brocolli stem and frozen peas, and 50% of the water from the previous bottle.
2) I've mixed up some yeast solution from 5g of quick yeast, a pinch of sugar (to activate it) and about 100ml of water from the aquarium. Only about 5ml has gone into the demijohn so far, along with about 100ml of green water. The result is slightly cloudy and I'll have a look at the water clarity in the morning to judge how soon to feed again.


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## jaypeecee (24 Nov 2019)

Hi @idris

Here's a bit of bedtime reading:

https://www.caudata.org/daphnia/

JPC


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## jaypeecee (24 Nov 2019)

Hi @idris 

Please remind me about the water you are trying to culture the Daphnia in. Is it tank water, treated tap water, rainwater or what?

JPC


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## idris (24 Nov 2019)

I've read the Caudata page, though not recently. There may be bits I could do with rereading. (Grrrrrrr ...)

The daphnia are in tank water.
The greenwater was originally pond water, but has since been diluted with tank water.
We do have a water butt, but I've never got into the habit of using it for anything but gardening.


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## Basviola (24 Nov 2019)

I did not take the time to read all comments on this, but I just wont to drop five cents here, as I looked quite a bit into this some time back.

And the most important things I remember was this:

Some species of daphnia is less likely to collapse in a culture.
(Sorry I do not remember the name, but think it is the type that is among the biggest, that is the easier one to go with)

Airstone is essential

Overfeeding can collapse the culture.
About collapsing cultures, if they reproduce faster that what you need for feeding, it will obviously lead to a collapsing culture... So throw out daphnia or give away to friends if it gets to tight in there!

About feeding, most people have had success with yeast. And as mentioned only feed a little, and first again after water is clear again. Some reports good effect with 2 part yest to 1 part spirulina.


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## idris (24 Nov 2019)

Thanks @Basviola I think that concurs with everything I've read, exccpt the airstone: an air line is beneficial (though not an absolute requirement) but an airstone can be a bad idea as they tend to produce fine bubbles which get caught in the Daphnia shells, float them to the surface, where they get stuck due to surface tension.


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## jaypeecee (24 Nov 2019)

idris said:


> The daphnia are in tank water.



Hi @idris 

I have a few questions about your tank water:

1. What are the KH and GH of your tank water?

2. Was your tank water first treated with tap water conditioner before adding to your tank? If so, which?

3. Have you ever used a snail killer treatment in your tank or any treatments that contain copper sulphate?

That'll do for the moment.

We'll get to the bottom of this.

JPC


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## idris (24 Nov 2019)

The water should be fine.



jaypeecee said:


> 1. What are the KH and GH of your tank water?


I couldn't give you numbers (and don't have a test kit), but we have pretty hard water round here.



> 2. Was your tank water first treated with tap water conditioner before adding to your tank? If so, which?


Every water change (10%) is treated with conditioner in a 25L canister before adding to the tank - off the top of my head, I think it"s AquaCare Tap Water Conditioner. Whatever it is, I know it claims to deal with "heavy mwtals" so that shouldn't be a problem.



> 3. Have you ever used a snail killer treatment in your tank or any treatments that contain copper sulphate?


Only water, dechlorinator and ferts have ever gone in this tank (9yrs) and no ferts in the last 2-3yrs. (I've always had assassin snails to combat .... well ... snails.

The greatest risk with the tank water is probably NO3, but as I've been getting back into the habit of regular water changes (even if not filter media flushes) every week, and it a well planted tank with relatively few fish, even that is quite unlikely.

If you're thinking about contamination ...
The demijohn were second hand, and probably used for wine making. There was some residue at the bottom that I couldn't clean out, but have no idea what it was. I tried both formic acid and bicarb to remove it but neither made much difference. The jar was very thoroughly rinsed afterwards and no detergents were used.


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## dw1305 (25 Nov 2019)

Hi all, 





Basviola said:


> Airstone is essential





Basviola said:


> most people have had success with yeast.


 I think if depends what you want from your cultures. If you don't mind lower productivity you can use a less polluting food source.

You don't actually need added air, you just need to keep the water quality reasonably high, but this is difficult when you feed with yeast.

I've kept the same cultures (for at least the last fifteen years) and you can do this if you avoid boom and bust. It is a bit like keeping free range Chickens, rather than broiler house ones.

_Daphnia_ feed by sieving out particles of a certain size from the water column, they don't differentiate what that food particle is. Green algae, yeast, gram flour, spirulina  powder, paprika etc. all work because of the size of the particle. If you add dried grass it generates algae, rotifers and protozoa, of a suitable size, which the _Daphnia_ can then eat.

cheers Darrel


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## jaypeecee (26 Nov 2019)

dw1305 said:


> You don't actually need added air, you just need to keep the water quality reasonably high, but this is difficult when you feed with yeast.



Hi @dw1305 

When _you_ make a statement like that, Darrel, I sit up and listen. So much so that I had to delve deeper. And I found the following:

https://setac.onlinelibrary.wiley.com/doi/abs/10.1002/etc.5620110311

So, whether it's Daphnia magna or Daphnia pulex, provided that dissolved oxygen is greater than 2.1 mg/l, all should be well. That's a pretty low figure! Of course, it could conceivably drop down that low when feeding with yeast or, indeed, anything else with a high BOD. And that's when aeration must surely help? With reference to your comment that "you just need to keep the water quality reasonably high", would you care to elaborate?

JPC


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## dw1305 (27 Nov 2019)

Hi all, 





jaypeecee said:


> So, whether it's Daphnia magna or Daphnia pulex, provided that dissolved oxygen is greater than 2.1 mg/l, all should be well. That's a pretty low figure!....With reference to your comment that "you just need to keep the water quality reasonably high", would you care to elaborate?


 Yes, agreed these things are all relative. We have figures for the_ Daphnia _species etc. because they are used in water quality bioassay etc. That is actually a reasonably higher level of dissolved oxygen for a species that naturally lives in eutrophic still waters. The situation is slightly different in streams etc., where organisms generally <"have higher oxygen requirements">.  _Daphnia_ are much more sensitive indicator of contamination by <"pyrethroid insecticides"> etc. which is why they are used as a bioindicator.

You can probably visualise situations where you would naturally find _Daphnia_ exposed to low oxygen/high CO2 levels. You could have a warm, stil, night and pond water with a lot of algae present. Where people are using algal ponds ("High Rate Algal Pond") they deliberately add CO2 at night to try and <"reduce zooplankton numbers">. 





jaypeecee said:


> it could conceivably drop down that low when feeding with yeast or, indeed, anything else with a high BOD. And that's when aeration must surely help?


I think if you are feeding yeast you just have to be a lot more rigorous with water changes, cleaning and thinning etc. Adding a snail helps. I don't see any problem with added air as long as you don't have too much water turbulence, and the higher oxygen levels it produces are definitely a bonus.

The <"standard lab. procedure">, (to maximise production), is to feed with a mixture of _Chlorella_ and yeast.

cheers Darrel


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## jaypeecee (27 Nov 2019)

Hi @dw1305 

Many thanks for your reply.

You've answered all my questions.

BTW, I already have a copy of the Reading University SOP. But I chose not to reference it as I thought it may deter people from culturing Daphnia!

JPC


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## idris (27 Feb 2021)

@dw1305 I think I've seen you mention in another thread that breeding daphnia in a water butt needs some hardness.
I've just tested our water butt and it has GH<40 and KH<30 with a pH of 6.3
Is this too low for seeding with daphnia to be viable?


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## dw1305 (27 Feb 2021)

Hi all, 


idris said:


> Is this too low for seeding with daphnia to be viable?


I really don't know, but my suggestion is give it a go and see what happens. 

cheers Darrel


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## idris (27 Feb 2021)

Do the butts need to be open topped? Ours have lids, so I'm struggling to know what the Daphnia would feed on.
And how quickly would you hope a single LFS bag of daphnia would result in a harvestable population in a 200L butt?


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## Karmicnull (30 Mar 2021)

idris said:


> Do the butts need to be open topped? Ours have lids, so I'm struggling to know what the Daphnia would feed on.
> And how quickly would you hope a single LFS bag of daphnia would result in a harvestable population in a 200L butt?



Did you get anywhere with this?  I'm thinking of doing the same thing and had exactly the same questions! Partly for the live food, and partly to give me confidence in my rainwater quality - reading @dw1305's post here I want to understand more

Cheers,
Simon


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## dw1305 (30 Mar 2021)

H all,


Karmicnull said:


> and partly to give me confidence in my rainwater quality - reading @dw1305's post here I want to understand more


Mine have lids on them. The _Daphnia_ feed on any suitable sized items in the water column, so I assume that there are enough rotifers, paramecium etc to keep them going without any algae.

When I say you get a trickle of _Daphnia, _I really mean a trickle, we are talking about a handful or less _Daphnia_ in a 6 pint milk carton. If I want a lot of _Daphnia _I use a bucket of rainwater with a dash of hard tap water and a <"handful of dry grass cuttings">.

cheers Darrel


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## idris (30 Mar 2021)

@Karmicnull I haven't got round to seeding the water butt as I'm focussing on another aquarium issue at the moment.
I was about to say I didn't know what the Daphnia would feed on in the dark, but Darrel just answered that question.  
I might pick up a bag the next time I'm in a LFS.
@dw1305 We have some dried hemp for my kids rats - is that suitable _dry grass_?


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## dw1305 (30 Mar 2021)

Hi all, 


idris said:


> We have some dried hemp for my kids rats - is that suitable _dry grass_?


I would have thought so. 

cheers Darrel


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## Majsa (30 Mar 2021)

I started a daphnia culture outside in an old half wine barrel last summer, and since I wasn't sure they'd survive the winter (which they eventually did), I took a small colony inside for the winter. They lived for about 4 months in a 1,2 liter open top plastic container (basically a cube) at the windowsill, and I put them back in the barrel after the last cold spell. It was a really small colony, I could feed my fish just once a week. I didn't do it the right way I guess, no aeration, and changing all the water once in 7 or 14 days (filtering the daphnia out into another container for in the meanwhile) and washing the container with washing liquid  I gave them spirulina powder or red pepper powder (with chili!) once or twice a week, just a pinch. Every now and then some yeast. Sometimes other organic material such as a leaf or some hay, but not always. The daphnia remained white, almost translucent, compared to the daphnia in the barrel which are a lot bigger and more red. I don't feed those in the barrel.

It has been a matter of trial and error, I've put daphnia in a rain water butt (never saw them back, too soft water?) and tried to culture them in a bowl with a sponge filter (didn't last long, I guess all their food was just filtered away).


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