# Made my own media for the first time....



## back2eight (Dec 19, 2005)

..... and it didn't turn out too well. LOL! I've been using Ed's but will run out soon so I decided I better learn how to make some myself. I mixed potato flakes and powdered sugar with some vinegar and water. Put some yeast on top and the coffee filters in and the flies. I also mixed up a regular batch of Ed's just in case the one I tried on my owd didn't turn out. Good thing I did or I'd be in a crisis now. The cultures looked to have the same amount in them. The next few days showed my mix looking very dry so I added some water to it. I was already starting to see maggots in the culture with Ed's media but none in mine. I guess it was too dry. So I add some water. I look at it a little bit later and it had SWELLED up to fill more than half the cup!! Now a few days later I do see a few maggots, but I also see some that look dead. I see a lot of production in my Ed's media cup but it looks like my mix is crashing without producing anything. So, does anyone know what I did wrong? 

I put 50:50 ratio of potato flakes to powdered sugar, and the same with the water and vinegar, half amount of each. Sprinkled the same amount of yeast on the top as I always do, just a few little pieces. 

I need to get this right because I can't keep buying media, its too expensive.


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## hoyta (Jan 18, 2006)

*HEY*

um, you completely left out brewers yeast


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## hoyta (Jan 18, 2006)

*hey*

do a search and find out the correct mixture ratio- i don't know it off the top of my head


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## back2eight (Dec 19, 2005)

> um, you completely left out brewers yeast




No I didn't, I put the yeast in.


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## nburns (May 3, 2005)

I too suggest that you do a search. You made it sound like all you did was use flakes, powdered suger and then sprinkle a little yeast on top. You'll need that brewer's yeast and I believe the flakes to sugar ratio was way off. I use an 8:1 ratio. Good luck!


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## rjmarchisi (Feb 16, 2004)

8 cups potato flakes
1 cup powdered sugar ( superfine will do )
1 cup brewers yeast ( from healthfood store )

mix all dry ingredients together

heat up 1/4 cup water and 1/4 cup vinegar ( I like to nuke it inside the individual mason jars )

add 1/3 cup of the dry mixture

top off with a couple grains of active yeast

let cool down for a couple hours ( don't want to kill the newly added flies )

add coffee filters then flies

Rob


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## Homer (Feb 15, 2004)

My method is a lot like Rob's--similar recipe. The only difference is that I use 1/3 cup dry mix to 3/4 cup of the wet (half water, half vinegar). 1/2 cup of the wet portion makes the mix too dry in my situation--probably different humidity levels in Rob's house than mine, or maybe he adds a little bit of water throughout the life of the culture.

I don't like the smell of vinegar, and am going to experiment with substituting grapefruit juice from concentrate for the vinegar (basically exchanging citric acid for acetic acid) as the mold inhibitor. Has anyone else done this?


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## MikeL (Jun 13, 2006)

Rob/Homer

What kind of vinegar?


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## defaced (May 23, 2005)

Distilled white vinegar. It's like a buck a gallon at the grocery store. I always have to ask the people where it's at because I never remember. Salad dressing isle maybe....?

Homer, I don't see why it wouldn't work provided the mold inhibitor qualities are based soley on pH. Though, I vaguely remember reading when I started in the hobby not to use citrus fruit in media. Keep us posted on what you find out. I'm always playing with my media and it's time for a new batch so I might experiement too.


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## elmoisfive (Dec 31, 2004)

Homer,

A couple of things to think about if one wanted to use citric acid instead of acetic acid in the culture are as follows:

Citric acid, as a tricarboxylic acid is capable of metal chelation which might cause some issues

Citric acid is more acidic than acetic acid, the initial carboxylic acid pKa being roughly 3.2 versus the pKa of acetic acid being approximately 4.8 so it can make the medium more acidic. However given that the second and third carboxylic acids have pKa's of 4.8 and 6.4, citric acid has interesting buffering effects.

On the other hand, citric acid is a pretty darn good preservative so it would definitely work as a mold inhibitor.

Bill


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## Homer (Feb 15, 2004)

defaced said:


> Distilled white vinegar. It's like a buck a gallon at the grocery store. I always have to ask the people where it's at because I never remember. Salad dressing isle maybe....?
> 
> Homer, I don't see why it wouldn't work provided the mold inhibitor qualities are based soley on pH. Though, I vaguely remember reading when I started in the hobby not to use citrus fruit in media. Keep us posted on what you find out. I'm always playing with my media and it's time for a new batch so I might experiement too.


Some people use cider vinegar as well, but it's more expensive, and I think it stinks, too. The whole point is to lower the pH of the media to the level where mold growth is inhibited, but not so low that it interferes with the growth of fly larvae.

Not using citrus fruit in the media is an interesting recommendation. I wonder why that would be? I have heard of some people using apple juice or orange juice as the wet portion and not adding sugar. I have also heard people in Europe say that potato flakes are not suitable for raising fruit flies because they have no nutritional value. :?: Only fruit should be used as the substrate. I think it's probably just a misunderstanding, but I'll be making half of my batch this time using grapefruit juice (and I'll be making twice as many cultures as normal).

I guess we'll find out.


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## Homer (Feb 15, 2004)

elmoisfive said:


> Homer,
> 
> A couple of things to think about if one wanted to use citric acid instead of acetic acid in the culture are as follows:
> 
> ...


Sorry, Bill, your post wasn't showing on my screen when I wrote the last response. I did think about the potential differences in pH between the two acids, and was considering looking for my pH strips to figure out how much water to add to the grapefruit concentrate to get the right concentration of acid to water. However, I am currently remodeling the kitchen, and can't find my pH strips. :? 

Given the fact that I have used a wet mix with as much as 75% vinegar, I know there is plenty of wiggle room here with regard to pH as long as it is low enough to inhibit the mold. I'm not sure what differences might be caused by chelation of any metals, and I hope I don't have too many metals in my media (I use RO water). I guess we will find out one way or the other.

Thanks for the info, Bill!


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## stchupa (Apr 25, 2006)

Homer said:


> I don't like the smell of vinegar, and am going to experiment with substituting grapefruit juice from concentrate for the vinegar (basically exchanging citric acid for acetic acid) as the mold inhibitor. Has anyone else done this?


For years in every culture I make, I add citric fruits pulp/juice. I'll tell you , I wouldn't trade it in for any other mixture with the results I've had with it. But it is tricky to get the ratio correct the first few times, so be persistant with it. Frogs as healthy as any others I've seen.


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## back2eight (Dec 19, 2005)

The media that I messed up on is producing flies. I'm still not sure what made it swell up to almost fill the cup, but I do realize now that I used too much sugar. I will try again.


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## JoshKaptur (Feb 17, 2004)

You most likely did not add enough water when you first mixed it. It expanded to absorb the water you added, but still had room for more. When you added more water, it expanded more.

I use:

8 cups potato flakes
2 cups brewers yeast (this is not the same as the bakers yeast you sprinkle on top)
1 cup regular sugar

Mix with 50:50 water/vinegar until it is wendy's frosty consistency. Wait several minutes as it will harden up and then add water/vinegar mix again to consistency.

Few drops of honey on top supposedly helps the smell. I've always used it, so can't comment if it helps or not.

Josh


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## topaz017 (Jul 30, 2006)

I *think* know the answer .. but I'm going to ask it anyway's.. . If I wanted to just mix up dry goods and store them for later use... and just add water when the times comes... What would I use for a mold inhibitor/and to keep mites out that I could mix in the dry side? I know some already made mixes online have this.. but I cant figure out what they are adding.

Now, I've never made a FF culture yet... I'm getting there... So I could be asking to bake a cake from 2 glasses of water and a rock...

Cant life be easy? I just want to throw in a scoop of dry goods, add some water and yeast to the top and be done.. too simple to work?


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## zBrinks (Jul 16, 2006)

Thats what I do, with a slight difference: I use the 'power mix" with grape juice concentrate, molassas, and a mushed banana boiled together. Fortunately, Ive found I can make alot of it at once, then put it in an ice cube tray and freeze it. Then, when it comes time to make media, I pop 2 cubes in my mason jar, nuke it in the microwave, add the dry ingredients I premixed too (sugar, yeast, instant mashed potatoes, and condensed milk) and add a 50/50 mix of water and vinegar (also premixed in a spare gallon water jug) and let it set for a couple hours before adding flies. I also throw a coffee filter in the culture; this seems to increas productivity ALOT! I spend maybe 30 minutes every couple of months premixing everything, and maybe 5-10 minutes of actual work every week to make 3 cultures. The cultures smell nice, too, and Ive never had any problems with mold afer using this recipe. Each culture produces around 2 times the flies that my cultures using the mashed potato/honey/condensed milk/yeast mix did, and they seem to stay productive for an extra week or two.


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## defaced (May 23, 2005)

topaz017 said:


> I *think* know the answer .. but I'm going to ask it anyway's.. . If I wanted to just mix up dry goods and store them for later use... and just add water when the times comes... What would I use for a mold inhibitor/and to keep mites out that I could mix in the dry side?
> ...
> 
> Cant life be easy? I just want to throw in a scoop of dry goods, add some water and yeast to the top and be done.. too simple to work?


Methylparaben is the mold inhibitor you're looking for, and yes life is that easy - look at the potato flake/sugar/inactive yeast recipie on the first page. 

All of these places have methylparaben, here are links to the pages that have the stuff on it. 

Ed's:
Link

FlyCulture:
Link

Fruit Fly:
Link (You'll have to scroll down till you find it)

---

I've based my media off the power mix for several years. I haven't had great success for a long while now and I'm now starting to think it's because the media was cold (straight from refrigerator) when I added the yeast, hence the yeast didn't do its thing and I didn't get as many flies as I should. Next round of cultures (this weekend) is going to be a bit of an experiement to see if this is the case.

I'm also trying out contractor's paper as the filler. My first cultures from it will be hatching this weekend. I'm hoping it's sturdyness will hold up under culture conditions.


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## back2eight (Dec 19, 2005)

My media that I thought was a flop because it SWELLED up so big, has gone back down somehow and is the best producer I have seen yet! There is something about it that the flies must really like, because every day I am dumping out just about all the flies (even though the frogs are not eating nearly that many because the cup is BLACK with flies) and the next day it is thick with flies again. I am dumping the flies because I don't want it to crash the culture. The next morning there are hundreds more in the cup. 

However, I did find brewers yeast on ebay being sold by the pound so I bought some of it. I will try it in my next batch. This one didn't have any in it.


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