Okay, sorry it took so long, but I can finally report back on the agar vs. gelatin issue. In summary, I found that:
- You need twice as much gelatin as agar for the same consistency, so gelatin is actually not much (if at all) cheaper.
- Gelatin takes longer to prepare and longer to set.
- Gelatin made a gawdaweful mess in my tank.
The gory details:
In order to be a fair comparison, I decided to make the preparation as similar as possible. To that end, I pre-mixed the gelatin (unflavored Knox) with the other dry ingredients. So at this point, I had two containers with the same amount of vegetable powders, one with agar and one with gelatin (twice as much as the agar).
(Before mixing---agar on left, gelatin on right)
(Gelatin after mixing)
The directions for Knox Blox say to sprinkle the gelatin onto 1/4th of the total water (cool). I put 1/4th of the intended water volume in a bowl and sprinkled in the mix. Because of the volume of veggie powders, there wasn't enough water to make it all wet. Executive decision: I put in another 1/4th of the water and stirred. It made a thick paste.
I then poured the agar mix into my trusty mason jar...
...added the full volume of water (warm) and set it aside.
Next, I boiled water for the gelatin mix, poured it into the bowl with the paste and stirred. The Knox instructions said to stir "until the gelatin was completely dissolved, or about 5 minutes." Well, frappe. The mixture was dark green and I couldn't see the gelatin. So I set my kitchen timer for 5 minutes and started stirring...
...and stirring...
...and stirring...
...are we there yet?
Finally, after five minutes, I poured the gelatin mix into a plastic container, sealed it, and put it in the fridge.
Then I grabbed the agar mix, microwaved it, and poured it into another plastic container (and thought "wow, that was easier").
I originally put the agar mix on the counter to set, but then realized it was too late to do the tank test that night (past bedtime for fishies), so I put it in the fridge with the gelatin mix.
It was actually two days before I had time to do the tank test...
Put them in at the same time. The gelatin wouldn't sink, so I had to put a rock in that container:
(Agar on left, gelatin on right)
The gelatin immediately gave off streams of bubbles (maybe with less stirring, it wouldn't do that?) and started to melt and fall apart.
(You can see the bubbles and bits of gelatin mix streaming up)
After only 25 minutes in the tank, the gelatin looked like this:
In the interest of full disclosure:
- The fish seemed to show a slight preference for the gelatin. I'm not sure if that's because they actually liked it better, or because it was bubbling and breaking apart and being interesting.
- The next day, the agar gel was floating. I've seen this happen once before---the gel started floating after being in the tank for about a day. I don't know why it happens, or why it is only sometimes. If anyone else has seen this, or has a theory about the cause, please share! My best guess is that I occasionally get air pockets in the gel during preparation, which causes it to float once enough of the gel has been eaten away.
:
DOUGHT!
