Trouble growing up brine shrimp

[Hobbit]

I’ve been hatching bbs for a while now and it’s going great! My baby gouramis love them. But I’ve been trying to grow the leftover shrimp up in a separate container, and it’s not working. 😛

I have a 3 liter bowl from our kitchen that I’ve been using as the grow-out container. I don’t have a tds meter or anything to test salinity, but I’ve been using 2 tbsp salt per liter. I have a bubbling air line in there, some crushed oyster shell to help counteract my soft water, and I’ve been feeding them a pinch of spirulina powder once or twice a day. The first time I fed very sparingly, and the second time I fed a bit more. I do have a light on them during the day but I turn it off at night. Our house stays at 70-71. 

I haven’t been scrubbing the bowl out since I figure the same principle applies here as does with our tanks—that beneficial bacteria will grow on the edges of the bowl and on the oyster shell and I want to leave them there. I have replaced the water between attempts though.

Am I thinking of this all wrong? Is there something I’m missing? Do I have too much salt? Too little heat? Too much acid? (Not enough fat? 😉 ) Any tips would be appreciated. 🙂

[Coryndory]

Are they crashing as if it was an ammonia spike due to waste/uneaten food building up?  Do you change the water out every so often or have you tested for ammonia?

[Hobbit]

Sorry, I should have shared parameters from the beginning. 
pH 7
Ammonia 0
Nitrite 0
Nitrate 5

I’ve changed water between attempts. The first attempt probably lasted two weeks and I added shrimp several times. The second attempt lasted 5 days and I only added shrimp once, but on day 4 they were all dead. Those parameters are from today, which is day 5.

[Andy's Fish Den]

The pH of 7 seems off for it being saltwater. Saltwater tanks pH is usually in the 8.0-8.4 range. I'd check the salinity as well, if the pH is off the salinity could be as well.

[gardenman]

There are lots of possibilities. Andy is right, your ph should be higher. A ph of 8.2-8.4 is pretty much the norm for a marine tank. As a rule, smaller volumes of water are harder to control than larger volumes. Three liters is a pretty small volume of water.  When things go bad in a small volume of water they go bad quickly. A larger mass of water (5-10 gallons) might give you more stability. My house stays around 73 degrees, but it varies by several degrees. The temp will drop down to about 67 before the heater comes on and heats it up to about 77. It averages out to 73, but there are swings. In a big volume of water the swings don't matter as much due to the large volume of water. In a smaller volume of water the water can pretty much change with the temp changes. If your bowl finds sunlight at any point of the day the three liters might heat up pretty quickly in the sun. Even the light over it might help to cook the brine shrimp in a small volume of water depending on the type of light it is. 

You might also want to look at alternate feeding options. There are several brine shrimp feeding formulas out there, some of which use human baby food (pureed sweet potatoes and peas) as a base. It's possible your spirulina powder is still too big for them. Once a day is not feeding them often enough from what I've read. They require multiple feedings a day. Many small feedings are typically preferred over one or two larger feedings. If you can't be there all the time, some sort of drip feeder that lets a small volume of food mixed with your salt water drip into the tank slowly might be a good option. Something as simple as a small water bottle (the 16.9 oz size or even smaller) with a hole drilled in the top and a piece of airline tubing glued into the hole and then either an airline valve or a tight knot tied into the tubing to control the flow rate to just a drop every thirty minutes or so, might be effective. (You'll have to be sure you're not restricting things so much that it's preventing the food from getting through though. An aquarium autodoser, like the Jebao ones could be handy for feeding if you have one lying around. They can come on up to 24 times a day so you could schedule in hourly feedings for the brine shrimp. One end of the feed tube would go into what food source you were using and the other into your grow out container. Every hour it could administer a couple of drops of food to your shrimp.

It could also be some impurities in the salt you're using. You never want to use iodized salt. Back when I kept marine fish I would find that if I bought larger volumes of salt mix, that I'd have to really stir them up before use as the salt in boxes or buckets would stratify in shipment. It's not as big an issue if the salt came in bags as they'd get tossed a round a bit more. Coarser grains would be on the top and very fine powders at the bottom. While they blend all of the ingredients at the factory, when they get shipped the vibration from traveling tends to shuffle the lighter stuff to the top and the smaller, heavier stuff to the bottom. If you just take what's on top, you're not getting a true mix unless you stir it up or use the whole volume at once. If you're using a marine mix a few tablespoons at a time, you might be getting an odd mix of ingredients. 

 

[Hobbit]

Thank you both! Unfortunately the 3L bowl is the biggest container i have at the moment. I’ll probably look for some cheap plastic tub or maybe a 5 gallon bucket next time I’m at the store.

I’ll definitely try raising the pH and I’ll also look into the salt issues. I’m using sea salt from the grocery store right now because I’m trying to be cheap, but I do have some other aquarium salt mixes lying around that I can experiment with. And I will give them a good shake. None have iodine thankfully!

If those changes don’t fix the issue, I’ll try to fiddle with heating options next, and then I’ll experiment with food.

You’ve given me quite a list! Thank you!

[L.W. Wetarm]

I’ve started freezing my leftovers in a real cool covered silicone ice cube tray from Amazon. Two cubes are a meal for the entire tank 6 adults and probably  100 babies of 5 different schools. 
 

I have also been curious about raising up some of the BBS. I was thinking along the line of a 5 gallon Lowe’s bucket. 

[Ben_RF]

Something I found that helped me was to begin using a macro algae with the brine shrimp as I raise them to adult.  I personally use chaeto and it has made a world of difference in helping me keep a culture going.