To be honest I doubt any clip-on reading light could provide a useful amount of light, so the first time I think lack of light would have been the main issue.
Sunlight is good for growing brine shrimp, too much direct sunlight can be an issue as I discovered (algae grows on their exoskeleton and interferes with shedding), but from your description it's hard to tell how much light they are actually getting in this set-up :ermm: .
Definitely remove the marimo ball ASAP! Unlike you may have read elsewhere, it is in no way
compatible with brine shrimp tanks. Brine shrimp prefer water that is of sea water salinity or greater for best growth, this will kill marimo. The clue is in the name, brine=water saltier than seawater, so brineshrimp do best in brine
. All of the studies I have read conclude that seawater salinity (35ppt) is generally the best for Artemia franciscana
, though a higher salinity than this can be beneficial in some ways and may be better for some other species/strains. The instant pet kits (Sea-Monkeys, Aqua Dragons etc.) and hatching kits/instructions for feeding fish will use a lower salinity than seawater, as this gives a better hatch rate, but is much worse for long-term survival and growth. Marimo "moss balls" are actually comprised of a species of algae called Aegagropila linnaei
, this species is sometimes found in brackish conditions (salty, but much less salty than seawater) in the wild, but is far more often found in pure freshwater where it does best. So basically, if the salinity is high enough for your brine shrimp to be growing healthily, then it will be too high for the marimo, which will die and slowly pollute the water, and if the salinity is low enough for the marimo not
to die, then it isn't salty enough for healthy long-term growth of Artemia franciscana
Temperature and feeding regime sound fine, spirulina is a good food too, although I much prefer Aqua Dragon food if you still have any left (Hobby Mikrozell is great too, but expensive). Also I don't think an air pump is essential unless you want to grow very high population densities of shrimp, but if you use one on a low power it can only help.
So essentially, I think you need to make sure the salinity is at least 35ppt and also remove the marimo, hope this helps :) . An aquarium LED or low-wattage florescent light source probably couldn't hurt either, depending on how much sunlight the tank already revives. Algae growth is very important for healthy shrimp IMO.